Low-autogenous shrinkage and high-performance recycled concrete

Abstract

The invention discloses low-autogenous shrinkage and high-performance recycled concrete which can meet pumping requirements. Each cubic meter of the high-performance recycled concrete contains 400-500kg of a cementing material, 950-1150kg of a coarse aggregate (wherein the substitution rate of the recycled coarse aggregate is 70%-100%), 660-715kg of a natural fine aggregate, 160-180kg of water and 7-9kg of an efficient water-reducing agent, and the high-performance recycled concrete is prepared by a process of enveloping stone with cement. The obtained high-performance recycled concrete has the strength grade of C30-C50 and the slump of 180-220mm, and can effectively improve the autogenous shrinkage performance of the recycled concrete, reduce the total autogenous shrinkage rate by above 25% in comparison with ordinary recycled concrete with the same mixture ratio and enable the total autogenous shrinkage rate to be close to ordinary concrete with the same mixture ratio. The high-performance recycled concrete disclosed by the invention has important theoretical value and social significance in promotion of reasonable and extensive application of the recycled concrete, recovery of construction waste resources and the like.

Description

technical field [0001] The invention belongs to the technical field of civil engineering concrete, and in particular relates to a high-performance recycled concrete with low autogenous shrinkage. Background technique [0002] Since the 21st century, the world economy has developed rapidly as a whole, and the urbanization process has accelerated, so civil engineering has also developed rapidly. Concrete is an important component material of civil engineering, and the social demand for it is also increasing day by day. At present, the annual output of concrete in my country has reached 1.16 billion cubic meters. For such a large output, my country's high-quality natural coarse and fine aggregates have been exhausted. On the other hand, the amount of waste concrete produced every year in countries around the world is quite alarming, including the waste concrete produced by demolition of old building roads, new buildings, concrete factories and prefabricated component factories...

AI Technical Summary

Problems solved by technology

The lower water-binder ratio leads to less free water that can provide cement hydration. The development of early strength makes the free water consumption faster, and the capillary pressure inside the concrete increases. Reduce the inhibition of aggregates on shrinkage, which will lead to a large spontaneous shrinkage of high-performance recycled concrete in the early stage, making the concrete prone to cracks and affecting its strength and durability

Although the current research on high-performance recycled concrete has achieved certain results, it is still in the preliminary stage. The main problem is that there is still a lack of in-depth and systematic research on the volume stability of high-performance recycled concrete autogenous shrinkage.

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