Influence Of Coarse Aggregate On Concrete Mixing Process Nnder Different Mixing Methods

Concrete is the largest building material in the world,and is widely used in highways,bridges,dams,tall buildings and other buildings.The strength and durability of concrete will directly affect the safety and service life of these buildings.The mixing uniformity of concrete is an evaluation index for evaluating the strength and durability of hardened concrete.Therefore,a large number of experts and scholars have studied the mixing uniformity of concrete.Some studies have found that coarse aggregates play a positive role in the mixing uniformity of concrete during the mixing of concrete.Therefore,this paper mainly studies the effect of coarse aggregate on the concrete mixing process under different mixing methods,which is instructive for the rational use of concrete mixing methods and mixing processes.This paper compares the mixing uniformity of mortar and cement concrete to study the effect of coarse aggregate on the mixing process of concrete under different mixing methods.This test is divided into two parts: mortar test and concrete test.By comparing and analyzing the rheology and compressive strength of the mortar and the microstructure of the hardened mortar under different mixing methods,the effects of vibration stirring and high-speed mixing on the mortar mixing uniformity were studied during the mortar mixing process without coarse aggregates.In this paper,the concrete test adopts the step-by-step feeding method,and the concrete mixing is divided into two processes-mortar mixing and concrete mixing.By analyzing the mixing power curve in the mixing process of cement concrete,comparing the power ratio of "characteristic point" and the mixing time from "viscosity point" to "flow point" of mortar and concrete mixing,the effect of coarse aggregate on the uniformity of concrete mixing was studied;Vibration and high-speed mixing were applied in the mortar mixing process and the concrete mixing process respectively.The rheological properties,compressive strength and microstructure of the concrete were analyzed to study the mixing of aggregates with different particle sizes under vibration and high-speed mixing The impact of the process.By analyzing the rheological properties,compressive strength and microstructure of mortar and concrete under vibration mixing,the optimal aggregate particle size for vibration during concrete mixing was studied.The test results show that in the mortar mixing process without coarse aggregates,vibration mixing can improve the uniformity of mortar mixing,but the effect is not obvious.However,high-speed mixing can greatly improve the uniformity of mortar mixing.The apparent density is about 9% higher than other stirring methods,and the 28 d intensity is about 65% higher.Therefore,in the mixing process of mortar,the influence of speed is much greater than that of vibration;in the process of concrete mixing with coarse aggregate,vibration mixing has a significant effect on the uniformity of concrete mixing,which is greater than the effect of speed.The strength of 7d is about 5.25% higher than that of other mixing methods,and the strength of 28 d is about 3.48% higher.Comparing the microstructure of hardened mortar and hardened concrete,it is known that coarse aggregate has a positive effect on the mixing uniformity of cement slurry.