FR2723582A1 - NEW AIR TRAINING AGENT. - Google Patents

Abstract

The subject of the invention is an aeration agent especially suitable for use with cementitious compositions comprising fly ash having high levels of residual carbon (loss on incandescence greater than 5%), this agent comprising a surfactant fatty acid-based active agent and a nonionic surfactant, the fatty acid-based surfactant (a) being chosen from C12-C24 alkanoic acids and their alkali metal salts, lower alkylamine and lower alkanolamine and the nonionic surfactant (b) being chosen from materials of formula Ph(R)-O-(-CH2 CH2 O-)-n H where Ph(R) means a phenyl group substituted by R, R means a C8-C9 alkyl group and n means a number from 1 to 50.

Description

The present invention relates to the entrainment of air in

  cementitious compositions and the compositions used to produce such an effect.

  Cementitious compositions of the concrete, mortar and grout type sometimes need to be aerated, for example to improve their workability or to give them increased resistance to frost. This is commonly done by incorporating into the fluid composition an air entraining agent (hereinafter referred to as "EA agent"). The fact of mixing the cement composition causes the formation of bubbles; these are stabilized by the agent EA. These materials are themselves described in standard ASTM C 260 and the subject of ventilation is dealt with in detail in the literature (see for example "Concrete Admixtures Handbook", ed. Ramachandran

  (Noyes 1984). As examples of EA agents, mention may be made of surfactants

  active, esters of sulfuric acid and higher alcohols and alkyl sulfonates. While known EA agents have given excellent results with many known cementitious compositions, they are not effective in

  all cases. An example of their reduced effectiveness is their use in combination

  tion with cementitious compositions comprising fly ash. Fly ash is residue from industrial boilers fed with pulverized coal and is commonly used in cementitious compositions, for example as a permeability reducer. The problem with fly ash is that it contains proportions of residual charcoal (sometimes referred to as "unburned charcoal") that have withstood the combustion process. It is believed that this residual carbon is capable of absorbing EA agents and thus reducing their effectiveness. The problem is linked to two other factors: (i) the coal can be of very diverse origin, which means that the residual coal content will change from one batch to another, which makes it difficult to solve this problem , and (ii) environmental pressures have forced the burning of coal at low temperatures, leaving even more residual coal in

the fly ash obtained.

  Various attempts have been made to resolve this problem by developing particular EA agents. However, either the air entrainment properties of these EA agents are poor, or a high dose is required to

  obtaining their effect or both problems at the same time.

  We have now found that a particular mixture of materials can give an EA agent which not only has excellent air entrainment properties, but exhibits such properties at relatively low doses, even in the presence of fly ash. containing residual carbon. The present invention therefore relates to an air entraining agent comprising (a) a fatty acid-based surfactant and, (b) a nonionic surfactant, the acid-based surfactant fatty (a) being chosen from C12-C24 alkanoic acids and their alkali metal salts, the lower alkylamine salts and the lower alkanolamine salts and the nonionic surfactant (b) being chosen from materials of formula Ph (R) -O - (- CH2CH20 -) -. H o Ph (R) signifies a phenyl group substituted by R, R signifying an alkyl group

  in C, -C9 and n signifying a number from 1 to 50.

  According to a preferred aspect of the invention, the air entraining agent

  also comprises (c) a salt chosen from the group comprising alkyl-

  sulfonates, alkylarylsulfonates, sulfuric esters of higher alcohols and resinates. The fatty acid-based surfactant (a) can be chosen from the group of substances known in the art. The fatty acid chain of the surfactant (a) can be saturated or unsaturated, linear or branched. The fatty acid-based surfactants (a) can be fatty acids or preferably

  salts of such fatty acids, preferably salts of alkali metals or amines.

  The preferred alkali metal salts are those of sodium and potassium and the preferred amine salts are those of low-weight alkylamines and alkanolamines

  molecular, preferably the salts of triethylamine or triethanolamine.

  Preferred surfactants (a) include tallow fatty acid soap, oleic acid soap, linoleic acid soap and acid soap

  palmitic, tallow fatty acid soap being especially preferred.

  The nonionic surfactant (b) as defined above can be chosen from any one of these materials. The substituent R on the phenyl group can be linear or branched and preferably signifies an alkyl group.

  C8 or C9. As specific examples, mention may be made of polyoxyethyl ether.

  nique of nonylphenol and the polyoxyethylene ether of octylphenol. The number n of ethylene oxide units per molecule is between 1 and 50. It has been found that the value of na has an effect on the capacity of the EA agents of the invention to cause sufficient air entrainment. in the presence of fly ash with a high proportion of residual carbon. For use with such a material, the EA agent preferably comprises a surfactant (b)

  comprising from 20 to 30 units of ethylene oxide per molecule.

  The salts of component (c) of the agent EA of the invention can be

  chosen from a wide variety of suitable materials.

  The alkyl residues of the alkyl sulfonates and alkylarylsulfonates are generally C9-C12 and can be linear or branched. The salts are preferably alkali metal salts, especially the sodium and potassium salts or the triethanolamine salts. Specific types include the sulfonates of an aoolefin, alkylbenzenesulfonates and alkylsulfates. For higher alcohol sulfates, the alcohols must have at least 12 atoms

  carbon. The adducts of ethylene oxide from such alcohols are also

  mentally useful and, as suitable examples, there may be mentioned ether sulfates

  polyoxyethylenealkyl and sulfates of polyoxyethylenealkyl ether

  phenyl. Suitable resins include the resin soap obtained by

  saponification of pine resin with sodium hydroxide or hydro-

  potassium xyde and the sodium, potassium or triethanolamine salts of

abietic acid.

  The weight ratio of the individual components is between 10 and%, preferably between 10 and 80% (relative to the active material) for the surfactant (a), from 90 to 10% for the surfactant non-ionic active (b) and not more than 20% for component (c) when this material is present. The agent is used in a proportion of 0.001 to 0.1% by weight of the active material relative to the weight of the cement plus the agent EA. EA agents are generally used in the form of aqueous solutions. They can be used in combination with other agents known in the art such as water reducing agents, EA water reducing agents, superplasticizers (water reducers), superplasticizers (EA water reducers) , plasticizers, water repellents,

  anti-rust agents and shrinkage reducing agents.

  The EA agent of the invention is useful for aeration of cementitious compositions. f is particularly suitable when used in compositions containing materials comprising residual carbon. It is believed, without limiting the invention in any way, that the residual carbon absorbs the usual EA agents. Problems caused by fly ash materials are known from the Japanese industry standard JIS A 6201 which states that fly ash with an incandescent loss of more than 5% should not be used. However, the EA agents of the present invention can be used with fly ash having an incandescence loss greater than 5%. The invention therefore relates to a process for the preparation of an aerated cement composition containing fly ash, these fly ash having an incandescence loss greater than 5%, process according to which an air entraining agent is added as described more top to the cement composition containing fly ash. The invention also relates to an aerated cement composition containing fly ash having an incandescence loss greater than 5%, characterized in that it comprises an air-entraining agent such

as described above.

  The following examples illustrate the invention without in any way limiting it

carry her.

Example 1:

  1) Test method a: Concrete mixing method In a mixer, fine aggregates, cement and mixing water are introduced (comprising an EA water reducing agent and an EA agent of the invention) and mix for 30 seconds. We then introduce

  coarse aggregates and mixed for 90 seconds.

  b: Change of concrete as a function of time After measuring the slump height (according to JIS A 1101) and the air content (according to JIS A 1128) of the concrete mix, it is transferred to a mixer of the concrete mixer type with tilting drum and the mixture is stirred with a tilting angle of the drum of 15 degrees and a speed of rotation of the concrete mixer of 2 revolutions / min and the air content is measured at

  after 30 minutes and 60 minutes.

2) Materials used a: Cement

  Mix and use ordinary Portland cement (specific gravity

  cific = 3.16) including equal parts of ordinary Portland cements

  from Onoda, Sumitomo and Mitsubishi.

  b: Fly ash Commercial fly ash is used (specific gravity = 2.26, specific surface = 3410 cm2 / g, loss on glow = 3.9%, absorption

methylene blue = 0.9 mg / g).

  c: Fine aggregates Quarry sand from the Oi river is used (specific gravity = 2.64,

fineness module = 2.76).

d: Coarse aggregates

  We use crushed stone from Ome, Tokyo (maximum dimension

  male = 20 mm, specific gravity = 2.65, fineness module = 6.63).

e: Mixing water

Tap water is used.

  f: EA water reducing agent EA water reducing agent is used [name of the owner: "Pozzolith" (registered trademark) n 70] prepared by NMB Ltd. g: Agent EA The following agents are used: As surfactant based on fatty acid (a):

  - saponified tallow oil with potassium hydroxide.

  As nonionic surfactant (b): - the polyoxyethylene ether of nonylphenol comprising the addition of 10-, -, 25-, 30-, 40-, and 50 moles of ethylene oxide (designated below) after

  bl, b2, b3, b4, b5 and b6, respectively).

  As ingredient (c): - sodium dodecylbenzenesulfonate (hereinafter cl) - resin acid saponified with potassium hydroxide (hereinafter c2) - sodium sulfonate of an α-olefin (ci -after c3)

  - sodium sulphate of polyoxyethylene ether of nonylphenol (ci-

after c4).

  3) Proportion of concrete mix and test results The proportions of concrete mix are determined with a target sag height of 18 + 2 cm and a target air content of 5 + 0.5%, without addition of fly ash and with the addition of 20% ash

  fly as compared to the total amount of cement plus fly ash.

  The proportions of the mix are shown in Table 1.

Table 1

  Water Ratio Content - Content Report (kg / m3) ash binder sand - EC CV SG AREEA flying EJ (C + CV) aggregates CV / (C + CV) s / g (%) (%) 0 0.575 46 184 320 - 798 352 800ml 0.563 45 130 250 64 776 963 800 ml E: water; C = cement; CV = fly ash; S = sand (fine aggregates); G = gravel

  (coarse aggregates); AREEA = water reducing agent, air entrainer.

  Concrete is prepared according to the proportions of the mix and the air content and the changes in air content as a function of time are measured. The

  results are presented in Tables 2 and 3.

z // / / J /

Table 2

  Test Content on Agent úA Dosel) Rate of increase Changes in ash content Ingredients (%) of air as a function of v: lantel (a) (b) () dose2) time. () in.Z Rate Type Rate Type Rate in 20 min. 30 min. 60 mins. Example I 0 100 b3 0 none 0 0.0035 4.9 5.1 4.8 comparative 2 0 90 b3 10 "O 0.0035 4.8 4.7 4.6 3 0 75 b3 25" O 0.0035 5.1 4.9 4.6 4 0 50 b3 50 "0 0.0045 - 5.1 4.9 4.8 0 25 b3 75" 0 0.0050 5.2 4.8 4.3 6 0 10 b3 90 "0 0.0100 - 5.1 4.8 4.4 7 0 0 b3 100" 0 0.0170 - 5.2 4.5 4.2 8 0 0 b3 0 c2 100 0.0006 - 5, l 4.7 4.4 9 20 0 b3 0 c2 100 0.0040 667 5.0 3.0 2.4 20 100 0 none 0 0.0255 729 5.2 5.3 5.5 Example 11 20 90 b3 10 none 0 0.0250 714 5.3 5.0 4.8 oo 12 20 75 b3 25 "O 0.0210 600 5.4 5.2 4.9 13 20 50 b3 50" O 0.0165 367 510 4 , 8 4.6 14 20 25 b3 75 "O 0.0155 310 5.2 4.7 4.6 20 10 b3 90" 0 0.0160 160 5.4 5.1 4.6 Example 16 20 0 b3 100 none 0 0.0300 143 5.1 4.6 3.6 comparative Example 17 20 50 bl 50 none 0 0.0100 5.1 4.9 4.4 18 20 50 b2 50 0 0.0145 4.9 4, 7 4.5 19 20 50 b4 50 "0 0.0200 5.2 4.8 4.6 20 50 b5 50 0 0.0240 5.0 4.7 4.5 1 21 20 50 b6 50 0 0.0240 5.0 4.8 4.6 (1 Note 1) Dose of EA agent (solid matter) as a percentage by weight based on the weight of the cement or

  total amount of cement and fly ash.

  2) Dose of EA agent used with fly ash, relative to the dose when not used

  no fly ash, calculated as 100%.

  In tests 13 and 17 to 21 of Table 2, the number of ethylene oxide units added to the polyoxyethylene ether of nonylphenol is changed, namely 10 (bl), 20 (b2), 25 (b3 ), 30 (b4), 40 (b5) and 50 (b6), the surfactant (a) being kept constant. It is observed that the dose of EA agent tends to decrease when the number of ethylene oxide units decreases. In addition, since the solubility of the nonionic surfactant (b) decreases as the number of ethylene oxide units decreases, it is desirable for practical reasons that the number of oxide units d be understood

between 20 and 30.

  In tests 1 to 7, there is no addition of fly ash and when the amount of ingredient (b) increases, it is observed that the dose of EA agent necessary to obtain the targeted air content is superior compared to the case where there is no addition of ingredient (b) (test n 1). However, in tests 10 and 16 where fly ash is used, the dose of EA agent necessary to reach the target air content, when the amounts of ingredient (b) are between 10 and 90%, is lower compared to that required when the surfactant (a) is used alone (test No. 10) and when the nonionic surfactant (b) is used alone (test No. 16). The lowest dose is obtained

  when the ratio of the ingredients (a) to the ingredients (b) is 25: 75% by weight.

  This can be seen in Figure 1 showing a dose / composition graph.

  In tests 8 and 9, an EA (c2) agent of the commercial resinate type is used and although the targeted air content is obtained immediately after mixing, in the case of the addition of fly ash (test 9 ), content

  air is greatly reduced over time.

  Table 3 presents the results when sodium dodecylbenzenesulfonate (cl), resin acid saponified with potassium hydroxide (c2), sodium sulfonate of an α-olefin (c3) and sodium sulfate polyoxyethylene ether of nonylphenol (c4) are used in combination as ingredient (c) with ingredients (a) and (b). In tests 26 to 31 of Table 3, fly ash is added and the EA agents comprising these ingredients have excellent properties at low doses. In test No. 32, the resin acid saponified with potassium hydroxide is used with a ratio of

  % greater than the desired ratio, and the air content decreases over time.

J /

Table 3

  Test Content ea Agent HA Dosel) Rate of increase Changes in the ash content Ingredients () of the air depending on the flywheels (a) (b) (c) dose2) time (2) in 2 Rate Type Rate Type Rate in ZO min. 30 min. 60 mins. Example 22 0 40 b3 30 ci 10 0.0040 5.0 4t8 4.7 comparative 23 0 40 b3 50 c2 10 0.0040 4.8 4.6 4.4 24 0 40 b3 50 c3 10 0.0035 - 4 , 9 4.7 4.5 0 40 b3 50 c4 10 010040 4.6 4.4 4 # 2 Example 26 20 40 b3 50 cI 10 0.0140 350 5.1 5.0 4.7 27 20 35 b3 50 c2 S 0.0155 - 4.8 4.6 4.4 28 20 40 b3 50 c2 10 0.0145 413 4.9 4.8 4.6 29 20 45 b3 50 c2 15 0.0135 4, 7 4, 5 4.4 20 40 b3 50 c3 10 0.0140 414 4.9 4d7 4.5 31 20 40 b3 50 c4 10 0.0145 362 5.2 5.0 Example 32 20 25 b3 50 c2 25 0.0100 - 5.0 4.0 3.1 comparative Note 1) Dose of EA agent (solid matter) as a percentage by weight relative to the weight of the cement or

  total amount of cement and fly ash.

  2) Dose of EA agent used with fly ash, relative to the dose when t

  no fly ash, calculated as 100%.

in A_

Example 2:

  1) Test method a: Concrete mixing method as for Example 1 The subsidence height (according to JIS A 1101 standard) and the

  air content (according to JIS A 1128 standard) of concrete.

2) Materials used a: Cement

  Mix and use ordinary Portland cement (specific gravity

  cific = 3.16) including equal parts of ordinary Portland cements

  from Onoda, Sumitomo and Mitsubishi.

  b: Fly ash We use 8 lots (F1 to F8) of fly ash with different incandescence losses prepared in the same thermal power plant. Specific gravities, incandescence losses and absorption of blue

  methylene from these fly ash are shown in Table 5.

  c: Fine aggregates Quarry sand from the Oi river is used (specific gravity = 2.64,

fineness module = 2.76).

  d: Coarse aggregates We use crushed stone from Ome, Tokyo (maximum dimension = 20

  mm, specific gravity = 2.65, fineness module = 6.63).

e: Mixing water

Tap water is used.

  f: Agent EA The agents EA described below are used: - EA1 50% by weight of saponified tallow oil is mixed with potassium hydroxide as surfactant based on fatty acid (a) and 50% in

  weight of an adduct of the polyoxyethylene ether of nonyl-

  phenol having 25 ethylene oxide units as a surfactant not

ionic (b).

  - EA2 potassium hydroxide as a surfactant based on fatty acid (a), 60% by weight of polyoxyethylene ether of

  nonylphenol having 25 units of ethylene oxide as a surfactant

  non-ionic active (b) and 5% by weight of resin acid saponified with

potassium hydroxide.

  - EA3 An EA agent prepared by NMB Ltd. (owner's name: n 303A, with

  an alkylarylsulfonate as the main ingredient).

  - EA4 An EA agent for the fly ash of Toho Kagaku Kogyo (name of the

  owner: "Cemerol" T-80, with polyoxyethylene monooleate-

  sorbitan as main ingredient).

  3) Proportion of concrete mix and test results The dose of EA agent which gives an air content of around 5% is determined using the fly ash F4 having approximately an average loss on incandescence. This dose is used for other fly ash and

  measures changes in air content.

  The proportions of the mix when using fly ash representing 20% by weight relative to the total weight of the cement plus the fly ash are determined by test mixes. They are

shown in Table 4.

Table 4

  Water ratio content - Ratio content (kg / m3) ash binder sand - E C CV S G flys E / (C + CV) aggregates CV / (C + CV) s / g (%) (%)

0.60 45 180 240 60 788 981

  E: water; C = cement; CV = fly ash; S = sand (fine aggregates); G = gravel (coarse aggregate); The results of the tests are presented in Tables 5 and 6. As indicated in Table 5, while the air contents using EA1 are between 3.7 and 5.2% with a coefficient of variation of 10.0% and the air contents using EA2 are between 3.7 and 5.2% with a coefficient of variation of 9.8%, the air contents using EA3 are between 2.5 and 7.0% with a coefficient of variation of 35.2%, the air contents using EA4 are between 2.7 and 6.4% with a coefficient of variation of, 0%. In addition, when EA1 and EA2 are used, the variations in the air contents are extremely small and stable air contents are obtained with low doses, even if the loss on ignition of the fly ash varies. This contrasts with the results obtained when EA3 and EA4 are used, the variations

then being much superior.

Table 5: see next page

Table 5

  Example Comparative example Agent Type of EA. EA2 A3. ' EA Doge 1) 0.035% 0.029% 0.0075% 0.12% Cen- Loss Absorption from Orav. in the blue incarnation of Slump Air Slump Air Slump Air Slump Air vo- spic. mithylene descent (cm) (Z) (cm) (Z) (cm) (z) (cm) (Z) lantes (Z) (mg / g) batch Fl 2.21 6.84 0.77 15.0 5 , 2 15.0 5f0 15.5 6.8 16.0 5t7

  F2 2.18 7.16 1.12 15.0 5.1 14.5 5.2 14.5 7.0 14.0 5.1

  F3 2.16 7.75 0.85 14.5 4.6 14.0 5.1 15.0 6.5 11.0 3.7

  F4 2.15 8.04 0.87 14.0 5.0 14.0 5.0 13.5 4.3 17.0 5.5

  F5 2.17 8.42 0.85 13.5 5.1 13.0 5.2 14.5 4.8 15.0 6.4

  F6 2.20 8.60 1.11 13.0 5.2 13.5 4.6 13.0 3.5 13.5 4.9

  F7 2.20 9.06 0.73 13.5 4.6 13.0 4.6 12.0 2.8 11.5 4.4

  F8 2.20 10.51 1.29 13.0 3.7 13.5 3.7 12.0 2.5 9.5 2.7

  Average content (%) 4.8 - 4.8 - 4.8 - 4.8 air Deviation- (%) - 0.48 - 0.47 - 1.7 - 112 Dose type (%) - 1.5 - 1,5 - 4,5 - 3,7 Coefficient - 10,0 - 9,8 - 35,2 - 25,0 of variation Z Note 1) Dose of agent EA (solid matter) in percentage in poiis compared by weight of cement or

  total amount of cement and fly ash.

Table 6

  Agent Type EA Changes in ash air content over time (%)

Type Rate t (%) 0 60min.

Example F4 EA 1 0.0350 5.0 4.8 4.5

EA2 0.0290 5.0 4.9 4.6

Example

comparative EA3 0.0075 4.3 3.0 2.5

EA4 0.1200 5.5 5.0 4.7

  Note Rate of agent EA (solid matter) in percentage by weight compared to

  cement or the total amount of cement and fly ash.

  Table 6 presents the results of the tests of changes as a function of time of the air contents of the concretes using EA1, EA2, EA3 and EA4. The air contents of concretes using EA1 and EA2 indicate almost no loss even after 60 minutes. However, in the case of EA3, compared to EA1 and EA2, although the air can be entrained with a low dose, the reduction in air content after 60 minutes is considerable. In the case of EA4, although a reduction in air content after 60 minutes is

  low, the dose required is very high compared to EA1 and EA2.

Claims (10)

  1. An air entraining agent, characterized in that it comprises (a) a surface-active agent based on fatty acid and, (b) a non-ionic surface-active agent, the surface-active agent to fatty acid base (a) being chosen from C12-C24 alkanoic acids and their alkali metal salts, lower alkylamine salts and lower alkanolamine salts and nonionic surfactant (b) being chosen from materials of formula Ph (R) -O - (- CH2CH20 -) - oH o Ph (R) signifies a phenyl group substituted by R, R signifies an alkyl group   in C8-C9 and n means a number from 1 to 50.   2. An air entraining agent according to claim 1, characterized in that it also contains (c) a salt chosen from the group comprising the salts of alkylsulfonates, of alkylarylsulfonates, sulfuric esters of higher alcohols and the resinates.   3. An air entraining agent according to claim 1, characterized in that the fatty acid-based surfactant (a) is chosen from fatty acids or their salts.   4. An air entraining agent according to claim 3, characterized in that the alkali metal salts are those of sodium and potassium and the salts   amines are the salts of low molecular weight alkylamines and alkanolamines.   5. An air entraining agent according to claim 1, characterized in that   that the substituent R is chosen from octyl and nonyl groups.   6. An air entraining agent according to claim 1, characterized in that the number n of ethylene oxide units per molecule is between 1 and 50. 7. An air entraining agent according to claim 2, characterized in that   that the additive (c) is an alkali metal salt or a triethanolamine salt.   8. An air-entraining agent according to claim 1, characterized in that the weight ratios of the individual components are from 10 to 90% (relative to the weight of the active material) of surfactant (a), 90 to 10% of nonionic surfactant (b) and not more than 20% of component (c), when this last one is present.   9. A process for the preparation of an aerated cement composition comprising fly ash having a loss on incandescence greater than%, characterized in that an air entraining agent according to claim is added   1 or 2 to the cement composition comprising fly ash.   10. An aerated cement composition containing fly ash in which the fly ash has an incandescence loss greater than%, characterized in that the composition comprises an air-entraining agent such   as specified in claim 1 or 2.