SU1301808A1 - Method for preparing concrete mix - Google Patents

Abstract

The invention relates to the production of building materials to methods for the preparation of concrete mixture for the manufacture of monolithic and precast concrete structures. The invention is aimed at reducing the shrinkage of concrete and increase its strength. A method for preparing a concrete mix is to mix cement, aggregate, water, and additives based on phenol-formaldehyde resin. The additive is successively treated with bottoms from the production of caprolactam based on caprolactam monomer in an amount of 15-25% by weight of resin, then ammonium nitrate in an amount of 15-20% by weight of resin and crushed together with 18-43% by weight of total silica to the specific surface 1200-1400. The resulting additive is introduced into the concrete mixture in an amount of 0.15-0.3% by weight of cement. 4 tab. i (L 00 about 00

Description

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The invention relates to the production of building materials, to methods for preparing a concrete mix or mortar.

The purpose of the invention is to reduce shrinkage of concrete and increase its strength.

The phenol-formaldehyde resin used as an additive is the condensation product of phenol with formaldehyde in an alkaline medium with heating (temperature 80-90 ° C;) Ammonia water is used as an alkaline catalyst for the reaction of oxymethylation.

Thermosetting resin with a residue of 25% is modified by bottom residues of caprolactam production at the same temperature and under the same conditions for a short time (15-20 minutes) until lactam is completely exhausted. The amount of bottoms of caprolactam production is 15-25 mas. on 100 ma.ch. resin.

The bottoms of caprolactam production contain 62-95% of caprolactam monomer and 3-38% of oligomers (di- and trimers) of caprolactam. Up to 2% aminocaproic acid and up to 1% of oxidation products are present in the composition of bottoms. The nature of the effect of the bottoms of caprolactam is similar to the action of the monomer of caprolactam, in either case the interaction mechanism is as follows: the methylol groups of the phenolic resin CHjOH interact c. amino groups of caprolactam, caprolactam oligomers and aminocaproic acid.

Then the resulting resin is further modified with ammonium nitrate NH N0, j in the amount of 5--20 May. hours at 100 mach. resin. Modification also takes place under the same conditions for 20 minutes.

Quartz sand and polymer additive in the amount of 0.30-0.60% by weight of sand (in terms of dry matter) are loaded into the mill, then they are ground to a specific surface of 1200-1400. During the grinding process, the surface of the particles is activated by a polymeric additive.

The method of preparation of concrete mix.

Cement, polymer additive and node are sequentially loaded into the mixer. Then after nepodoljitel

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The main transfer (20 s):,) is loaded successively with small and large aggregates (sand and gravel). Next, the concrete mixture is moved for 100 s. The use of a separate method does not increase the total mixing time as compared with traditional technology, but it does allow to improve the microstructure of concrete.

The concrete mixes with the proposed additive are presented in Table 1 (the amount of bottoms of caprolactam is 15, 17, 20, 23 and 25%, respectively, by weight of resin for compounds 1 5; the amount of ammonium nitrate is 15, 15, 17, 20, respectively. and 20% by weight of the resin for compounds 1-5; the amount of quartz sand is between 1% (its sand weight is 18, 24, 30, 36 and 43%, respectively, for compositions 1-5).

The degree of grinding of the additive with quartz sand, respectively, on the compositions and 2 is 1200, for the composition 3 - 1300, and for the composition 4 and 5 - 1400.

In tab. 2 shows the control compositions of the concrete mix.

In tab. Figure 3 shows the known compositions of the concrete mix (the amount of bottoms of caprolactam is 15,17,20,23 and 25%, respectively, by weight of the resin for 1-5 of the resin).

The properties of the compositions described are presented in table. four.

Claims (1)

Invention Formula A method of preparing a concrete mix by mixing Portland cement, sand, gravel, water and phenol-formaldehyde resin, previously treated with bottom residues of caprolactam production based on caprolactam monomer, in an amount of 15-25% by weight of resin, characterized in that in order to reduce concrete shrinkage and increase its strength, the addition of phenol-formaldehyde resin is further treated with ammonium nitrate in the amount of 15-20% by weight of the resin and crushed together with 18-43% of the total mass of quartz sand to specific 1200-1400 th surface, the resulting additive is introduced into the concrete mixture in an amount E, 15-0,3% by weight of cement. Sand (fine aggregate) 22.4 Crushed stone (large placeholder) 55.3 Phenol-formaldehyde resin, modified by bottom residues (caprolactam (known) Sand Rubble That blitz j 20.3 18,416,414,4 52.4 49,346,243,2 Table3 0.024 0.038 0.052 0.066 20.318.4-16.4 14.4 58,937,355,6 54,1 T a b l and c a 4