The method of obtaining a composite material

 

(57) Abstract:

The invention relates to the construction, and in particular to methods of producing a composite material by hardening of mortar and concrete mixtures. The method includes mixing of the binder and aggregates, fluids and additives with high water-holding capacity, concrete placement and hydration of the concrete. After laying the concrete mix it is kept in air-dry conditions before initial set of concrete strength, then carry out its moisture, and as an additive to use the product cultivation of Bacillus species in sugar-containing aqueous solution. 1 C.p. f-crystals, 1 table.

The invention relates to the construction, namely to methods for composite materials formed during the hardening of concrete, mortar mixes.

A method of obtaining a composite material (1), based on the mixing of the binder and aggregates, the introduction of fluid mixing, the concrete mixture into the form and the hydration of concrete.

However, this is impossible to achieve a high strength because of the high water demand of the concrete mix.

The closest to the invention by the technical sunstitute mixing and additives with high water-holding capacity, the concrete placement and hydration of concrete.

The known method has the following disadvantages. Use as a component of the concrete mix additives with high water-holding capacity (for example plasticizers, superplasticizers) leads to the next. Because immediately after laying the concrete mix shall exercise its moisturizing, which continue as hardening of the concrete, the hydration and hydrolysis of cement used first water introduced into the concrete mix at the time of its preparation and is located either in the pores or adsorbed on the surface of mineral grains binder and filler; in addition, in the hardening concrete water diffuses from the outside when it is wet. As well as in the preparation of concrete mix into it enter water is much more than required to interact with astringent, hydration water held by the additive remains unused, at least in the early stages of hardening. The consequence of this is that the additive molecules occupy a significant amount, and this leads to the fact that the cement stone has a low density and low strength concrete.

The aim of the proposed method is to increase the strength of composition the second material, comprising mixing binder and fillers, the introduction of fluid mixing and additives with high water-holding capacity, the concrete mixture, the moisture of the concrete after placement of concrete mixture it is kept in air-dry conditions before initial set of concrete strength and to dehydration additives with high water-holding capacity, and then carry out its moisture.

After laying the concrete mixture are observed following processes. At the first stage of hardening on the hydration and hydrolysis of the cement consumed water solvate shells, which are formed by free (noderivative molecules additives) water entered when the concrete mix. The temperature rise due to exothermic reactions intensifies the removal of excess (as compared to its required for interaction with the cement) of free water. Due to the increase in temperature and energy of thermal motion of water molecules held by the additive, it is the Department with the surface molecules of the additive and of its internal cavities. This water is used for hydration of the cement. This reduces the volume occupied by the molecules of the additive, increases platnostou hydration and hydrolysis of the binder. The consequence is the reduction of the sizes of the formed crystallites increase in the number of generated crystal intergrowths, which also contributes to increasing the strength of the cement stone. When dehydration occurs molecules of the additive, concrete is gaining initial strength. For its further growth should supply water from the outside. This is ensured by moistening the concrete.

The method is implemented as follows.

Dispense the components of the concrete mix, and then carry out their mixing of injected fluid mixing and additive, continuing stirring; after cooking the resulting mixture was placed in the formwork and kept in air-dry conditions before initial set of concrete strength and to dehydration additives with high water-holding capacity; then the surface of the structure moisturize, providing a constant diffusion of water into the concrete.

The effectiveness of the proposed method, in comparison with the known (prototype), was evaluated on the strength of cement-sand mortar test specimens in compression at 28 days after manufacture. Mortar mix was prepared using Portland cement-300, its consumption was 15 who (height 5 cm, diameter 5 cm) by pressing the cement-sand mixture at a pressure of 0.7 MPa. As an additive used the product of the cultivation of microorganisms of Bacillus species in 5% aqueous solution of molasses for 7 days at 25oC (3).

The additive was injected in the amount of 0,05; 0,20; 0,35; 0.50 and 0.65 per cent solids by weight of cement. After fabrication, the samples were kept in air-dry conditions (temperature 20oC, relative varnosti 60%) for 6, 10, 12, 18 and 24 h; then they stood up to the test under normal conditions (temperature 20oC, relative humidity 100%). Control samples (prototype) immediately after production before the test was kept in normal conditions.

Sample strength in compression was determined on a hydraulic press, model PSA-10 GOST 5802 86. The results are given in the table.

1. The method of obtaining a composite material comprising mixing binder and fillers, the introduction of fluid mixing and additives with high water-holding capacity, the concrete placement, the hydration of concrete, characterized in that after laying the concrete mix it is kept in air-dry conditions before initial set of concrete strength and to dehydration by p. 1, wherein an additive with high water Retentivity use the product cultivation of Bacillus species in sugar-containing aqueous solution.

 

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