纳米碳酸钙对再生骨料自密实混凝土流变性能及力学性能影响机理OA

This study used nano-calcium carbonate to improve the rheological and mechanical proper-ties of recycled aggregate self-compacting concrete(RASCC).The values of the rheological parameters were accurately determined by rheometer using the concrete equivalent mortar method,the relationship between the rheological parameters and the workability parameters was established,and the enhance-ment mechanism of nano-calcium carbonate on the mechanical properties of RASCC was analyzed by the microscopic performance tests.The results showed that recycled aggregates have an adverse effect on the flowability and mechanical properties of concrete compared to natural aggregates;the content of nano-calcium carbonate at 1.0%reduced the dynamic yield stress and apparent viscosity by 10.0%and 9.5%,respectively.The 28 d compressive strength increased by 5.0%and 9.3%at 0.5%and 1.0%content of nano-calcium carbonate,respectively.It is due to that the nano-calcium carbonate could promote the cement hydration and improve the microstructure of concrete which reduced the porosity.However,too much of it would cause agglomeration and reduced its hydration-promoting effect,the 28 d compressive strength decreased by 2.3%,when the content of nano-calcium carbonate is 1.5%.