Low-air-shrinkage anti-crack concrete

Abstract

The invention discloses low-air-shrinkage anti-crack concrete. The low-air-shrinkage anti-crack concrete is prepared from, by weight, 320-380 of cement, 50-100 parts of rice hull ash, 30-60 parts of carborundum powder, 620-720 parts of machine-made sand, 60-100 parts of carborundum, 1000-1090 parts of rubble, 8-12 parts of shrinkage reducing agent, 5-7 parts of water reducing agent and 120-200 parts of water. The strength grade of the low-air-shrinkage anti-crack concrete is C50-C60, 7d air shrinkage value is 70-100*10-6, 28d air shrinkage value is 180-250*10-6, 90d air shrinkage value is 240-300*10-6, the values tend to be stable, and early anti-cracking capability grade is L-V. Rice hull ash, shrinkage reducing agent, carborundum powder and carborundum in the concrete are all good for reduction of air shrinkage, so that anti-cracking ability is improved, a super-compound effect can be generated through mixing, and air shrinkage and cracking sensitivity of the concrete is reduced greatly; the air shrinkage change of the concrete can be effectively adjusted and the anti-crack property of the concrete can be improved by controlling the mass ratio of the components of the concrete.

Description

Technical field: [0001] The invention belongs to the field of building materials, and in particular relates to a low-shrinkage anti-crack concrete. Background technique: [0002] Concrete shrinkage refers to the phenomenon that after the concrete is hardened, as the surface moisture gradually evaporates, the internal relative humidity gradually decreases, which causes the volume of concrete to decrease. In actual engineering, the cracks caused by shrinkage of concrete are the most common. Among the many types of concrete shrinkage, dry shrinkage is one of the most important reasons for concrete cracking. The water loss of the concrete surface is fast, and the internal water loss is slow, so the uneven shrinkage of the concrete surface is large, and the internal shrinkage is small. Cracks occur when the tensile strength of concrete is exceeded. Generally speaking, in actual engineering, high dry shrinkage value of concrete corresponds to a greater risk of cracking. Therefor...

AI Technical Summary

Problems solved by technology

At present, the preparation of high-strength concrete usually uses non-P·I cement mixed with various mixed materials with unknown components and dosages. Some of the mixed materials are not conducive to reducing the concrete’s drying shrinkage and cracking sensitivity. At the same time Adding a certain amount of mineral admixtures makes the type and amount of concrete components unknown, and it is impossible to scientifically and effectively determine the concrete mix ratio that is beneficial to reduce dry shrinkage and crack sensitivity

In addition, due to the high strength level of concrete, its water-binder ratio is relatively low, so that some cementitious materials have not been hydrated.

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