CA1220793A - Concrete additive comprising a multicomponent admixture containing microsilica, its method of manufacture and concrete produced therewith - Google Patents
Concrete additive comprising a multicomponent admixture containing microsilica, its method of manufacture and concrete produced therewithInfo
- Publication number
- CA1220793A CA1220793A CA000431892A CA431892A CA1220793A CA 1220793 A CA1220793 A CA 1220793A CA 000431892 A CA000431892 A CA 000431892A CA 431892 A CA431892 A CA 431892A CA 1220793 A CA1220793 A CA 1220793A
- Authority
- CA
- Canada
- Prior art keywords
- microsilica
- weight
- water
- admixture
- reducing agents
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/04—Waste materials; Refuse
- C04B18/14—Waste materials; Refuse from metallurgical processes
- C04B18/146—Silica fume
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Civil Engineering (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Preparation Of Clay, And Manufacture Of Mixtures Containing Clay Or Cement (AREA)
Abstract
A CONCRETE ADDITIVE COMPRISING A MULTICOMPONENT
ADMIXTURE CONTAINING MICROSILICA, ITS METHOD OF
MANUFACTURE AND CONCRETE PRODUCED THEREWITH
Abstract of the Disclosure A multicomponent admixture is formed with microsilica and stabilized with one or more high-range water-reducing agents or one or more ordinary water-reducing agents alone or in combination. The admixture is of particular advantage when added to fresh concrete or mortar to enhance plasticity, workability and strength as compared to conventional concrete or mortar.
ADMIXTURE CONTAINING MICROSILICA, ITS METHOD OF
MANUFACTURE AND CONCRETE PRODUCED THEREWITH
Abstract of the Disclosure A multicomponent admixture is formed with microsilica and stabilized with one or more high-range water-reducing agents or one or more ordinary water-reducing agents alone or in combination. The admixture is of particular advantage when added to fresh concrete or mortar to enhance plasticity, workability and strength as compared to conventional concrete or mortar.
Description
12;~0793 A CO~C~ ADDITN'E CO~IPRISI~G ~ ~LTICO~O~
TU~ CO~TAI~IN~ ~IICROSILICA, ll`S ~THOD OF
~UrACTu~ D CONCRETE PRODUCED ~HEREWITH
The present invention relates to an additive for concrete which compris~s a multicomponent admixture that contains microsilica and at least one water-reducing agent or at least one high-range water-reducing agent.
Advantageously, the admixture may con~ain one or more er-reducing agents in combination with one or more high-range water-reducino agents along with the microsilic2.
Accelerators and retarders alone or in combination may also be used in the admîxture as optional ingredients.
As ~ne example, the invention is directed to overcome the dra~back associated with degxadation of the air-void system o~ entrained concrete which results from the use of water reducers while at the same time other ~no~n ad~rantages such as workability, strength and formability of concrete which conta;ns waterreducing agents are substantîall~
maintained. In accordance with the present in~ention, the microsilica and at least one water-reduc;ng agent with or without additional optional ingredients are pre-mixed and the resulting admixture is added and miæed into the concrete batch at any desired stage. The premixing is of great advantage as compared to the convell~ional practi~e of nclding each ing~redien~: separately t ~ l:he ~`
~220793 con~rete batch in that the action oE the water-r~d~tc:ing a~ent during pre~nixing tends to uniEormly coat and hom~geneously t disperse the microsilica particles with resulting breakdown cf flocs of material, The flocs of material that tend to form when the ingredients are separately added in conventional practice can be a serious drawback to the desirable uniform strength and durability of the cas~ ¦
c3ncrete. Once flocs are formed in the concrete batch, it requires prolonged mixing to disperse the flocs and over mixing may be deleterious to the workability and formability of the batch.
While the mechanism of premixing is not completely understood, it is believed to provide à synexgiseic effect in the plasticity and workability of the concrete batch along with increased strength over ordinary concrete batches to which the ingredients are separaeely added in conventional practice.
The water-reducing agents and the optional accelerators and retarders of the present invention sre well-known conventional materials currently used in high strength concrete which may have a compressive strength of up to about 6,000 to 12,000 pounds per square inch.
One of the greatest advances in concrete technolog~ in recent decades has been the advent of air enerainment to pro-tect concrete from damage caused by t~e freezing and tha~ing of watex in ehe concrete while it is critically satura~ed an~
TU~ CO~TAI~IN~ ~IICROSILICA, ll`S ~THOD OF
~UrACTu~ D CONCRETE PRODUCED ~HEREWITH
The present invention relates to an additive for concrete which compris~s a multicomponent admixture that contains microsilica and at least one water-reducing agent or at least one high-range water-reducing agent.
Advantageously, the admixture may con~ain one or more er-reducing agents in combination with one or more high-range water-reducino agents along with the microsilic2.
Accelerators and retarders alone or in combination may also be used in the admîxture as optional ingredients.
As ~ne example, the invention is directed to overcome the dra~back associated with degxadation of the air-void system o~ entrained concrete which results from the use of water reducers while at the same time other ~no~n ad~rantages such as workability, strength and formability of concrete which conta;ns waterreducing agents are substantîall~
maintained. In accordance with the present in~ention, the microsilica and at least one water-reduc;ng agent with or without additional optional ingredients are pre-mixed and the resulting admixture is added and miæed into the concrete batch at any desired stage. The premixing is of great advantage as compared to the convell~ional practi~e of nclding each ing~redien~: separately t ~ l:he ~`
~220793 con~rete batch in that the action oE the water-r~d~tc:ing a~ent during pre~nixing tends to uniEormly coat and hom~geneously t disperse the microsilica particles with resulting breakdown cf flocs of material, The flocs of material that tend to form when the ingredients are separately added in conventional practice can be a serious drawback to the desirable uniform strength and durability of the cas~ ¦
c3ncrete. Once flocs are formed in the concrete batch, it requires prolonged mixing to disperse the flocs and over mixing may be deleterious to the workability and formability of the batch.
While the mechanism of premixing is not completely understood, it is believed to provide à synexgiseic effect in the plasticity and workability of the concrete batch along with increased strength over ordinary concrete batches to which the ingredients are separaeely added in conventional practice.
The water-reducing agents and the optional accelerators and retarders of the present invention sre well-known conventional materials currently used in high strength concrete which may have a compressive strength of up to about 6,000 to 12,000 pounds per square inch.
One of the greatest advances in concrete technolog~ in recent decades has been the advent of air enerainment to pro-tect concrete from damage caused by t~e freezing and tha~ing of watex in ehe concrete while it is critically satura~ed an~
-2 lZ20793 in he pr~e-lce o clc-icing chemicals. The ~tse of ~ntr~;ned air is generally x~comm~n~ed itl concrete for alm~t alL
applications. Tes~s have shown that concrete containing about 5 to 7.5%~ ~ 1%, percent by volume air content will withstand up to about l9O0 freeze-thaw cycles as contrasted to a maximum of about 150 cycles of non-air entrained concrete which is identical in all other respects.
See for example3 "Air-Entrained Concrete", Portland Cement As~ociation, Document ISO 45.0~T~ 1967.
There are ~a~ other benefits from the use of air entrained concrete including improved workability, increased resistance ~o de~icers such as calcium chloride, increased sulfate resistance~ and improved water tightness.
One widely used method of makinc air entrained concrete includes the step of adding an air-entraining material during the mixing of the concrete. Experience has indicated that the mixing action is tle most important factor in the production of air-entrained concrete and in this re~ard unif~rm distxibution of entrained aix voîds îs essential to the production of scale~resistance concrete; non-unio~mit~
is always a risk i~ the entrained air is inadequately dispersed during mixing. S~ch factors as the batch size of the`concrete being mixeda the condition of the mixer and the rate of mixing are also impor~ant~ 0ver mixing ma~ even result in a loss of some of the entrained air but the techniques and preferred procedures associated with the mixing phase of air entrained concrete are now rather widely understood, and further amplification is considered unnecessary for those skilled in the art.
A number of air-entraining materials manufactured from a variety of materials are commercially available today such as thermosplastic resins containing phenol aldehyde and ether groups andlthe salts and soaps thereof.
Vinsol* resins are undoubtedly the most widely used air-entraining materials in the United States. Vinsol resin is a thermoplastic resin derived from pine wood and containing phenol aldehyde and ether groups. The sodium soap of Vinsol resin is a particularly effective air-entrain-ing material and only about 0.15% by weight of cement need be used for entraining air in a concrete batch in convention-:
al manner. DAREX AEA* which is a sulfonated hydrocarbon~acid dbrivative of fats and greases sold by Dewey and Almy Chemical Co. is another widely used air-entraining agent.
The air-entrained concrete which results from the use of recognised air-entraining products contains a large number of air bubbles of an extremely small size; average bubble diameter usually ranges from three thousandths to six thousandths of an inch and as many as three hundred to five hundred billion bubbles may be present in a cublc yard '~
~ *Trade Mark ~f air-entrained concrete having an air c~ntent in the range of four to s.ix percent by volum2, and one and one-half inch maximum sized aggregate. The bubbles are n3t interconnected and are well distxibuted throughout the cementlwater phase.
The spacing of th~ air voids is an important factor in ~he freeze-thaw durability of hardened concrete~ and a spacing of less than 0.008 inches, as measured by ASTM C457 standard is considered essential for the attainment of the requisite freeze-thaw resistance.
One of the most sîgnificant developments Ln concrete since air-entrained concrete was developed in the mLd-1930's is the use of so-called water-reducing agents.
Water-reducing agents are chemica~ c~mpounds which, wh~n added to concrete, fluidize the concrete for a period of time so that (1) norm~l workability can be obtained in concrete having much lower water-cement ratios then would normally be`employed or (2~ extremely workable "flowing concrete"
(that is essentially self-leveling without undesirable side effects~ such as segregation, low-durabilîty, low abrasion :resistance, and bleeding~ ca~ be obtained, or ~3) a combination of (1) and (2).
: Water-reducing agents are well-known additives for concxete. The:commercial materials generally available fall into five diferent classes:
:` ~
1. Hydroxy~ed carboxyLic acids and ~heir salts, 2. Modificatior.s and deriv~tives of hydroxyl~ted carboxylic acids and their sal~s,
applications. Tes~s have shown that concrete containing about 5 to 7.5%~ ~ 1%, percent by volume air content will withstand up to about l9O0 freeze-thaw cycles as contrasted to a maximum of about 150 cycles of non-air entrained concrete which is identical in all other respects.
See for example3 "Air-Entrained Concrete", Portland Cement As~ociation, Document ISO 45.0~T~ 1967.
There are ~a~ other benefits from the use of air entrained concrete including improved workability, increased resistance ~o de~icers such as calcium chloride, increased sulfate resistance~ and improved water tightness.
One widely used method of makinc air entrained concrete includes the step of adding an air-entraining material during the mixing of the concrete. Experience has indicated that the mixing action is tle most important factor in the production of air-entrained concrete and in this re~ard unif~rm distxibution of entrained aix voîds îs essential to the production of scale~resistance concrete; non-unio~mit~
is always a risk i~ the entrained air is inadequately dispersed during mixing. S~ch factors as the batch size of the`concrete being mixeda the condition of the mixer and the rate of mixing are also impor~ant~ 0ver mixing ma~ even result in a loss of some of the entrained air but the techniques and preferred procedures associated with the mixing phase of air entrained concrete are now rather widely understood, and further amplification is considered unnecessary for those skilled in the art.
A number of air-entraining materials manufactured from a variety of materials are commercially available today such as thermosplastic resins containing phenol aldehyde and ether groups andlthe salts and soaps thereof.
Vinsol* resins are undoubtedly the most widely used air-entraining materials in the United States. Vinsol resin is a thermoplastic resin derived from pine wood and containing phenol aldehyde and ether groups. The sodium soap of Vinsol resin is a particularly effective air-entrain-ing material and only about 0.15% by weight of cement need be used for entraining air in a concrete batch in convention-:
al manner. DAREX AEA* which is a sulfonated hydrocarbon~acid dbrivative of fats and greases sold by Dewey and Almy Chemical Co. is another widely used air-entraining agent.
The air-entrained concrete which results from the use of recognised air-entraining products contains a large number of air bubbles of an extremely small size; average bubble diameter usually ranges from three thousandths to six thousandths of an inch and as many as three hundred to five hundred billion bubbles may be present in a cublc yard '~
~ *Trade Mark ~f air-entrained concrete having an air c~ntent in the range of four to s.ix percent by volum2, and one and one-half inch maximum sized aggregate. The bubbles are n3t interconnected and are well distxibuted throughout the cementlwater phase.
The spacing of th~ air voids is an important factor in ~he freeze-thaw durability of hardened concrete~ and a spacing of less than 0.008 inches, as measured by ASTM C457 standard is considered essential for the attainment of the requisite freeze-thaw resistance.
One of the most sîgnificant developments Ln concrete since air-entrained concrete was developed in the mLd-1930's is the use of so-called water-reducing agents.
Water-reducing agents are chemica~ c~mpounds which, wh~n added to concrete, fluidize the concrete for a period of time so that (1) norm~l workability can be obtained in concrete having much lower water-cement ratios then would normally be`employed or (2~ extremely workable "flowing concrete"
(that is essentially self-leveling without undesirable side effects~ such as segregation, low-durabilîty, low abrasion :resistance, and bleeding~ ca~ be obtained, or ~3) a combination of (1) and (2).
: Water-reducing agents are well-known additives for concxete. The:commercial materials generally available fall into five diferent classes:
:` ~
1. Hydroxy~ed carboxyLic acids and ~heir salts, 2. Modificatior.s and deriv~tives of hydroxyl~ted carboxylic acids and their sal~s,
3. Inorganic ~aterials such as zinc salts, borates, phosphates and chlorides,
4. Carbohydrates, polysaccharides and sugar acids,
5. Amines and their derivatives and polymeric compounds such as cellulose ethers and silicons,
6. Certain madified lignosul~onic acids.
The terms water-reducing agent and water reducer as used herein are intended to mean one or more of the ingredients in the six foregoing classes of conventional materials alone or i~ comb;n~tion.
The h;gh-range water-reducing agents in widespread commercial use today include: `
1. Lignosulfonic acids and their salts ~nd modi~ications and derivatives thereof ?
2. MelamLne derivàtives, 3. Naphthalene derivatives.
The terms high-xange water reducing agene and high-range water reducer as used herein are intended to mean one or more o the ingredients in the ~oregoing three classes o~ ma~erials alone or in combination.
There are at least twelve widely used high-range water-reducing agen~s, eight o~ which belong ~o the above categories (2) and ~3). The preferred material in ca~egory- (2) ~ ~ `
1220q93 is a cnnventional sulfonated condensate of m~lam;ne and ormaldehyde sold under the brand name o~ Melment and the pre~erred material in cate~ory (3) is a sulfonated condensate of naphthalene and ormaldehyde.
` The high-range water-reducing agents have a much greater plasticizing effect in conventional concrete batches. The best results in workability, forma~ility and strength are achieved by using the high-range water-reducing agents in accordance with the present invention.
Concrete containing high-range water-reducing agents is extensively used in cast-in place concrete work ~here extrem~
flowing characteristics are required such as in areas of high density of reinforcement, pumping, and in complicated form wor~. Amon$ the advantages of the use of high-range water-reducing agents in pre-cast and ready-mix concrete are (a) increased strength at all ages, (b) improved resistance to attack by sulfates, (c) increased bonding to rein~orced steel, (d) Lmproved workability and formability, and (e) reduced permeabilit~ to water penetration.
When a high-range watex-reduci~g agen~ is added to concrete mix, the pla~ticizing ef~ects last for approxima~el~
30-60 minutes, depending on the job conditions. Consequently it should be added àt the job site when used in read~-mixed concrete.
Concrete with one or more high-range water-reducer therein are set out in "Super Plastici~ed Concret~ CI
Journal~ May 1977, pp. N6-Nll inclus~ive, and ~e reerences set out therei.n~
Although concrete which may b~ classified as either `I
air entrained or plasticize~ with water re~ucer has proved eminently feasible for many applications re~uiring only ~he qualities attributable to air entrainm nt or plasticization, dif~iculties have been encountered when the contractor has a~tempted to use both an air-entraining admixture and a high-range water-reducer to plasticize the concrete.
Specifically, it is today universally accepted that th- air-void systèm of hardened air-entrained concrete con- ~
taining a high-range water-reducing agent and neutralized vinsol resin is very poor; that is, the air-void spacing factor is greater than 0.008 inches and there is a potential for losing air from the fresh concrete. As mentioned, the air-void parEmeters, and speci~ically the spacing factor of the air-void system, is a major criteria for predicting the probable performance of concrete to withstand repeated freeze-thaw cycling.
The problem, then, faced by the industry i9 to produce a conerete which possesses the desirable free2e-thaw and allied characteristics of air entrained concrete, together with the excellent workability and increased strengths of water reducer plasticized concrete.
Accordingl~, another object of the invention is to provide`
a water-reducer plasticizing additive for concxete whieh will not reduce but will enhance freeze~thaw resistance~
~2207g3 It has been found that a pre;~ix~d ~dmix~ure o~
miorosilica and ~ne ~r more ~ater-redùcing agents, preferably a high-range water-reducing agent used alone or in combination when added to mortar and concrete increases the density and impermeability of ~hat mortar and concret~ by several orders of magnitude. Indeed, it has been learned that non-air entrained concrete produced with the microsilica admixtur~
of the present invention is virtually imperm~able to the in~ress of freezable water and aggressive fluids~ Concrete -containing the m;crosilica admixture possesses freeze-thaw resistance equal to or better than concrete having proper air entrai~ment and it is of equal or highèr strength.
Thus, deterioration of the air-void system normally experienced with water-reducing agents both ordinaxy and high-range is of no concern since loss of air or increase in bubble spacing is overcome by the beneficial effects of the microsilica admixture with respect to fundamental changes in the pore structure of the binder phase of the concrete.
More specifical~y~ there xesults a moxe uniform dispexsion of the bin~er phase having a significantly finer pore structure.
The microsilica of the present invention is an amorphous silica by-product of the manuacture of ferro-silicon and also silicon metal produced by capturing ~he inely divided particles fro~ stack gases of electric arc furnaces~ Microsilica is a poz~olan, i~e,, it combines ~220793 ;l with lime and moisture at ordinary temperatures to form compounds having cementiti~us properties. The ~ain cons~ituent is silicon dioxide (SiO2) and it is usually presen~ in at least a~out 60% but best results are achieved in the present invention when the SiO2 content is at leàst about 85% by weight.
- An amorphous silica that is eminently sui~able for use in the present invention is obtained as a by-product in the production of silicon metal or ferrosilicon in electric reduction furnaces. In these processes, fairly large quantities of silica are formed as dust which is recovered in filters or other collection apparatus. Such silica can be obtained from Elkem a/s9 Norway.
The analyses and physical data for typical samples o~
silica of this description are given in the following tsbles Dust co~lec~ed in bag filter from production of`Si-M~tal:
Component % by Weigh~
SiO2 : 94 - 98 SiC : 0.2 - 0.7 F 2 3 0.05 - 0.15 TiO2 : 0~01 - 0.02 A1203 : 0.1 - 0~3 MgO : 0.2 - 0~8 : CaO : 0.1 - 0.3 Na20 : 0.3 - 0~5 K20 : 0~2 - 0.6 r~
:~220793 Component V/o by ~eight Mn : O.003 - O.01 Cu : 0.002 - ~.005 Zn : 0.005 - 0.~1 Ni : 0.007 - 0.002 S : 0.1 - 0.3 C : 0.2 - l Q
p : 0.03 - 0.06 Ig~ition loss (1000C) : 0.8 - 1.5 Bulk density, from bunker, g/l : 200 - 300 Bulk density, compacted, g/l 500 - 700 Real density, g/cm3 : 2~20 - 2.25 Specific surface, m2~g : 18 - 22 Prim~r~ particle size, percentage <1 u~ : 9Q
TABL~ 2 Dust col~ected in bag filter from production of 75~ FeSi:
Component % by ~eight SiO2 : 86 - 90 SiC : 0.1 - 0.4 2 3 : 0.3 - 0.9 TiO2 . : 0.02 - 0.06 Al O .: 0.2 - 0.6 MgO : 2.5 - 3~5 CaO : 0.~ - O.S
Na20 : 0~9 - 1~8 X~O : 2.5 3~5 iZ20793 Componen~ CJ, by W~ight Cu Zn ~i _ S : 0.2 - 0.4 C ` : 0.8 - 2.0 P : 0.03 - 0.08 Ignition loss (1000C) : 2.4 - 4.0 Bulk density~ from bun~er, g/l : 200 - 300 Bulk density, compacted, g/l : 500 - 700 Real density, g/cm3 : 2.20 - 2.25 Specific surface, m2/g : 18 - 22 Primary particle size, percentage <l um : 90 . .
Amorphous sil~ca of the above type can be o~tained from other manu~acturers of Si and FeSi, for ~xample, the manu-facture of silicon inYolves the reduction o silica (coarse, silica, e.g. quartz) with carbon. Iron is added if the alloy ferrosilicon is to be manufactured. Part of the product o~
this reduction of silica may be re-oxidized in the ~spour phase (e.g. in air) to orm the fine, particulate silica that is usefu1 herein. -While the dust collected from an electric furnace producing ferrosilicon containing at leas~
75% silicon is preerred, the dust collected from an electric furnace used ~o produce 50% ferrosilicon m~y also bc used in accordance with t~e p~sen~ inv~ntion~
Il~ `- ' '' ' '` ' `' ' ' ~220793 It is pos~ib~e to obtain the amorph~us silica not as a by-produc~ but as the major product, by appropriately adjusting the reaction conditions. Amorphous silica ~f this type may also be produced synthetically without reduction and re-oxidation.
The amorphous sili^a used in the present invention is composed substantially of sub-micron, spherical particles.
The spherical shape together with its fineness pozzolanic artivity ~akes it surpirsingly useful in accordance with the present invention.
For example, the amorphous silica particles may consist of at least 60 to 90~ by weight of SiO2, will have a real density of 2.20-2.25 g/cm3 and will have a specific surface area of 18-22 m2/g, the particles being substantially spherical, and wherein at least 90% by weight of the primary particles have a pàrticle size of less than 1 micxon. Of course, variation of these values is readily possible. For example, the silica may have a lower SiO2 content. Moreover, the particle size distribution can be a~justed; thus, it is possible to remove coarser particles, by classification.
The amorphous silica may be dark gray in color owing to a`content of carbon. However, this carbon can be burnt off, e.g. at temperatures of about 400C. It is also possible , ~- to modify the silicon and ferrosilicon manufacturing processes as to obtain the silica in a comparatively white ~oxm whic~
is otherwise ~irtual~y identical with the gray silica no~mall~
12207g3 produced. Essentially, th~ process modiEication consists of reducing the amount o~ coal in, or eliminating coal from, the chaxge. The other consequ~nce of this modification is a change in the proportion o~ silica produced t~ the amount o silicon or ferrosilicon; in other words, the ratio of silica to silicon or ferrosilicon is higher in the modified process.`
The terms microsilica as used herein is intended to ~ean the particulate amorphous silica obtained by a process in which silica is reduced and the reduction product is oxidized in the vapour phase in air. The said term micro-silica als~ includes the sampe type of amorphous silica produced synthetically without reduction and re-oxidation.
M~st conveniently, the microsilica of the present inven~ion is o~tained from the of-gas of silicon metal or ferrosilicon produced in electric reduction furnaces.
The admixture of the present invention comprises from about 3070 to ~bout 98% by weight of microsilica and rom about 2% to about 50% of one or more water-reducing agan~s based on the weight of the microsilica in the admixture.
One or more high-range water-reducing agents may be used either alone or in combination with one or more ordinar~
water-reducing agents. These are the essential ingredients in the microsilica admixture in which the selected high-range or ordinary water-reducing agent is uniformly and homogeneously dispexsed in the microsilica.
122~'793 The ingredients ~ay be mi~d in any ~onventional mixing apparatus and in one example 50 ?ounds of mierosilica and 5 pounds of ~Ieltn~nt high-range water-reducing agent are fed to a rotary dry batch drum type blender to uniformly and homogeneously disperse the particulate ingredients in intim~te contact in the admixture in accordance with the present invention. Best results are achieved by mixing the essential ingredients in aqueous slurry to insure intimate contact between the ingredients and a uniform homogeneous dispersion.
The aqueous slurry admixture may comprise from about 10% to about 80a/o by weight of microsilica and pxeferably from about 40% ~o about 60% by weight of microsilica and from about 0.5% to about 40% by weight (dry weight) of one or more high-range or ordinary water-reducing agent alone or in combination and preferably from about 1.0% to abo~
20% by weight of said high-range or ordinary water-reducing agent àlone or in combination therein, ~he balance being wa~er. In one exa~ple 45 pounds of microsilica, 3 pounds of commercial grade of sulonated condensate o napht~alen~
formaldehyde (high-rsnge water-reducing agent~ and 3 pounds of a commercial grade of cellulose ether (water-reducing agen~) are uniorm1y and homogeneously dispersed in S.5 gallons of water pre~erably in a Banbury mixer~ The pH of ~he aqueous slurry may be adjusted with conventional mineral acid or alkali to between about 3.0 to about 7.5 and preexably -lS``
r~
~220793 bet~2en about 5.0 to about 6.0 in order to obtain a slurry of prop~x consistency for transportation and mixing int~
the concrete batch. In addition or instead of adjusting ~he pH of the slurry one may use dispersing agents such as phosphates, citric acid, polyacrylates or glycerine in order to obtain the desired slurry consistency. Water is the most economical liquid to use in forming the admixture slusry of the present invention but, if desired, an organic liquid may be employed provided that it is compatible with the concrete and i~ not otherwise deleterious.
Relative viscosity of aqueous slurry admixtures of the present invention were recorded using a Haake viscometer ueilizing~a E-30 sensor and the standard procedure described by~the manufacturer and compared to a blank aqueous slurry containing the same amoùnt of microsilioa withoue any wster-reducing agent. In each sample the slurry contained 65Z by weight of microsilica for comparison. The following d~ata was recorded in these tests:
` ~ INVERSE
Speed of1 HR. 7 Days 28 Days SensorMeasured Measured Measured Rotation Torque Torque Torque `~ 32 53 150 150 " 8 60 150 150 ` 4 64 150 150 2 69 lS0 150 1 78 150 lS0 Yield Point 49 150 150 ~16~
lZ20793 INVERSE
Speed of1 HR, 7 Days 28 Days Sensor~leasured ~leasured Measured Sample Rotation Torque Torque Torque Sample A
Ligno Sulfonate 32 4 8 11 2.5% by Weight (80rresperse*NA) 16 4 11 16 8 5 11 ~7 4 6 12 ` 18 Yield Point 2 3.5 15~0 :
Sample B
Sulfonated 32 18 17 26 condensate of naphthalene and 16 20 21 - 27 formaldehyde 2.5% by Weight 8 25 23 26 (might~5 ` - 27 24 25 Yield Point 28 28 43 Sa~ple C
Sulfona~ed 32 21 57 55 condensate of melamine and 16 3~ 63 61 formaldehyde 2.5% by Weight 8 33 68 64 CRescon~Hp) 36 74 69 49 9~ 8 ~ield Point 32 63 7 ~A~ 17~
p.s shown in the f~regt~ing data, microsilica will tend to :Eorm a thixotropic mixture in water which requently results in a gelling o~ the aqueous slurry. When the slurry gels it is not satisfactory since as a practical matter it is extremely difficult to pump from storage.
It was quite surprising and unexpected to find tha~ the high-range water-reducing agent of Samples B and C above and ordinary water-reducing agen~ of Sample A above were ef~_c~ive to reduce the tendency for the aqueous slurry to gel as often is experienced with microsilic~ alone in aqueous slurry.
It is believed that during mixing the high-range and ordinary water-reducing agents tend to coat the surace of the microsilica particles and thereby effec~iveIy reduced the tendency for the slurry to gel. Experience has shown that when the yield point in the above table is in the neighborhood of about 25 the aqueous slurry is excellent for use in`accordance with the present invention and the aqueous slurry is satisfactory up eo a yield point of about 75. When the yield point of the slurry is abo~e about 100 ie becomes difficult to pump and ehe slurry is noe deemed saeisfactor~ for use in accordance with ~he present inveneion.
In accordance with the present invention, aqueous slurrys of microsilica axe seabilized and the tendency to gel rl~y be m;~eri~lly reduc~d or elimin~ted by dispersing ~ron~ about 0.1% to about 10.0% and preferably from about 2.0% to 5.0% of high-range or ordinary water-reducing agent by weight (dry basis) based on the weight of microsilica in the aqueous slurry. In general, the amount of microsilica in the aqueous slurry will comprise from about as little as 5% and up to about ~0% by weight. One or more high-range or ordinary water-reducing agents m~y be used alone or in co~ination in order to stabilize the microsilica aqueous slurry admixture. WhPn the aqueous slurry admixture is to be used as an additive or concrete or mortar the amount of high-range or ordinary water-reducing agent may e~ceed ~0% by weight and as specified hereinabove may constitut`e from about 0.5CfO to about 40% by weight of the aqueous slurry admixture.
The amount of admixture of the present invention to be added to conventional fresh concre~e mixtures or mortar will vary depending upon the application at hand. The amount of admixture to be added is based on the weiOht of cem~nt in the concrete or mortar batch.
In general, a suficient quantit~ o the a~mix~ure o~ the present invention is added and mi~ed into a fresh concrete or mortar batch to provide therein rom about 2~0% to about 100% and preferably from about 2% to 25~
by weight of dry microsilica based on the ~eight of cemPnt ;n the concrete batch and from ~bout 0.1% to 2bout 5% by weight of high-range or ordinary water-reducing agent alone or in combination based on the weight of cem~n~ in the concrete or mortar batch.
In accordance with standard industry practice, the optimum amount of the ingredients in the admixture an~ the amount of admi~ture within the specified range to be added ~o the concrete with the job materials at hand is de~mined by tests that simulate the ambient conditions and construction procedures to be encountered on the construction job. Conventional tests are employed to indicate the effect of the admixture on the concrete inso~ar as pertinent to the job with respect to air content of the concrete, consistency, bleeding of water and possible loss of air from fresh concrete~ rate of hardening, compressive and fle~ural strength, resistance to freezing and thawing, shrinkage on drying and permissible chloride con~ent.
The conventional addition of high-rangP and ordinary wate,-reducing agents frequently cause the concrete batch to bleed excessively and segregate as indicated by a thin watery paste wh~ch fails to hold the coarse aggregate particles in suspension. It is also kno~ that most high-range and ordinary water-reducing agents tend to e~ec~
plasticization by reducing the sur~ace tension of the water component of the concrete mi~ture. This may resul~
~:Z20793 in s~p~rati~n oE coarse aggreg~te particles ~nd result in low Ereeze-tha~ resis~ance, 109s oE pumpability, poor abrasion resistance, difficulty in the finishing operation and p~r surface texture in form work.
The addition of micro~ilica ~rom the admixture of the present invention with i~s high de~ree of fineness increases the surface area of the solids per unit of water volume, thus `-achieving better separation and suspension of coarse aggregate particles and results in increased plasticity and wo~ka~ility through change in particle interference. Since the mix~ure of cement, water and admixture of the invention contains more solids per unit volume, the paste is less wa~ery and less inclined to separate. Bleeding is thereby reduced by the microsilica by holding the water in paste. This results in a homogeneous, highly-wor~able, pumpable mixture with reduced bleeding characteristics.
Compressive strength achieved by concrete containing the admixture of the present i~vention is generally higher than one ~ould expect from the addition of increments of strength gained through the addition of each ingredient separately. The reason for this is not fully understoca bu~ it is believed that the high-range or ordinary water-reducing agent gives better distribution throughou~ the concrete mass to the microsilica particles and that certain synergistic effects e~ist between the admixture inoredients.
_ . ~
~220793 The a~ ture o.E the present inv~nti~n ;s use~ t~
adv~nta~e in conventional fresh concrete mixes and is mixed into the concrete mass using ~he conventional techniques now employed for mixing concre~e batches.
For example, an aqueous slurry admixture containing 45 pounds of microsilica, 8 pounds of dry Lomar ~ (high-rangP
water-reducing agent, sulfonated condensate of naphthalene and ~ormaldehydP) and 5.5 gallons of water may be added an~ mixed into a conventional fresh concrete batch containin~
450 pounds of Portland cement Type I without any other additives. The resulting concrete mixture at a water to cemRnt ratio of 0.35 by weight has good workability, consistency and no segregation in the fresh state. In the hardened stat(è, the 28 day compressive strength is typically unexpectedly high and of the order of 12jO00 p.s.i. and the freeze-thaw resistance is surprisingly high even in the absence o air entrainment. The concrete mixture contains 10% microsilica (dry) and about 1.8% of Lomar D
(dry) based on the weight of cement in the concrete mix.
The decreased permeability of the resulting mixture increases the resistànce to ingress o~ water an~
aggressive chemicals with a resulting improvement in freeze-thaw characteristics compared to concrete or mortar mixtures that do not include said microsilica aqueous slurry admixture.
~
The admixture o the pr~sent invention is premi~ed in optimum proporti~ns as determ~ned by standard industry tests to provide a single dispensing system as compared to con~enti~nal practice where three t~ four dispensing systems are required at the job site. Dispensing of all additives may be carried out simultaneously with the admixture of the present invention in ~hich the ingredients are in uniform and homogeneous dispersion as compared to the c~ventional practice ~f adding the separate ingredients sequentially in order to avoid flocculation. The admixture of the invention saves on truck loading time and reduces error in that only one batch ~ddition is required rather than three or four. Storage facilities are xeduced and quality control is increased by having a single manu~acturer supply all àdditives ;n the single admixture of the present invention which eliminates the problem of storage tank contamination. Another advantage of the aqueous slurry ~orm of admixture of the present invention is that it eliminates fine particle dust at the Job site. Although on smaller jobs, the dxy particulate admixture may be packaged in 80 to 100 pound bags and delivered to the job site.
The ability of the admixt~re of the present invention to impart inc~eased sulfate resistance and inoreased resistance to alkali-silica reaction in concrete containing it, will be realized ~rom the beneicial efects of micro-silica added to th~ concrete mi~ture.
~23 i2:~0793 Since the admixture of tll~ present inv~ntion may be used in conditions which may length~n setting time to an objectionable ~egree, accelerating ingredients may be added to the admixture to provide optimum setting and early strength gain characteristics. Further, it may be desirable to retard the setting tLme of the fresh concrete 8S for example in a bridge deck so that hardening ta~es place after the placing and finishing operations are co-~3leted.
The admixture of the present invention is tail~r m~de with optimum ingredients and amounts of ingredients for the concrete to be used in the construction job at hand.
Any of the known additives conventionally used in batching concrete or mortar may be incorp~rated into the admixture of the present invention.
Accel~rators such as the kn~ calcium chloride, calcium nitrate and calcium formate may be incorporated into the admigture with the essential ingredients in amounts that are currently used in the industry as dete~mined by s~andard test ~or optimum quantity ~or the application at hand. One or more accelerators will comprise from about 5% to about 20~ by weight based on the weight of microsilica in the admixture.
Retarders such as sugar in the form of glucosè or sucrose conventionally used in concxete or mortar batches ~2~0793 may also be incorporated in the admixture in opti~um amounts as determined by standard testing. One or more retarders may be present in an am~unt o~ from about 5~/O
~o about 20% by weight based on the weight ~E microsilica in the admixture.
If desired, air entraining agents such as Vinsol resin or Darex which is a sulfonated fatty acid derived from fats and greases may be incorporated into the 2 m;xture of the present invention in those particular 2?plications where a given level of entrained air may be a desirable characteristic. One or more air entraining agents may be pxesent in an amount of from about 0.5yo to about 2% by weight based on the weight of microsilica.
Any one or more additives alone or in combination with other additives may be incorporated with the essential ingredients in the admixture of the present invention. Compatibility and consistency of the admixture is determined by routine standard testing as well as the final effect on the particular concrete or mortar batch to be used in the construc~ion job at hand.
The admixture of the present invention may con~ain various proportions of the selected ingredients but in order to realize the beneit o the present in~ention, the amount of admixture mixed into a conventional fres~
TRA~ ~RQ~
1220'793 concrete ba~ch ~ill be sufficient to provide from ~bout `2.0% to abou~ 100% by weight of m~crosilica based on the weight of cement and from about 0.1% to about 5% by weight o one ~r more of the high-range or ordinary water-reducing agents alone or in combination based on the weight of cement.
Water or an organic liquid compatible with fresh concrete is preferably added to the admixture in an amount su~ficient to provide a slurry with the essential ingredients ~niformly ~n~ homogeneously dispersed therein. Accelerators, retarders, air entraining agents and any other conventional additives a re mixed with the essential ingredients of the admixture of the present invention in an amount sufficient to provide the desired concentration in the fresh concrete batch. In all cases the optimum amount of ingredients present in the admixture of the present invention is determined by standard conventional testing under the simulated ambient conditions for the job m~terials at hand and construction procedures to be used.
It will be understood that it is intended to cover all changes and modifications of the pxeerred embodiment of the invention herein chosen or the purpose of illustration which do not constitute a departure rom the spirit and scope of the invention.
The terms water-reducing agent and water reducer as used herein are intended to mean one or more of the ingredients in the six foregoing classes of conventional materials alone or i~ comb;n~tion.
The h;gh-range water-reducing agents in widespread commercial use today include: `
1. Lignosulfonic acids and their salts ~nd modi~ications and derivatives thereof ?
2. MelamLne derivàtives, 3. Naphthalene derivatives.
The terms high-xange water reducing agene and high-range water reducer as used herein are intended to mean one or more o the ingredients in the ~oregoing three classes o~ ma~erials alone or in combination.
There are at least twelve widely used high-range water-reducing agen~s, eight o~ which belong ~o the above categories (2) and ~3). The preferred material in ca~egory- (2) ~ ~ `
1220q93 is a cnnventional sulfonated condensate of m~lam;ne and ormaldehyde sold under the brand name o~ Melment and the pre~erred material in cate~ory (3) is a sulfonated condensate of naphthalene and ormaldehyde.
` The high-range water-reducing agents have a much greater plasticizing effect in conventional concrete batches. The best results in workability, forma~ility and strength are achieved by using the high-range water-reducing agents in accordance with the present invention.
Concrete containing high-range water-reducing agents is extensively used in cast-in place concrete work ~here extrem~
flowing characteristics are required such as in areas of high density of reinforcement, pumping, and in complicated form wor~. Amon$ the advantages of the use of high-range water-reducing agents in pre-cast and ready-mix concrete are (a) increased strength at all ages, (b) improved resistance to attack by sulfates, (c) increased bonding to rein~orced steel, (d) Lmproved workability and formability, and (e) reduced permeabilit~ to water penetration.
When a high-range watex-reduci~g agen~ is added to concrete mix, the pla~ticizing ef~ects last for approxima~el~
30-60 minutes, depending on the job conditions. Consequently it should be added àt the job site when used in read~-mixed concrete.
Concrete with one or more high-range water-reducer therein are set out in "Super Plastici~ed Concret~ CI
Journal~ May 1977, pp. N6-Nll inclus~ive, and ~e reerences set out therei.n~
Although concrete which may b~ classified as either `I
air entrained or plasticize~ with water re~ucer has proved eminently feasible for many applications re~uiring only ~he qualities attributable to air entrainm nt or plasticization, dif~iculties have been encountered when the contractor has a~tempted to use both an air-entraining admixture and a high-range water-reducer to plasticize the concrete.
Specifically, it is today universally accepted that th- air-void systèm of hardened air-entrained concrete con- ~
taining a high-range water-reducing agent and neutralized vinsol resin is very poor; that is, the air-void spacing factor is greater than 0.008 inches and there is a potential for losing air from the fresh concrete. As mentioned, the air-void parEmeters, and speci~ically the spacing factor of the air-void system, is a major criteria for predicting the probable performance of concrete to withstand repeated freeze-thaw cycling.
The problem, then, faced by the industry i9 to produce a conerete which possesses the desirable free2e-thaw and allied characteristics of air entrained concrete, together with the excellent workability and increased strengths of water reducer plasticized concrete.
Accordingl~, another object of the invention is to provide`
a water-reducer plasticizing additive for concxete whieh will not reduce but will enhance freeze~thaw resistance~
~2207g3 It has been found that a pre;~ix~d ~dmix~ure o~
miorosilica and ~ne ~r more ~ater-redùcing agents, preferably a high-range water-reducing agent used alone or in combination when added to mortar and concrete increases the density and impermeability of ~hat mortar and concret~ by several orders of magnitude. Indeed, it has been learned that non-air entrained concrete produced with the microsilica admixtur~
of the present invention is virtually imperm~able to the in~ress of freezable water and aggressive fluids~ Concrete -containing the m;crosilica admixture possesses freeze-thaw resistance equal to or better than concrete having proper air entrai~ment and it is of equal or highèr strength.
Thus, deterioration of the air-void system normally experienced with water-reducing agents both ordinaxy and high-range is of no concern since loss of air or increase in bubble spacing is overcome by the beneficial effects of the microsilica admixture with respect to fundamental changes in the pore structure of the binder phase of the concrete.
More specifical~y~ there xesults a moxe uniform dispexsion of the bin~er phase having a significantly finer pore structure.
The microsilica of the present invention is an amorphous silica by-product of the manuacture of ferro-silicon and also silicon metal produced by capturing ~he inely divided particles fro~ stack gases of electric arc furnaces~ Microsilica is a poz~olan, i~e,, it combines ~220793 ;l with lime and moisture at ordinary temperatures to form compounds having cementiti~us properties. The ~ain cons~ituent is silicon dioxide (SiO2) and it is usually presen~ in at least a~out 60% but best results are achieved in the present invention when the SiO2 content is at leàst about 85% by weight.
- An amorphous silica that is eminently sui~able for use in the present invention is obtained as a by-product in the production of silicon metal or ferrosilicon in electric reduction furnaces. In these processes, fairly large quantities of silica are formed as dust which is recovered in filters or other collection apparatus. Such silica can be obtained from Elkem a/s9 Norway.
The analyses and physical data for typical samples o~
silica of this description are given in the following tsbles Dust co~lec~ed in bag filter from production of`Si-M~tal:
Component % by Weigh~
SiO2 : 94 - 98 SiC : 0.2 - 0.7 F 2 3 0.05 - 0.15 TiO2 : 0~01 - 0.02 A1203 : 0.1 - 0~3 MgO : 0.2 - 0~8 : CaO : 0.1 - 0.3 Na20 : 0.3 - 0~5 K20 : 0~2 - 0.6 r~
:~220793 Component V/o by ~eight Mn : O.003 - O.01 Cu : 0.002 - ~.005 Zn : 0.005 - 0.~1 Ni : 0.007 - 0.002 S : 0.1 - 0.3 C : 0.2 - l Q
p : 0.03 - 0.06 Ig~ition loss (1000C) : 0.8 - 1.5 Bulk density, from bunker, g/l : 200 - 300 Bulk density, compacted, g/l 500 - 700 Real density, g/cm3 : 2~20 - 2.25 Specific surface, m2~g : 18 - 22 Prim~r~ particle size, percentage <1 u~ : 9Q
TABL~ 2 Dust col~ected in bag filter from production of 75~ FeSi:
Component % by ~eight SiO2 : 86 - 90 SiC : 0.1 - 0.4 2 3 : 0.3 - 0.9 TiO2 . : 0.02 - 0.06 Al O .: 0.2 - 0.6 MgO : 2.5 - 3~5 CaO : 0.~ - O.S
Na20 : 0~9 - 1~8 X~O : 2.5 3~5 iZ20793 Componen~ CJ, by W~ight Cu Zn ~i _ S : 0.2 - 0.4 C ` : 0.8 - 2.0 P : 0.03 - 0.08 Ignition loss (1000C) : 2.4 - 4.0 Bulk density~ from bun~er, g/l : 200 - 300 Bulk density, compacted, g/l : 500 - 700 Real density, g/cm3 : 2.20 - 2.25 Specific surface, m2/g : 18 - 22 Primary particle size, percentage <l um : 90 . .
Amorphous sil~ca of the above type can be o~tained from other manu~acturers of Si and FeSi, for ~xample, the manu-facture of silicon inYolves the reduction o silica (coarse, silica, e.g. quartz) with carbon. Iron is added if the alloy ferrosilicon is to be manufactured. Part of the product o~
this reduction of silica may be re-oxidized in the ~spour phase (e.g. in air) to orm the fine, particulate silica that is usefu1 herein. -While the dust collected from an electric furnace producing ferrosilicon containing at leas~
75% silicon is preerred, the dust collected from an electric furnace used ~o produce 50% ferrosilicon m~y also bc used in accordance with t~e p~sen~ inv~ntion~
Il~ `- ' '' ' '` ' `' ' ' ~220793 It is pos~ib~e to obtain the amorph~us silica not as a by-produc~ but as the major product, by appropriately adjusting the reaction conditions. Amorphous silica ~f this type may also be produced synthetically without reduction and re-oxidation.
The amorphous sili^a used in the present invention is composed substantially of sub-micron, spherical particles.
The spherical shape together with its fineness pozzolanic artivity ~akes it surpirsingly useful in accordance with the present invention.
For example, the amorphous silica particles may consist of at least 60 to 90~ by weight of SiO2, will have a real density of 2.20-2.25 g/cm3 and will have a specific surface area of 18-22 m2/g, the particles being substantially spherical, and wherein at least 90% by weight of the primary particles have a pàrticle size of less than 1 micxon. Of course, variation of these values is readily possible. For example, the silica may have a lower SiO2 content. Moreover, the particle size distribution can be a~justed; thus, it is possible to remove coarser particles, by classification.
The amorphous silica may be dark gray in color owing to a`content of carbon. However, this carbon can be burnt off, e.g. at temperatures of about 400C. It is also possible , ~- to modify the silicon and ferrosilicon manufacturing processes as to obtain the silica in a comparatively white ~oxm whic~
is otherwise ~irtual~y identical with the gray silica no~mall~
12207g3 produced. Essentially, th~ process modiEication consists of reducing the amount o~ coal in, or eliminating coal from, the chaxge. The other consequ~nce of this modification is a change in the proportion o~ silica produced t~ the amount o silicon or ferrosilicon; in other words, the ratio of silica to silicon or ferrosilicon is higher in the modified process.`
The terms microsilica as used herein is intended to ~ean the particulate amorphous silica obtained by a process in which silica is reduced and the reduction product is oxidized in the vapour phase in air. The said term micro-silica als~ includes the sampe type of amorphous silica produced synthetically without reduction and re-oxidation.
M~st conveniently, the microsilica of the present inven~ion is o~tained from the of-gas of silicon metal or ferrosilicon produced in electric reduction furnaces.
The admixture of the present invention comprises from about 3070 to ~bout 98% by weight of microsilica and rom about 2% to about 50% of one or more water-reducing agan~s based on the weight of the microsilica in the admixture.
One or more high-range water-reducing agents may be used either alone or in combination with one or more ordinar~
water-reducing agents. These are the essential ingredients in the microsilica admixture in which the selected high-range or ordinary water-reducing agent is uniformly and homogeneously dispexsed in the microsilica.
122~'793 The ingredients ~ay be mi~d in any ~onventional mixing apparatus and in one example 50 ?ounds of mierosilica and 5 pounds of ~Ieltn~nt high-range water-reducing agent are fed to a rotary dry batch drum type blender to uniformly and homogeneously disperse the particulate ingredients in intim~te contact in the admixture in accordance with the present invention. Best results are achieved by mixing the essential ingredients in aqueous slurry to insure intimate contact between the ingredients and a uniform homogeneous dispersion.
The aqueous slurry admixture may comprise from about 10% to about 80a/o by weight of microsilica and pxeferably from about 40% ~o about 60% by weight of microsilica and from about 0.5% to about 40% by weight (dry weight) of one or more high-range or ordinary water-reducing agent alone or in combination and preferably from about 1.0% to abo~
20% by weight of said high-range or ordinary water-reducing agent àlone or in combination therein, ~he balance being wa~er. In one exa~ple 45 pounds of microsilica, 3 pounds of commercial grade of sulonated condensate o napht~alen~
formaldehyde (high-rsnge water-reducing agent~ and 3 pounds of a commercial grade of cellulose ether (water-reducing agen~) are uniorm1y and homogeneously dispersed in S.5 gallons of water pre~erably in a Banbury mixer~ The pH of ~he aqueous slurry may be adjusted with conventional mineral acid or alkali to between about 3.0 to about 7.5 and preexably -lS``
r~
~220793 bet~2en about 5.0 to about 6.0 in order to obtain a slurry of prop~x consistency for transportation and mixing int~
the concrete batch. In addition or instead of adjusting ~he pH of the slurry one may use dispersing agents such as phosphates, citric acid, polyacrylates or glycerine in order to obtain the desired slurry consistency. Water is the most economical liquid to use in forming the admixture slusry of the present invention but, if desired, an organic liquid may be employed provided that it is compatible with the concrete and i~ not otherwise deleterious.
Relative viscosity of aqueous slurry admixtures of the present invention were recorded using a Haake viscometer ueilizing~a E-30 sensor and the standard procedure described by~the manufacturer and compared to a blank aqueous slurry containing the same amoùnt of microsilioa withoue any wster-reducing agent. In each sample the slurry contained 65Z by weight of microsilica for comparison. The following d~ata was recorded in these tests:
` ~ INVERSE
Speed of1 HR. 7 Days 28 Days SensorMeasured Measured Measured Rotation Torque Torque Torque `~ 32 53 150 150 " 8 60 150 150 ` 4 64 150 150 2 69 lS0 150 1 78 150 lS0 Yield Point 49 150 150 ~16~
lZ20793 INVERSE
Speed of1 HR, 7 Days 28 Days Sensor~leasured ~leasured Measured Sample Rotation Torque Torque Torque Sample A
Ligno Sulfonate 32 4 8 11 2.5% by Weight (80rresperse*NA) 16 4 11 16 8 5 11 ~7 4 6 12 ` 18 Yield Point 2 3.5 15~0 :
Sample B
Sulfonated 32 18 17 26 condensate of naphthalene and 16 20 21 - 27 formaldehyde 2.5% by Weight 8 25 23 26 (might~5 ` - 27 24 25 Yield Point 28 28 43 Sa~ple C
Sulfona~ed 32 21 57 55 condensate of melamine and 16 3~ 63 61 formaldehyde 2.5% by Weight 8 33 68 64 CRescon~Hp) 36 74 69 49 9~ 8 ~ield Point 32 63 7 ~A~ 17~
p.s shown in the f~regt~ing data, microsilica will tend to :Eorm a thixotropic mixture in water which requently results in a gelling o~ the aqueous slurry. When the slurry gels it is not satisfactory since as a practical matter it is extremely difficult to pump from storage.
It was quite surprising and unexpected to find tha~ the high-range water-reducing agent of Samples B and C above and ordinary water-reducing agen~ of Sample A above were ef~_c~ive to reduce the tendency for the aqueous slurry to gel as often is experienced with microsilic~ alone in aqueous slurry.
It is believed that during mixing the high-range and ordinary water-reducing agents tend to coat the surace of the microsilica particles and thereby effec~iveIy reduced the tendency for the slurry to gel. Experience has shown that when the yield point in the above table is in the neighborhood of about 25 the aqueous slurry is excellent for use in`accordance with the present invention and the aqueous slurry is satisfactory up eo a yield point of about 75. When the yield point of the slurry is abo~e about 100 ie becomes difficult to pump and ehe slurry is noe deemed saeisfactor~ for use in accordance with ~he present inveneion.
In accordance with the present invention, aqueous slurrys of microsilica axe seabilized and the tendency to gel rl~y be m;~eri~lly reduc~d or elimin~ted by dispersing ~ron~ about 0.1% to about 10.0% and preferably from about 2.0% to 5.0% of high-range or ordinary water-reducing agent by weight (dry basis) based on the weight of microsilica in the aqueous slurry. In general, the amount of microsilica in the aqueous slurry will comprise from about as little as 5% and up to about ~0% by weight. One or more high-range or ordinary water-reducing agents m~y be used alone or in co~ination in order to stabilize the microsilica aqueous slurry admixture. WhPn the aqueous slurry admixture is to be used as an additive or concrete or mortar the amount of high-range or ordinary water-reducing agent may e~ceed ~0% by weight and as specified hereinabove may constitut`e from about 0.5CfO to about 40% by weight of the aqueous slurry admixture.
The amount of admixture of the present invention to be added to conventional fresh concre~e mixtures or mortar will vary depending upon the application at hand. The amount of admixture to be added is based on the weiOht of cem~nt in the concrete or mortar batch.
In general, a suficient quantit~ o the a~mix~ure o~ the present invention is added and mi~ed into a fresh concrete or mortar batch to provide therein rom about 2~0% to about 100% and preferably from about 2% to 25~
by weight of dry microsilica based on the ~eight of cemPnt ;n the concrete batch and from ~bout 0.1% to 2bout 5% by weight of high-range or ordinary water-reducing agent alone or in combination based on the weight of cem~n~ in the concrete or mortar batch.
In accordance with standard industry practice, the optimum amount of the ingredients in the admixture an~ the amount of admi~ture within the specified range to be added ~o the concrete with the job materials at hand is de~mined by tests that simulate the ambient conditions and construction procedures to be encountered on the construction job. Conventional tests are employed to indicate the effect of the admixture on the concrete inso~ar as pertinent to the job with respect to air content of the concrete, consistency, bleeding of water and possible loss of air from fresh concrete~ rate of hardening, compressive and fle~ural strength, resistance to freezing and thawing, shrinkage on drying and permissible chloride con~ent.
The conventional addition of high-rangP and ordinary wate,-reducing agents frequently cause the concrete batch to bleed excessively and segregate as indicated by a thin watery paste wh~ch fails to hold the coarse aggregate particles in suspension. It is also kno~ that most high-range and ordinary water-reducing agents tend to e~ec~
plasticization by reducing the sur~ace tension of the water component of the concrete mi~ture. This may resul~
~:Z20793 in s~p~rati~n oE coarse aggreg~te particles ~nd result in low Ereeze-tha~ resis~ance, 109s oE pumpability, poor abrasion resistance, difficulty in the finishing operation and p~r surface texture in form work.
The addition of micro~ilica ~rom the admixture of the present invention with i~s high de~ree of fineness increases the surface area of the solids per unit of water volume, thus `-achieving better separation and suspension of coarse aggregate particles and results in increased plasticity and wo~ka~ility through change in particle interference. Since the mix~ure of cement, water and admixture of the invention contains more solids per unit volume, the paste is less wa~ery and less inclined to separate. Bleeding is thereby reduced by the microsilica by holding the water in paste. This results in a homogeneous, highly-wor~able, pumpable mixture with reduced bleeding characteristics.
Compressive strength achieved by concrete containing the admixture of the present i~vention is generally higher than one ~ould expect from the addition of increments of strength gained through the addition of each ingredient separately. The reason for this is not fully understoca bu~ it is believed that the high-range or ordinary water-reducing agent gives better distribution throughou~ the concrete mass to the microsilica particles and that certain synergistic effects e~ist between the admixture inoredients.
_ . ~
~220793 The a~ ture o.E the present inv~nti~n ;s use~ t~
adv~nta~e in conventional fresh concrete mixes and is mixed into the concrete mass using ~he conventional techniques now employed for mixing concre~e batches.
For example, an aqueous slurry admixture containing 45 pounds of microsilica, 8 pounds of dry Lomar ~ (high-rangP
water-reducing agent, sulfonated condensate of naphthalene and ~ormaldehydP) and 5.5 gallons of water may be added an~ mixed into a conventional fresh concrete batch containin~
450 pounds of Portland cement Type I without any other additives. The resulting concrete mixture at a water to cemRnt ratio of 0.35 by weight has good workability, consistency and no segregation in the fresh state. In the hardened stat(è, the 28 day compressive strength is typically unexpectedly high and of the order of 12jO00 p.s.i. and the freeze-thaw resistance is surprisingly high even in the absence o air entrainment. The concrete mixture contains 10% microsilica (dry) and about 1.8% of Lomar D
(dry) based on the weight of cement in the concrete mix.
The decreased permeability of the resulting mixture increases the resistànce to ingress o~ water an~
aggressive chemicals with a resulting improvement in freeze-thaw characteristics compared to concrete or mortar mixtures that do not include said microsilica aqueous slurry admixture.
~
The admixture o the pr~sent invention is premi~ed in optimum proporti~ns as determ~ned by standard industry tests to provide a single dispensing system as compared to con~enti~nal practice where three t~ four dispensing systems are required at the job site. Dispensing of all additives may be carried out simultaneously with the admixture of the present invention in ~hich the ingredients are in uniform and homogeneous dispersion as compared to the c~ventional practice ~f adding the separate ingredients sequentially in order to avoid flocculation. The admixture of the invention saves on truck loading time and reduces error in that only one batch ~ddition is required rather than three or four. Storage facilities are xeduced and quality control is increased by having a single manu~acturer supply all àdditives ;n the single admixture of the present invention which eliminates the problem of storage tank contamination. Another advantage of the aqueous slurry ~orm of admixture of the present invention is that it eliminates fine particle dust at the Job site. Although on smaller jobs, the dxy particulate admixture may be packaged in 80 to 100 pound bags and delivered to the job site.
The ability of the admixt~re of the present invention to impart inc~eased sulfate resistance and inoreased resistance to alkali-silica reaction in concrete containing it, will be realized ~rom the beneicial efects of micro-silica added to th~ concrete mi~ture.
~23 i2:~0793 Since the admixture of tll~ present inv~ntion may be used in conditions which may length~n setting time to an objectionable ~egree, accelerating ingredients may be added to the admixture to provide optimum setting and early strength gain characteristics. Further, it may be desirable to retard the setting tLme of the fresh concrete 8S for example in a bridge deck so that hardening ta~es place after the placing and finishing operations are co-~3leted.
The admixture of the present invention is tail~r m~de with optimum ingredients and amounts of ingredients for the concrete to be used in the construction job at hand.
Any of the known additives conventionally used in batching concrete or mortar may be incorp~rated into the admixture of the present invention.
Accel~rators such as the kn~ calcium chloride, calcium nitrate and calcium formate may be incorporated into the admigture with the essential ingredients in amounts that are currently used in the industry as dete~mined by s~andard test ~or optimum quantity ~or the application at hand. One or more accelerators will comprise from about 5% to about 20~ by weight based on the weight of microsilica in the admixture.
Retarders such as sugar in the form of glucosè or sucrose conventionally used in concxete or mortar batches ~2~0793 may also be incorporated in the admixture in opti~um amounts as determined by standard testing. One or more retarders may be present in an am~unt o~ from about 5~/O
~o about 20% by weight based on the weight ~E microsilica in the admixture.
If desired, air entraining agents such as Vinsol resin or Darex which is a sulfonated fatty acid derived from fats and greases may be incorporated into the 2 m;xture of the present invention in those particular 2?plications where a given level of entrained air may be a desirable characteristic. One or more air entraining agents may be pxesent in an amount of from about 0.5yo to about 2% by weight based on the weight of microsilica.
Any one or more additives alone or in combination with other additives may be incorporated with the essential ingredients in the admixture of the present invention. Compatibility and consistency of the admixture is determined by routine standard testing as well as the final effect on the particular concrete or mortar batch to be used in the construc~ion job at hand.
The admixture of the present invention may con~ain various proportions of the selected ingredients but in order to realize the beneit o the present in~ention, the amount of admixture mixed into a conventional fres~
TRA~ ~RQ~
1220'793 concrete ba~ch ~ill be sufficient to provide from ~bout `2.0% to abou~ 100% by weight of m~crosilica based on the weight of cement and from about 0.1% to about 5% by weight o one ~r more of the high-range or ordinary water-reducing agents alone or in combination based on the weight of cement.
Water or an organic liquid compatible with fresh concrete is preferably added to the admixture in an amount su~ficient to provide a slurry with the essential ingredients ~niformly ~n~ homogeneously dispersed therein. Accelerators, retarders, air entraining agents and any other conventional additives a re mixed with the essential ingredients of the admixture of the present invention in an amount sufficient to provide the desired concentration in the fresh concrete batch. In all cases the optimum amount of ingredients present in the admixture of the present invention is determined by standard conventional testing under the simulated ambient conditions for the job m~terials at hand and construction procedures to be used.
It will be understood that it is intended to cover all changes and modifications of the pxeerred embodiment of the invention herein chosen or the purpose of illustration which do not constitute a departure rom the spirit and scope of the invention.
Claims (26)
1. A cement or mortar additive comprising an admixture of essential materials of at least one ingredient selected from the group of water-reducing agents and high-range water-reducing agents dispersed in microsilica in which said microsilica is present in said admixture in an amount of from about 30% to about 98% by weight and said at least one ingredient is present in an amount of from about 2.0% to about 50% by weight based on the weight of microsilica.
2. The admixture of claim 1 slurried in at least one liquid selected from the group of water and an organic liquid to provide from about 20% to about 80% by weight of solids in said slurry.
3. The admixture of claim 1 which includes one or more water-reducing agents and one or more high-range water-reducing agents.
4. The admixture of claim 1 which includes one or more accelerators, one or more retarders and one or more air entraining agents alone or in combination therein.
5. The admixture of claim 1 in which the microsilica is obtained from the off-gas of an electric furnace used to produce ferrosilicon or silicon metal.
6. A cement or mortar additive comprising an aqueous slurry containing the essential materials of at least one ingredient selected from the group of water-reducing agents and high-range water-reducing agents dispersed in the slurry and mixed with microsilica having a slurry solids content of said microsilica and at least one ingredient of from about 20% to about 80% by weight (dry basis) of which the microsilica is present in an amount of at least about 10%
by weight of the solids content of said slurry and in which the said one ingredient is present in an amount of from about 0.4% to about 40.0% of the solids content therein.
by weight of the solids content of said slurry and in which the said one ingredient is present in an amount of from about 0.4% to about 40.0% of the solids content therein.
7. The aqueous slurry of claim 6 having a pH of from about 3.0 to about 7.5.
8. The aqueous slurry of claim 6 in which the micro-silica and said at least one ingredient are uniformly and homogeneously dispersed in suspension in said slurry.
9. The aqueous slurry of claim 6 which includes one or more water-reducing agents and one or more high-range water-reducing agents.
10. The aqueous slurry of claim 6 in which the microsilica is obtained from the off-gas of an electric furnace used to produce ferrosilicon or silicon metal.
11. The aqueous slurry of claim 6 which includes one or more conventional additives in addition to said at least one ingredient in said slurry admixture.
12. A hardened concrete structural element which is formed of conventional concrete batch materials to which has been added an admixture comprising the essential materials of at least one ingredient selected from the group of water-reducing agents and high-range water-reducing agents dispersed in microsilica in which said microsilica in said structural element is present in an amount from about 2% to about 100% by weight of microsilica by weight based on the weight of cement in said structural element and said at least one ingredient being present in said structural element in an amount from about 0.1%
to about 5.0% by weight based on the weight of cement in said structural element.
to about 5.0% by weight based on the weight of cement in said structural element.
13. The hardened concrete structural element of claim 12 which includes one or more water-reducing agents and one or more high range water-reducing agents.
14. The hardened concrete structural element of claim 12 in which the admixture added to said concrete includes one or more conventional concrete additives.
15. The process of forming a multicomponent admixture additive for concrete which comprises the steps of mixing one or more ingredients selected from the group of water-reducing agents and high-range water-reducing agents with microsilica and adding microsilica in an amount to provide from about 30% to about 98% by weight of microsilica in said admixture and adding from about 2.0% to about 50% by weight based on the weight of microsilica of said at least one ingredient in said admixture and continuing said mixing until the said at least one ingredient is uniformly dispersed in said microsilica.
16. The process of forming a multicomponent admixture additive for cement which comprises the steps of mixing one or more ingredients selected from the group of water-reducing agents and high-range water-reducing agents with water and with microsilica, adding said microsilica to said aqueous slurry in an amount to provide from about 10% to about 80% by weight of microsilica is said aqueous slurry and adding said at least one ingredient in an amount to provide from about 0.5% to about 40% by weight (dry weight) of said at least one ingredient in said aqueous slurry.
17. The process of claim 15 which includes the step of adding said admixture to a conventional concrete batch in an amount sufficient to provide from about 2% to about 100% by weight of said microsilica based on the weight of cement in said concrete and from about 0.1% to about 5.0% by weight of said at least one ingredient based on the weight of cement in said concrete batch.
18. The process of making an improved fresh concrete batch which comprises the steps of forming a multicomponent admixture by combining and mixing at least one ingredient selected from the group of water-reducing agents and high-range water-reducing agents with water and with microsilica, adding said aqueous slurry admixture to a conventional concrete batch of fresh concrete in an amount sufficient to provide from about 2% to about 100% by weight of said microsilica based on the weight of cement in said concrete and from about 0.1% to about 5.0% by weight of said at least one ingredient based on the weight of the cement and mixing the fresh concrete and aqueous slurry admixture to distribute the admixture ingredients therein.
19. The process of claim 18 which includes the step of adjusting the pH of the aqueous admixture to about 3.0 to about 7.5 during the mxing thereof.
20. The process of claim 18 which includes the step of continuing to mix the aqueous slurry admixture ingredients until the microsilica and at least one ingredient are uniformly and homogeneously dispersed in intimate contact therein.
21. The process of claim 18 which includes the step of adding and mixing one or more additional conventional additives into said aqueous slurry admixture.
22. The process of claim 21 in which the one or more conventional additives is selected from the group of conventional retarders and air entraining agents.
23. An aqueous slurry comprising microsilica stabilized against gellation with at least one or more ingredients selected from the group of water-reducing agents and high-range water-reducing agents which said at least one ingredient is present in said slurry in an amount from about 0.1% to about 10% by weight (dry basis) based on the weight of microsilica in said slurry.
24. The aqueous slurry of claim 23 which includes one or more high-range water-reducing agents and one or more water-reducing agents.
25. The process of claim 16 which includes the step of adding one or more high-range water-reducing agents and one or more water-reducing agents to said aqueous slurry.
26. An aqueous slurry comprising from about 5%
to about 80% by weight of microsilica stabilized against gellation with at least one or more ingredients selected from the group of water-reducing agents and high-range water-reducing agents which said at least one or more ingredients being present in said slurry in an amount from about 0.1% to about 10% by weight (dry basis) based on the weight of microsilica in said slurry.
to about 80% by weight of microsilica stabilized against gellation with at least one or more ingredients selected from the group of water-reducing agents and high-range water-reducing agents which said at least one or more ingredients being present in said slurry in an amount from about 0.1% to about 10% by weight (dry basis) based on the weight of microsilica in said slurry.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NO824100A NO153566B (en) | 1982-12-07 | 1982-12-07 | ADDITIONAL MIXTURE FOR CONCRETE AND MORTAL, PROCEDURE FOR PREPARING THE MIXTURE, AND USE THEREOF. |
| NO82.4100 | 1982-12-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1220793A true CA1220793A (en) | 1987-04-21 |
Family
ID=19886842
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000431892A Expired CA1220793A (en) | 1982-12-07 | 1983-07-06 | Concrete additive comprising a multicomponent admixture containing microsilica, its method of manufacture and concrete produced therewith |
Country Status (24)
| Country | Link |
|---|---|
| JP (1) | JPS59111963A (en) |
| AU (1) | AU548303B2 (en) |
| BE (1) | BE898398A (en) |
| BR (1) | BR8306701A (en) |
| CA (1) | CA1220793A (en) |
| CH (1) | CH658854A5 (en) |
| DD (1) | DD212953A5 (en) |
| DE (1) | DE3343948A1 (en) |
| DK (1) | DK165782C (en) |
| ES (1) | ES8505904A1 (en) |
| FI (1) | FI72962C (en) |
| FR (1) | FR2537127B1 (en) |
| GB (1) | GB2131409B (en) |
| IS (1) | IS1547B (en) |
| IT (1) | IT1167273B (en) |
| MX (1) | MX157587A (en) |
| NL (1) | NL190550C (en) |
| NO (1) | NO153566B (en) |
| NZ (1) | NZ206493A (en) |
| PH (1) | PH19938A (en) |
| PL (1) | PL244938A1 (en) |
| PT (1) | PT77741B (en) |
| SE (1) | SE460288B (en) |
| ZA (1) | ZA838678B (en) |
Families Citing this family (41)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6033242A (en) * | 1983-08-01 | 1985-02-20 | 出光石油化学株式会社 | Cement additive |
| GB2148871B (en) * | 1983-10-31 | 1987-01-07 | Pilkington Brothers Plc | Sheet material of fibre-reinforced cement |
| JPS61117143A (en) * | 1984-11-13 | 1986-06-04 | 電気化学工業株式会社 | Slurry silica fume for admixing cement |
| JPS61151056A (en) * | 1984-12-21 | 1986-07-09 | 電気化学工業株式会社 | Processing machine body |
| JPS61281057A (en) * | 1985-06-06 | 1986-12-11 | 日鐵セメント株式会社 | Composition for high strength high endurance mortar concrete |
| DK361785D0 (en) * | 1985-08-08 | 1985-08-08 | Aalborg Portland Cement | FORMED ITEM |
| NO158499C (en) * | 1985-09-03 | 1988-09-21 | Elkem As | HYDRAULIC CEMENT SUSPENSION. |
| CH667096A5 (en) * | 1985-11-22 | 1988-09-15 | Sika Ag | METHOD FOR PRODUCING A BUILDING AND / OR CONSTRUCTION MATERIAL. |
| DE3703762A1 (en) * | 1986-02-13 | 1987-08-20 | Hochtief Ag Hoch Tiefbauten | Process and spray device for applying a sprayed (gunned) concrete coat |
| ZA873180B (en) * | 1986-05-13 | 1987-10-28 | W.R. Grace & Co. | Microsilica slurries and method of preparation |
| US4888058A (en) * | 1986-09-29 | 1989-12-19 | W. R. Grace & Co.-Conn. | Silica fume slurry |
| EP0263606A3 (en) * | 1986-09-29 | 1988-08-31 | W.R. Grace & Co.-Conn. | Silica fume slurry |
| NO162848C (en) * | 1987-09-11 | 1990-02-28 | Elkem As | PROCEDURE FOR ADDING SILICA DUST TO A DRY SPRAYTE CONCRETE MIXTURE. |
| FR2621036B1 (en) * | 1987-09-25 | 1992-11-06 | Bouygues Sa | GROUT CEMENT BASED, MIXTURES OF ADJUVANTS FOR THE PREPARATION OF THIS GROUT AND APPLICATIONS |
| NO165021B (en) * | 1987-11-09 | 1990-09-03 | Norsk Hydro As | HYDRAULIC HEAVY WEIGHT CEMENT SUSPENSION SPECIFICALLY USED FOR CEMENTING OF OIL / GAS BURNER AND PROCEDURE FOR THE PREPARATION OF THE SUSPENSION. |
| NO165673C (en) * | 1987-11-16 | 1991-03-20 | Elkem As | HYDRAULIC CEMENT SUSPENSION. |
| US4829107A (en) * | 1988-02-24 | 1989-05-09 | W. R. Grace & Co.-Conn. | Rice hull ash concrete admixture |
| GB8904273D0 (en) * | 1989-02-24 | 1989-04-12 | Sandoz Ltd | Improvements in or relating to chemical compounds |
| EP0441924B1 (en) * | 1989-09-07 | 1994-06-01 | Holderchem Holding AG | Stabilised-viscosity adhesive agent and mortar additive and process for making it |
| GB2241499B (en) * | 1990-03-03 | 1994-09-21 | Sandoz Ltd | Concrete spraying process |
| DE4041828A1 (en) * | 1990-12-24 | 1992-07-02 | Degussa | METHOD FOR PRODUCING AND PROMOTING AN AQUEOUS SILICON SUSPENSION |
| JP2509408B2 (en) | 1991-07-19 | 1996-06-19 | インターナショナル・ドーム・システムズ・（サイプラス）・リミテッド | Method for producing hollow self-supporting mortar or concrete structure |
| EP0549595B1 (en) * | 1991-07-19 | 1996-12-11 | International Dome Systems Cyprus Ltd. | Method of manufacturing a hollow self-supporting concrete structure |
| US5250113A (en) * | 1991-07-31 | 1993-10-05 | W. R. Grace & Co.-Conn. | Dry castable concrete compositions and methods of preparing and dry casting the same |
| NO920758D0 (en) * | 1991-09-25 | 1992-02-26 | Takenaka Corp | HYDRAULIC SUBSTANCE |
| DE4208047C1 (en) * | 1992-03-13 | 1993-11-11 | Buderus Guss Gmbh | Mortar mixt. for sheathing metal pipes - contg. addition of micro-silica to improve handling characteristics |
| FR2693128B1 (en) * | 1992-07-03 | 1994-07-22 | Axim | PROCESS FOR DENSIFICATION OF ULTRAFINE POWDERS, ITS APPLICATIONS, AND PRODUCTS OBTAINED BY THIS PROCESS. |
| DE4227417C1 (en) * | 1992-08-19 | 1993-12-09 | Holderchem Betec Gmbh | Cement mix for injection into very long annular gap, e.g. for sewer repair - contains Portland cement, liquidiser and lead cpd. to stabilise viscosity without impairing green strength and final strength |
| NO177865C (en) * | 1993-07-27 | 1995-12-06 | Elkem As | Method of producing white microsilica |
| US5554352A (en) * | 1995-05-09 | 1996-09-10 | Construction Material Resources | Processed silica as a natural pozzolan for use as a cementitious component in concrete and concrete products |
| FR2770517B1 (en) * | 1997-11-03 | 1999-12-03 | Bouygues Sa | WELL CEMENTING DAIRY, ESPECIALLY AN OIL WELL |
| RU2160723C2 (en) * | 1998-11-25 | 2000-12-20 | ООО "Предприятие Мастер Бетон" | Method of preparation of concrete complex modified and concrete complex modifier(versions) |
| RU2152914C1 (en) * | 1999-02-09 | 2000-07-20 | Сытник Александр Александрович | Concrete composition |
| JP2002274913A (en) * | 2001-03-13 | 2002-09-25 | Asahi Kasei Corp | Production process of dehydrated, pressed formed product |
| DE102004033945B4 (en) * | 2004-07-14 | 2010-04-01 | Leipfinger Bader Kg | Mortar tape and method for its production |
| DE102005012740A1 (en) * | 2004-09-23 | 2006-09-21 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Airgel-containing fire protection material |
| US8980598B2 (en) | 2005-06-14 | 2015-03-17 | Danisco Us Inc. | Dry solids staging fermentation process |
| EA012025B1 (en) * | 2008-03-13 | 2009-06-30 | Открытое Акционерное Общество "Полипласт" | Complex additive for concretes and building mortars |
| EP2145868A1 (en) * | 2008-07-18 | 2010-01-20 | Lafarge | Aqueous formulations |
| RU2467968C1 (en) * | 2011-03-14 | 2012-11-27 | Роман Ринатович Сахибгареев | Complex additive for concrete, mortar and cement composites (versions) and method of producing said additive |
| RU2651848C1 (en) * | 2017-04-25 | 2018-04-24 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Петербургский государственный университет путей сообщения Императора Александра I" | Complex additive for foam concrete mixture |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT273778B (en) * | 1966-05-05 | 1969-08-25 | Ytong Internat Aktiebolag | Process for the production of aerated concrete and / or foam-porosity |
| AT312490B (en) * | 1971-01-05 | 1974-01-10 | Sika Ag | High strength cement mix |
| JPS4837733A (en) * | 1971-09-18 | 1973-06-04 | ||
| JPS5133603B2 (en) * | 1972-08-16 | 1976-09-21 | ||
| JPS4945114A (en) * | 1972-09-06 | 1974-04-30 | ||
| DE2510224A1 (en) * | 1974-03-14 | 1975-09-25 | Alfong Betonhaerdningsmedel & | PROCESS AND ADDITIVES FOR MANUFACTURING CONCRETE OBJECTS |
| US4310486A (en) * | 1976-01-16 | 1982-01-12 | Cornwell Charles E | Compositions of cementitious mortar, grout and concrete |
| RO72773B (en) * | 1976-07-09 | 1984-03-31 | Aksjeselskapet Norcem | Process for preparing non-corrodible concrete compositions |
| SE418736B (en) * | 1976-12-23 | 1981-06-22 | Bofors Ab | WHEN IN THE MANUFACTURE OF A CEMENT USE, INCLUDING CEMENT, SAND AND THE WATER INITIATE A RECOVERY OF DISTRIBUTED AIR IN USE |
| JPS5442396A (en) * | 1977-09-10 | 1979-04-04 | Nittetsu Mining Co Ltd | Method of removing carbon from silica flour |
| US4272948A (en) * | 1979-08-13 | 1981-06-16 | Deere & Company | Oscillating knife cutting apparatus |
| SE427012B (en) * | 1979-08-16 | 1983-02-28 | Nielsen Hilmer R | PREPARATION COMPOSITION CONTAINING AN ALKALIE EXTRACT OF A LINGOCELLULO MATERIAL, PROCEDURE FOR ITS PREPARATION AND APPLICATION OF THE COMPOSITION FOR BUILDING ELEMENTS |
| EP0038126B1 (en) * | 1980-04-11 | 1984-08-22 | Imperial Chemical Industries Plc | Cementitious composition and cement product produced therefrom |
| US4321243A (en) * | 1980-08-05 | 1982-03-23 | Cornwell Charles E | Method of producing stabilized aqueous dispersions of silica fume |
-
1982
- 1982-12-07 NO NO824100A patent/NO153566B/en unknown
-
1983
- 1983-04-01 JP JP58055319A patent/JPS59111963A/en active Granted
- 1983-04-11 MX MX19724483A patent/MX157587A/en unknown
- 1983-07-06 CA CA000431892A patent/CA1220793A/en not_active Expired
- 1983-11-17 PH PH29851A patent/PH19938A/en unknown
- 1983-11-21 IS IS2867A patent/IS1547B/en unknown
- 1983-11-21 ZA ZA838678A patent/ZA838678B/en unknown
- 1983-11-25 PT PT7774183A patent/PT77741B/en not_active IP Right Cessation
- 1983-11-28 IT IT2391883A patent/IT1167273B/en active
- 1983-11-30 FR FR8319158A patent/FR2537127B1/en not_active Expired - Lifetime
- 1983-12-01 FI FI834404A patent/FI72962C/en not_active IP Right Cessation
- 1983-12-05 DE DE19833343948 patent/DE3343948A1/en active Granted
- 1983-12-05 GB GB8332361A patent/GB2131409B/en not_active Expired
- 1983-12-05 SE SE8306700A patent/SE460288B/en not_active Application Discontinuation
- 1983-12-06 DK DK560383A patent/DK165782C/en active
- 1983-12-06 PL PL24493883A patent/PL244938A1/en unknown
- 1983-12-06 DD DD83257558A patent/DD212953A5/en unknown
- 1983-12-06 ES ES527825A patent/ES8505904A1/en not_active Expired
- 1983-12-06 NZ NZ206493A patent/NZ206493A/en unknown
- 1983-12-06 BE BE0/212004A patent/BE898398A/en not_active IP Right Cessation
- 1983-12-06 NL NL8304193A patent/NL190550C/en not_active IP Right Cessation
- 1983-12-06 BR BR8306701A patent/BR8306701A/en not_active IP Right Cessation
- 1983-12-07 AU AU22159/83A patent/AU548303B2/en not_active Ceased
- 1983-12-07 CH CH6557/83A patent/CH658854A5/en unknown
Also Published As
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1220793A (en) | Concrete additive comprising a multicomponent admixture containing microsilica, its method of manufacture and concrete produced therewith | |
| US5843216A (en) | Concrete additive comprising a multicomponent admixture containing silica fume, its method of manufacture and concrete produced therewith | |
| AU601137B2 (en) | An improved rice hull ash concrete admixture | |
| US5472499A (en) | Lightweight cementitious formulations and processes | |
| US4501830A (en) | Rapid set lightweight cement product | |
| EP1183217B1 (en) | Improved cement-based compositions | |
| Douglas et al. | Alkali activated ground granulated blast-furnace slag concrete: preliminary investigation | |
| EP0470829A1 (en) | Method for modifying concrete properties | |
| CN100366564C (en) | Particulate additive for dispersing admixtures in hydraulic cements | |
| US4126470A (en) | Light concrete and method of preparing the same | |
| JPS6197381A (en) | Injectable curable fine grout | |
| EP1176124B1 (en) | Inorganic cohesion agent for self-compacting cement pastes | |
| US5275652A (en) | Concrete additive comprising a multicomponent admixture containing silica fume, its method of manufacture and concrete produced therewith | |
| EP0498815B1 (en) | Process for producing an active fine aggregate for the preparation of concrete | |
| Pistilli et al. | Properties and possible recycling of solid waste from ready-mix concrete | |
| US3951674A (en) | Concrete additive | |
| Copeland et al. | Ultra fine fly ash for high performance concrete | |
| EP0434274A2 (en) | Injectable grout | |
| SU1399296A1 (en) | Method of preparing concrete mix | |
| PRASANTH et al. | A STUDY ON MECHANICAL AND DURABILITY PROPERTIES OF CONCRETE BY PARTIAL REPLACEMENT OF NATURAL ZEOLITE IN CEMENT | |
| St John | 7 THE DISPERTION OF SILICA FUME | |
| SU1239117A1 (en) | Raw mixture for producing cellular concrete | |
| SU1698218A1 (en) | Mixture for manufacturing wall panels | |
| SU1661172A1 (en) | Method of producing concrete mix | |
| Budge | The Influence of Water-Reducing Admixtures on the Curing of Concrete |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |