Experimental Research On The Factors Influencing The Autogenous Shrinkage Performance Of High-Performance Recycled Concrete

With the development of social economy, huge concrete production made resource, energy, environment and related social problems even more prominent. Sustainable development and environmental protection strategy is urgently needed to make effective and rational use of waste concrete, recycled concrete arises at the historic moment. Study of recycled concrete at home and abroad in recent years has been some progress, but there are still many problems. In view of this, this paper focuses on the research of the high-performance recycled concrete and its influence factors on autogenous shrinkage. Main work and conclusions are as follows.1. Through the study of the basic properties of the coarse aggregate, analyses the difference of recycled coarse aggregate and natural aggregate. The experimental results show that the performance of recycled coarse aggregate is worse than natural aggregate, embodied in aggregate coarser, lower apparent density and bulk density, larger porosity, higher water absorption and crushing index.2. Reference to the high-performance way of normal concrete, in concrete workability for standard, control the slump in 180-220 mm, and use paste wrapped stone secondary mixing method to product C30 strength grade of high-performance recycled concrete. Test results show that the performance of concrete deterioration with the recycled coarse aggregate, mixing only with fly ash and compound mixing with fly ash and slag make the performance of concrete better.3. By the research on basic mechanical properties of the high-performance recycled concrete, taking the influence of recycled coarse aggregate, different mixing amount of fly ash and different mixing amount of fly ash and slag to the basic mechanical properties of the high-performance recycled concrete. Test results show that the join of recycled coarse aggregate make concrete cube compressive strength and elastic modulus decrease. As the mixing amount of fly ash, fly ash and slag increasing, the concrete mechanics performance degradation, but mixing fly ash and slag make concrete mechanics performance degradation degree smaller.4. Taking the influence of recycled coarse aggregate, different mixing amount of fly ash and different mixing amount of fly ash and slag to the autogenous shrinkage of the high-performance recycled concrete through the experiment, analysis of high performance recycled concrete and ordinary concrete, high performance concrete, self-compacting concrete difference in the autogenous shrinkage. The test results show that the recycled coarse aggregate is against control the autogenous shrinkage, single mixing fly ash can effectively control the autogenous shrinkage, compared with single mixing fly ash, double mixing fly ash and slag are more conducive to controlling autogenous shrinkage, the high-performance recycled concrete autogenous shrinkage development law with ordinary concrete, high performance concrete, self-compacting concrete consistency, but it have larger autogenous shrinkage values.5. Analyzing and comparing several commonly used autogenous shrinkage calculation model with experimental values of this paper, selecting a more appropriate one as reference. Inheriting the original autogenous shrinkage model of research group, combined with the autogenous shrinkage test results to adjust parameters, then a suitable autogenous shrinkage calculation model for high-performance recycled concrete is put forward.