Lightweight aggregate micro-expansion anti-cracking concrete with adjustable expansion performance

Abstract

The invention relates to lightweight aggregate micro-expansion anti-cracking concrete with adjustable expansion performance, which is prepared by mixing and stirring cement, aggregate, an expanding agent and water according to a mixing ratio with compressive strength of less than 100MPa, part of the aggregate is replaced by the lightweight aggregate with the same volume, the replacement rate is 5-100%, and the expansion performance is adjustable. The expanding agent comprises at least one of a calcium sulphoaluminate expanding agent, a calcium oxide expanding agent and a magnesium oxide expanding agent. The method has the advantages that the internal tensile stress caused by the coupling effect of temperature shrinkage, autogenous shrinkage and drying shrinkage in the concrete is effectively reduced, so that the generated crack can be effectively controlled, the maximum width of the crack appearing in the concrete is reduced, the crack gap is reduced, and the number of the crack is reduced. The novel magnesium oxide expanding agent is added to adjust the expansion performance under different working conditions, and has a sufficient compensation effect on drying shrinkage besides autogenous shrinkage and temperature shrinkage. Therefore, the engineering practical effect and the economic benefit are optimized.

Description

technical field [0001] The invention relates to the technical field of building materials, in particular to a lightweight aggregate micro-expansion crack-resistant concrete with adjustable expansion performance. Background technique [0002] The problem of cracking in concrete is the autogenous shrinkage caused by the reaction of hydration products, the temperature shrinkage caused by the temperature drop after the temperature of the concrete rises due to the hydration reaction process, and the drying shrinkage caused by the evaporation of water inside the concrete during long-term use. , caused by the coupling of the three. [0003] Temperature deformation is the volume expansion caused by exothermic heating during the cement hydration reaction and the volume shrinkage caused by subsequent heat loss and cooling. In particular, for large-scale concrete structures with large cross-sectional areas, and concrete structures with a large amount of cement per unit volume although...

AI Technical Summary

Problems solved by technology

However, this proportioning scheme does not systematically design the expansion required for different actual engineering conditions (such as different temperature histories, constraints, and curing conditions), resulting in a low controllability of the expansion performance and no benefits in use and Optimized in terms of economic cost

Moreover, since the expansion of the calcium sulfoaluminate (or calcium oxide) expansion agent is basically completed in the early stage (mainly within a week), it cannot effectively compensate for the drying shrinkage of the concrete structure under long-term use.

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