RU2331600C1 - Method for manufacturing aggregate for concrete - Google Patents

Abstract

FIELD: building and construction.

SUBSTANCE: method for producing aggregate includes covering surface of porous chip with at least two layers of water-cement paste with the subsequent hardening of the said layers. Water cement applied for the said layers is made on the basis of different kinds of cement varying in physical and chemical characteristics, water cement applied for the last layer being made on the basis of waterproof high-expansion cement.

EFFECT: increased waterproof capacity of aggregate.

2 ex

Description

The invention relates to the production of aggregates for special types of heavy concrete (hydraulic, road, etc.).

A known method of manufacturing aggregate for concrete, comprising applying to the surface of the grains of aggregate, at least one layer of cement paste with its subsequent curing [1].

A known method of manufacturing aggregate for concrete, comprising applying to the surface of the grains of aggregate, at least two layers of cement paste with their subsequent curing [2]. The aggregate obtained in this way has a reduced bulk density, however, it is not protected from aggressive media (water, solutions of acids, salts, alkalis, temperature, etc.), which reduces its technical and operational characteristics.

The objective of the invention is to increase the water resistance of the aggregate at a pressure of up to 0.6 MPa.

The technical result is achieved by the fact that in the method of manufacturing aggregate for concrete, comprising applying to the surface of the grains of porous gravel, at least two layers of cement dough with their subsequent curing, for applying the layers use a cement dough based on cements that differ in their physical -chemical properties, each layer after its application is cured, and for the last layer as a cement paste use cement paste, prepared on the basis of waterproof expansion axis of cement.

Waterproof expanding cement has a composition, wt.%: Alumina cement 70-76%, semi-aquatic gypsum 20-22%, calcium hydroaluminate 10-11%. As porous crushed stone, agloporite crushed stone, crushed stone obtained by crushing volcanic rocks, etc. can be used.

The method is illustrated by the following examples.

1. Prepare a cement paste of the composition, wt.%: Portland cement 60.0; water - 40.0. The grains of the porous aggregate (crushed stone) preliminarily cleaned of impurities are immersed in a container with cement paste. The consumption of cement paste is 0.2 kg per 1 kg of crushed stone. After enveloping the grains, the aggregate is removed from the container and laid in one layer, for example, on a grid. After the curing of the first layer of cement dough on grains of crushed stone, the operation is repeated using a cement dough of the following composition, wt.%: Waterproof expanding cement 60,0; water - 40.0. As a result, a two-layer coating forms on crushed grains, while the aggregate has a reduced (by 7–9%) bulk density and increased water resistance at pressures up to 0.6 MPa.

2. Prepare a cement paste of the composition, wt.%: Portland cement 60.0; water - 40.0. The grains of the porous aggregate (crushed stone) preliminarily cleaned of impurities are immersed in a container with cement paste. The consumption of cement paste is 0.2 kg per 1 kg of crushed stone. After enveloping the grains, the aggregate is removed from the container and laid in one layer, for example on a grid. After the curing of the first layer of cement paste on crushed grains is completed, the operation is repeated using a cement paste of the following composition, wt.%: Sulfate-resistant Portland cement 60.0; water - 40.0. After enveloping the grains, the aggregate is removed from the container and laid in one layer. After the curing of the second layer of cement dough on crushed grains is completed, the operation is repeated using a cement dough of the following composition, wt.%: Waterproof expanding Portland cement 60.0; water - 40.0. After enveloping the grains, the aggregate is removed from the container and laid in one layer, a three-layer coating is formed on the grains of crushed stone, while the aggregate has a reduced (by 11-13%) bulk density, increased water resistance at a pressure of up to 0.6 MPa and resistance to mineralized water .

The method allows to obtain aggregate for concrete with improved technical and operational characteristics.

Information sources

1. SU No. 1028634.

2. GB No. 2,327,669.

Claims (1)

A method of manufacturing aggregate for concrete, including applying at least two layers of cement paste to the surface of grains of porous gravel, followed by their hardening, characterized in that the cement paste, prepared on the basis of cements differing in their physicochemical properties, is used for applying the layers , each layer after its application is cured, and for the last layer as a cement paste use cement paste, prepared on the basis of waterproof expanding cement.