Experimental Study On Short-Term Stiffness And Crack Width Of Nano-Silica Concrete Beams

Nano silica is an admixture that combines the advantages of nanomaterials and mineral admixtures.Compared with ordinary concrete,nano silica concrete has the advantages of high strength,high toughness,high durability,etc.However,its current cost is relatively high,and the relevant research time is relatively short,and the research on its influence on the relationship between different mechanical properties of concrete and the performance of components is even rarer.Therefore,it is necessary to conduct experimental research on the relationship between the different mechanical properties of nano-silica concrete and the performance of nano-silica reinforced concrete members.This paper is mainly divided into two experimental parts.In the first part,the cubic compressive strength,split tensile strength and flexural strength of concrete are tested on three different strength grades,three maximum aggregate particle sizes,and whether nano silica is added as variables,and explore the effects of nano-silica on different concretes.The improvement of the interface transition zone and the improvement of the concrete mechanical properties.The test results show that nano-silica has the best effect on improving the strength of concrete with a maximum aggregate particle size of25 mm,and its split-compression ratio and compression ratio have been significantly improved.In the second part,the three-point static loading test of 14 scaled nano-silica concrete beams mainly studied the influence of nano-silica on the bending performance of reinforced concrete beams.The test results show that the influence of nano-silica on the M-? curve of reinforced concrete beams is mainly concentrated in the first and third stages.The cracking load of nano-silica concrete beams is higher,the ductility in the failure stage is better,and the crack width is smaller.Furthermore,through the comparative analysis of the norms of different countries and the theoretical calculation models and test data,it is concluded that the current domestic and foreign norms applied to the design of nano-silica concrete members have no significant difference in ultimate bearing capacity,but in the short-term stiffness and cracks.There is a certain gap in the width prediction,and the calculation accuracy can be improved by revising ? and the stiffness calculation formula.