Experimental Study On Modification Of Shale Ceramsite Lightweight Aggregate Concrete

Lightweight aggregate concrete has always been one of the important development directions of concrete materials due to its characteristics of small bulk density,good heat insulation and excellent earthquake resistance.It has significant advantages in the fields of long-span Bridges,high-rise buildings and super high-rise buildings.However,its defects of "high strength,high brittleness" and "poor freezing resistance" restrict its further popularization and application in building structural engineering.Polypropylene fiber has the effect of "bridge toughening",which can significantly enhance the toughness of concrete;The silica powder has the effect of "packing compactness",which can obviously improve the compactness of concrete structure.The influence of polypropylene fiber and silica powder on the performance of lightweight aggregate concrete is studied,and the reasonable mixing range of polypropylene fiber and silica powder is further defined,which provides certain reference significance for practical engineering application.The following studies were carried out in this paper:(1)polypropylene fiber was added into lightweight aggregate concrete,and the influence law of concrete performance with its dosage was experimentally studied,and the range of its excellent modified dosage was determined.(2)Add silica powder with equal mass instead of cement into lightweight aggregate concrete,test study the influence law of concrete performance with its dosage,and determine the excellent dosage range of silica powder modified.(3)In terms of mechanical properties,the complementary effect of polypropylene fiber and silica powder on the performance modification of concrete is used to try to mix them into lightweight aggregate concrete,study the influence law of concrete performance with the change of the mixture amount of polypropylene fiber and silica powder,and explore the blending range of the excellent composite modification of the two.The following conclusions were reached:(1)With the increase of polypropylene fiber content,the compressive and flexural strength of lightweight aggregate concrete increases first and then decreases.At the same time,the frost resistance increased first and then decreased.When the content of polypropylene fiber is 0.4kg/m ~3 ～1.12kg/m ~3,the modification effect of polypropylene fiber on the flexural strength,compressive strength and frost resistance of shale ceramsite lightweight aggregate concrete is better than that of the reference group.(2)With the increase of silica powder content,the compressive and flexural strength of lightweight aggregate concrete increases first and then decreases.At the same time,the frost resistance increased first and then decreased.When the silica powder mixture ratio is2%～7%,the modification effect of silica powder on the compressive strength,flexural strength and frost resistance of shale ceramide lightweight aggregate concrete is better than that of the reference group.(3)By utilizing the complementary effect of polypropylene fiber and silicon powder on the mechanical properties of concrete,an attempt is made to mix the two into lightweight aggregate concrete,and the influence of the changes in concrete properties with the addition of the two is studied to explore the optimal range of their combined modification...