FI65770B - FRAMEWORK FOR FRAMING PROCESSING - Google Patents

Description

RjSCT ΓβΊ ^ ADVERTISEMENT, ULKAISU srrjnn jjegTL lbj O ') utlAggningsskrift 6 5 770 • (45) ^ (51) Kv.Hu/lm.a.3 C 04 B 13/26 FINLAND — FINLAND (2.1) ρμ «μμ5Μα (793452 (22) HilwhpUv »- ΑηΛΜαρΛ» § 05.11.73 (23) ANnpOvi — Glkighetsdag 05.11.79 (41) Tulkit JulklMfciJ - BHvftaffencNg gg Γ *** "" «· i * --- i — r - t-- ----

Patent- h mltentynhl AnMctn «1 * 4 od» ucUkrtfun pubflcarad 30.03.84 (32) (33) (31) PnrtMtr atuollnii · —teglrd priortMc (71) Flowcon Oy, Valkeakoski, FI; Sperring, 02400 Kirkkonummi, Finland-Finland (72) Bengt Forss, Pargas, Finland-Finland (74) Seppo Laine (54) Method for the production of a binder for concrete production - Förfarande för framställning av bindemedel för betongfram- The present invention relates to a method according to the preamble of claim. In the following, cement generally refers to a binder that is not limited to ordinary Portland cement or its derivatives.

Low water / cement ratio, in turn, means values <0.4-.

The weaknesses of the current, ordinary Portland cement concrete are e.g. high cost of binder, large deformations of concrete and poor corrosion resistance. The latter weakness is partly due to the fact that the hydration of the cement releases a large amount of lime, which already reacts with weak acids, CaCOH 2 · This amount can rise to almost a quarter of the total binder, so concrete in acidic soils must be protected from corrosive acid.

2 65770

In part, the poor corrosion resistance of concrete is due to its high porosity, which in turn is due to the large amount of water used in the mixing or, in the case of rigid concrete masses, the lack of compaction. The amount of water required for complete hydration of the cement is about 23 # by weight of the cement, while in practical concreting more than twice the amount of water is often used. In addition, in cement-rich concrete mixes, high heat of hydration can lead to stresses and cracks, resulting in poor corrosion resistance.

The sulphate resistance of ordinary Portland cement concrete is also poor due to the high A ^ O ^ content of the cement, so it is often necessary to use more expensive, sulphate-resistant special cement for concrete structures in sulphate-containing environments.

Attempts have been made to eliminate or reduce the above-mentioned weaknesses and difficulties, as long as the current cement has been in use, by adding less lime-containing, industrially produced or naturally derived hydraulic materials to the cement or concrete, pozzolans at a price significantly lower than that of cement and sulphate resistance is better and heat of hydration lower than that of normal cement due to lower lime content and reaction rate. The increased use of these admixtures has been mainly limited by their slow hydration and curing, leading to poor early strengths and contrary to the objectives of current industrial concrete production.

The main alloying element for Portland cement is blast furnace slag from iron production. In industrialized countries, this by-product or waste is generated in such large quantities that it is difficult to find use for it. In some countries, the use of slag is common, but the amount used is still small compared to the amount of cement clinker used. The most common amount of slag cement slag is about 30 ·· .50 # · The hydraulic properties and reactivity of the slag depend mainly on the alkalinity of the slag, i. the ratio of the amount of its basic components to the amount of acidic components. According to the following equation, the so-called F-value is often used to express the reactivity of the slag Ca0 + CaS + 1 / 2MgO + klOO F-value = -, -. .. - r

S1O2 + MnO

When the F value is> 1.9, the slag is highly reactive, while when the F value is <1.5, the slag is slow and weak. The hydraulic properties of the slag are also directly dependent on the glass content of the slag, which in good slag must be above 95 # · The higher 3 65770

The Al 2 O 3 content8 is, the better the strength properties of the slag, although the amount of Al 2 O 3 hydration compounds does not directly give strength.

The slowness of hydration and curing due to the chemical composition and physical properties of the slag can be eliminated by grinding the slag very finely. It has been observed that the strength of slag cement increases rapidly as a function of fineness. However, due to its high glass content, the slag is difficult to grind and the required grinding energy can double that of cement clinker.

Acceleration of slag hydration is also achieved by various accelerators, the best known of which are: - cement clinker, - various sulphates such as anhydrite and gypsum, - slaked or quicklime, and - bases and alkaline salts.

Of these accelerators, cement clinker and Anhydrite and Clinker together are the most commonly used.

Due to its slow reaction, slag cements have found use mainly as so-called low-temperature cement in monolithic concrete castings to reduce the risk of cracking.

In power plants, fly ash from the combustion of coal, peat and other fuels has also been used as an active filler material for low-temperature cement and concrete. Fly ash is usually a hydraulic alloy that reacts more slowly than slag, which is due to e.g. its low lime content, and its hydraulic properties are usually improved by adding to it lime-containing alloying elements, Kite fine lime and clinker, and grinding it even finer. The composition and hydraulic properties of fly ash are due not only to the fuels used but also to the conditions prevailing during combustion. The fineness of fly ash can be in the order of cement.

The object of the present invention is to obviate the above-mentioned drawbacks and to provide a process by which high-quality, fast-curing binders can be prepared from industrial by-products and wastes as well as from natural patients.

The invention is based on e.g. to the following thoughts:

It has been found that, in addition to the higher tempering temperature, the use of certain types of additives has a very advantageous effect on the hydration of the slag, as a result of which not much clinker is required, and in some cases not at all.

4 · 65770

It is known that slag reacts more slowly than clinker but that the final strength of concrete based on both binders is equal.

The hydration of slag and pozzolans can be substantially improved by the use of liquefiers such as lignosulfonate or sulfonated lignins, whereby the water-cement ratio of the concrete can be considerably reduced. By adding various accelerators, such as alkali carbonates and / or hydroxides, high-slag binders can also be used in fast-reacting cements. This beneficial effect is likely based on an increase in pH, which activates the slag or pozzolan, while enhancing the effect of the liquefier.

It has been found that the slower the nature of the reactive hydraulic binder, the more favorable the effect, and the more finely ground the binder. The slag thus begins to react in the same way as cement when some early carbonate or hydroxide is added which acts as an exciter.

Thus, it can be said that a liquefier (e.g., lignosulfonate) and a stimulant (e.g., NaOH and / or Na 2 CO 2) together act as potent liquefier combinations.

It is also known that the reaction takes place faster if the reaction temperature is raised, e.g., 4-0-90 ° C.

It is known that cement clinker should not be ground above a certain limit because the additional fineness does little to improve the curing and strength properties. Instead, it is advisable to grind the slag, for example, to a fineness of 4Ό0 ... 800 m ^ / kg.

Grinding additives known per se and additives which improve the workability of the binder (e.g. anti-vaulting agents) or the properties of the concrete made therefrom (e.g. deaerators, etc.) can be added to the grinding.

PI patent application 761072 discloses how alkali's carbonate is added to cement to produce a flowable cement mass.

FI patent application 7917 ^ 7, on the other hand, describes a method in which slag is used as a raw material for the binder. In road slag, the ratio of the total amount of alkaline earth metals to its amount of silica is typically in the range of 2.0 to 4.3 ·. In nickel slag, the corresponding ratio is typically 0.25 · Based on this publication, it is known per se to add various additives during grinding.

5,65770

The method according to the present application is based on the fact that, on the one hand, at least some of the additives are added during grinding and, on the other hand, the ratio mentioned in the previous paragraph is adjusted to 1.1 ... 1.6 by changing the slag and clinker proportions.

More specifically, the method according to the invention is characterized by what is set forth in the characterizing part of the claim.

According to the invention, it is also possible to use slag and pozzolanic substances for the production of fast-curing concrete if strongly basic additives (e.g. Na 2 CO 3, NaOH, etc.) are used in addition to the liquefier.

U.S. Pat. Nos. 3,960,582, 3,959,004 and 4,032,351 recommend the use of NaHCO 3 and other bicarbonates in addition to a liquefier to provide flexible concrete.

However, experiments have shown that the use of bicarbonates in binder mixtures containing a lot of slag and pozzolans is not advantageous due to their low pH (cf. EXAMPLE 1). The use of bicarbonates results in too slowly stiffening and hardening concrete, the hydration of which cannot be sufficiently accelerated even by heat treatment.

EXAMPLE 1

Slag clinker cement 70/30 was used as a binder, where the specific surface area of both components was 500 m / kg. The amount of binder was 400 kg / m3. Strengths (MN / m2)

Lignosulf. Accelerator V / S number 9 h 1 day 7 days (g) ___ 1.5 1.6 # Na 2 CO 5 0.387 33 38 42 1.5 1.3% NaHCO 3 0.415 30 35 39 1.5 1.5 # KHCO 3 0.387 23 26 34 1.5 2.1 # K2CO5 0.385 27 32 34

0.1 # Tributyl phosphate (TBP) was added to the concrete and the heat treatment took place at 70 ° C.

EXAMPLE 2

When slag alone is used as a binder, the effect of alkalinity on both liquefaction and strength development becomes even more apparent, as can be seen from the following table.

(Slag with a specific gravity of 400 kg / m 2 and a specific surface area of 470 m / kg was used as a binder. The deaerating agent was TBP 0.1 #. The concrete was hardened at a temperature of 70 ° C.) 6 65770 p

Strengths (MN / m ')

Liquidant Amount Accelerator Amount V / S Spread 6h 9h 3days 7days _w__m_______

Lignosulf. 1.5 Ns ^ CO ^ 3.0 0.38 6 18 20 26 28 "1.5 NaHCO2 2.4 0.40 9.0.7 6 9 13" 1.5 NaOH 1.0 0.365 23 13 14 15 18 "1.5 NaOH 2.0 0.325 20 19 21 29 30" 1.5 NaOH 3.0 0.335 19 29 33 34 35

Depending on the concreting conditions and the requirements for the properties of the concrete mass and hardened concrete, different combinations of additives can be applied to achieve the goal in the best possible economic way.

It is also known that strong and durable concrete is obtained by using as little water as possible in the manufacture of concrete and a binder which does not contain unnecessarily much lime.

Portland cement clinker uses a high degree of lime saturation to accelerate hydration reactions. When hydration is accelerated by heat, a low water-cement ratio, and various accelerators, a high degree of lime saturation has more disadvantage than benefit. In normal porous concrete, lime maintains a high pH, which protects the reinforcement from rust. In dense concrete, this is not necessary, but the total amount of alkaline earth oxides must be adjusted according to the SiO 2 content of the binder. When this ratio is about 1.2 ... 1.5, even with weaker hydraulic binders, such as slag and fly ash, thermal hardening achieves strengths that correspond to those achieved with the best cements.

EXAMPLE 3

Satisfactory strength is not achieved with fly ash alone, although it is activated with a base, nor with a 2: 1 slag-fly ash mixture. If the amount of fly ash is reduced to 10 #. the above molar ratio is achieved, which is also shown by the development of strength in the following table. The 2: 1 slag-ash mixture requires about 10% lime addition to achieve this molar ratio, whereby the strengths are greatly improved. With a higher addition of lime, the strengths decrease again.

7 65770

M

Fh> ti \ O D'- / "> [N Γ ΙΛ ΙΛ

OJ

S ---

\ M

^> ON O (M IS N (\ 1

NN CM NN AND NN NN

-P ___ (L> n λ o- cnj ^ o

3 4 · OJ (Μ UN NN (M

3 ON

• o, ____ _______________________________,

k1J3 KN v l £) KN l £> O

OJ NN CM OJ

ω: cö

• H r * O cO IN ON £ N

> OJ OJ v r- v 0)

Hl Φ Ό

left LA O O UN UN O

3 O r- V f d · LO

ffl KN KN fA KN KN KN

I ·· * ·% ** # * Ψ »0» CO o o o o o o \> Ö

•B

£ g o o o o o o · ζ | r # * # »·» f · r

.3¾ CN NN OJ KN CN CN

Ή W'- '

"B

pH

3

0JH> O IA CO LA IA UN

Q ^ # · r> e f> r «« βν / oj r · O v r * r * bo

•B

Hl a s e

"$ R

O O O

V OJ KN

<i <J <j <i C <* h & (h h h

Pf Λ | l) h 1 ^ P <

VTL Vfl Vft SA Vft VA

gs (a. On On On

8KN O O O- KN

KN r- KN OJ CM

• H «W M W W

© 1R 1R «1R 1R

Ό • H [N- O O NN O- 03 UD ON CD UN * J- 8 65770 Here PFA - fly ash, K = slag, HK = fine lime. The amount of binder was 4-00 kg / m 2. 0.1% tributyl phosphate was added as deaeration pressure, and 0.1% Na-gluconate was added as a retarder. The tempering temperature was 70 ° C.

Claims (1)

Claim: A process for the preparation of a binder for the production of concrete with a low water / cement ratio, which process uses at least 50% by weight of slag, technical and / or natural pozzolans as the binder raw material, at least a part of which is ground to a fineness of> kOO m / kg, 0.2 to 3.0% by weight of at least one sulfonated polyelectrolyte is added to the raw material and a total of 1.3 to 8% by weight of at least one alkali hydroxide, preferably sodium hydroxide, and / or at least one alkali is also added to the raw material as a curing control. carbonate, preferably sodium carbonate, characterized in that at least some of the additives are added during grinding, and - the binder components are proportioned so that the ratio of the total amount of alkaline earth metals in the binder to its silica is 1.1 to 1.6, preferably 1.2 to 1 U.