RU2425813C1 - High-strength concrete - Google Patents

Abstract

FIELD: construction. ^ SUBSTANCE: high-strength concrete is made of a mixture of raw materials, which contains portland cement, sand, crushed stone, water and a complex additive represented by ferric hydroxide sol (III) with density of 1.021 g/cm3, hydrogen index of 4.5-5.5 and microsilica, at the following ratio of additive components, in wt %: 45.50-46.00 and 54.00-54.50, accordingly, at the following ratio of raw materials mixture components, wt %: portland cement 20.60-27.40, sand 21.80-24.70, crushed stone 42.40-44.50, the specified additive 0.70-0.90, water 7.70-9.30. ^ EFFECT: increased density of concrete, reduced water absorption. ^ 9 dwg, 1 tbl

Description

The invention relates to building materials and can be used for the manufacture of concrete products in civil and industrial construction, monolithic construction, in concreting densely reinforced structures, as well as in the construction of structures for special purposes.

A known raw material mixture for the manufacture of high-strength concrete (Yu.M. Bazhenov. Concrete technology. Publishing House of the Association of Building Universities (DIA), Moscow, 2002, p. 377), containing Portland cement, silica-containing component, sand, gravel, silicate flour, additive and water.

The disadvantage of this technical solution is the limited density value.

A known raw material mixture for the manufacture of high-strength concrete (RU No. 2256629, C04B 28/04, published July 20, 2005), comprising: Portland cement, sand, gravel, a silica-containing component represented by orthosilicic acid sol with a density of 1.014 g / cm ³ , hydrogen indicator 5-6, the addition of "DEYA-M" and water.

The disadvantage of this technical solution is the limited density value.

The closest in technical essence to the claimed invention is high-strength concrete (RU No. 2323910, C04B 28/04, 22/06, 111/20, publ. 05/10/2008), containing: Portland cement, sand, gravel, additive - hydroxide sol iron (III) with a density of 1.018 g / cm ³ , a hydrogen index of 4.5-5.5 and water in the following ratio of components, wt.%:

Portland cement 23.6-26.9 Sand 23.7-25.2 Crushed stone 36.8-38.4 Sol of iron (III) hydroxide with a density of 1.018, pH 4.5-5.5 0.7-0.76 Water 11.9-12.04

The disadvantage of this technical solution is the limited density value.

The problem to which the invention is directed, is the creation of high-strength concrete with a higher density value and a lower value of water absorption.

The technical result is achieved by the fact that in high-strength concrete, obtained from a mixture containing Portland cement, sand, gravel, additive and water, the additive is complex and consists of iron hydroxide sol (III) with a density of 1.021 g / cm ³ , a hydrogen index of 4.5 -5.5 and silica fume, in the following ratio of components, wt.%:

Iron (III) hydroxide sol

density 1,021 g / cm ³ , pH 4.5-5.5 45.50-46.00 Silica fume 54.00-54.50

in the following ratio of components of the raw mix, wt%:

Portland cement 20.60-27.40 Sand 21.80-24.70 Crushed stone 42.40-44.50 Specified Additive 0.70-0.90 Water 7.70-9.30

Long-life high-strength concrete should be relatively impervious to external influences. Penetration of liquid substances of varying degrees of aggressiveness into concrete is determined by the permeability of concrete, which is one of its important characteristics.

In reinforced concrete, the penetration of moisture and air causes corrosion of the reinforcement, which increases in volume and, as a result, leads to cracking and destruction of the protective layer of the concrete structure.

The movement of water through the thickness of concrete is determined not only by the movement of water, but also by the moisture gradient on opposite surfaces of the concrete, i.e. osmotic effect.

In the presence of said complex additive, the density of activated cement stone increases.

Calorimetric studies of the hardening system were carried out for a control system consisting of Portland cement ПЦ400 Д20 of Pikalevsky cement JSC and an activated cement system. As an activator, a complex additive was used - a sol of iron (III) hydroxide in combination with silica fume, with a colloidal particle.

The data of calorimetric studies are presented in figures 1-9.

Figure 1 shows the kinetics of heat during the hydration of cement without using the proposed additives (control concrete) for 1 hour.

Figure 2 shows the kinetics of heat dissipation of the prototype for 1 hour.

Figure 3 shows the kinetics of heat during cement hydration in the developed concrete with the specified complex additive for 1 hour.

Figure 4-6 is a continuation of figure 1-3 for a period of time from 1 hour to 75 hours.

Figure 1-6: W (t) - heat flow rate, mW / h; t is the time, h or min.

The data of the calorimetric studies presented in figures 1-6 show that the heat release rate in the system of "Portland cement- (sol-additive)" (figures 3 and 6), as well as in the case of pure Portland cement (figures 1 and 4 ) has two thermal effects. The difference is that the first thermal effect in activated concrete (Fig. 3) is accompanied by a large heat release per unit of production in the same period of time equal to 30 minutes (Figs. 1-3). This is due to the large involvement of tricalcium aluminate (Portland cement mineral) in the hydration process.

The second thermal effect (Figs. 4-6), which, as a rule, is caused by the hydration of tricalcium silicate, in activated concrete (Fig. 6) begins 2 hours 20 minutes earlier than in the control non-additive composition (Fig. 4). This is due to an increase in the rate of interaction of the main mineral of Portland cement, namely, tricalcium silicate with water in the presence of this complex sol-containing additive.

The total heat during the hydration of cement in the process of obtaining concrete is shown in Fig.7-9.

Figure 7 shows the total heat during the hydration of cement in the process of obtaining control concrete.

On Fig shows the total heat during cement hydration in the process of obtaining the prototype.

Figure 9 shows the total heat during cement hydration in the process of obtaining developed concrete with the specified complex additive.

In Fig.7-9: Q - total heat loss, J / g; t - time, h

The total heat loss at the age of 3 days for activated concrete is 48.1% higher and amounts to 158.0 J / g (Fig. 9) relative to the total amount of heat equal to 106.7 J / g (Fig. 7), control (non-additive) concrete. Therefore, this complex additive has an activating effect on concrete production, that is, the amount of Portland cement minerals reacting with water increases, and the beginning of this interaction in the presence of this complex additive is increased and accelerated.

The use of this complex sol-containing additive provides an increase in the density of concrete and compaction of its structure.

The density of concrete, as a characteristic of its permeability, was determined by the parameter of water absorption, which was evaluated in accordance with GOST 12730.3-78 on samples 10 × 10 × 10 cm in size. The results are presented in the table.

At the filing date, according to the applicant, the claimed high-strength concrete is not known and this technical solution has world novelty.

The claimed combination of essential features exhibits a new property in the presence of an iron (III) hydroxide sol with a density of 1.021 g / cm ³ and a hydrogen index of 4.5-5.5 and silica fume, namely, it increases the density of concrete, which results in a decrease in concrete water absorption.

The mixture, including Portland cement, sand, gravel and the proposed complex additive, ensured the production of high-strength concrete characterized by increased density, estimated by the value of water absorption at the design age (28 days) of activated concrete, which decreases by 11% and amounts to 1.9% compared with the prototype.

According to the applicant, the claimed invention meets the eligibility criteria - inventive step.

The claimed invention is industrially applicable and can be used in civil and industrial construction, monolithic construction, in concreting densely reinforced structures, as well as in the construction of structures for special purposes.

The raw mix is prepared as follows: 3-4 drops of a saturated solution of iron chloride are added to 100 cm of boiling water. In this case, hydrolysis of iron chloride proceeds vigorously and the appearing molecules of iron hydroxide condense into colloidal particles. The resulting sol of iron hydroxide has a cherry-brown color. Thus, a sol of iron hydroxide (III) is obtained with a density of 1.021 g / cm ³ , a hydrogen index of 4.5-5.5, which is a cherry-brown liquid.

The dosed sol of iron (III) hydroxide and silica fume (white soot BS-50; GOST 18307-78 *) are placed in dosed water. Dispersed components of the raw material mixture: Portland cement M400 D20, sand with a particle size module of 2.1, crushed stone fractions of 5-10 mm and water containing a dosed complex additive are placed in a concrete mixer, where the components are mixed, and the concrete mixture is prepared from which the required concrete products are made and samples for quality control by density parameters by water absorption.

Concrete hardening was carried out under normal conditions and the test results, according to GOST 12730.3-78, are presented in the table.

Analysis of the data presented in the table shows that the density of the proposed high-strength concrete according to this invention increases due to a decrease in its porosity, this can be seen from the value of water absorption at the design age (28 days) of activated concrete, which decreases by 11% and amounts to 1.9 % compared with the prototype.

Claims (1)

High-strength concrete obtained from a raw material mixture containing Portland cement, sand, gravel, additive and water, characterized in that the additive is complex and consists of iron hydroxide sol (III) with a density of 1.021 g / cm ³ , a hydrogen index of 4.5-5 , 5 and silica fume in the following ratio of components, wt.%:
Iron (III) hydroxide sol a density of 1.021 g / cm ³ pH 4.5-5.5 45.50-46.00 Silica fume 54.00-54.50
in the following ratio of components of the raw mix, wt.%:
Portland cement 20.60-27.40 Sand 21.80-24.70 Crushed stone 42.40-44.50 Specified Additive 0.70-0.90 Water 7.70-9.30

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