Flexural Behaviour Of Alkali-activated Slag-fly Ash Concrete Beams

Alkali activated concrete is a green concrete made of industrial waste,which can effectively reduce the emission of carbon dioxide and realize the recycling of industrial waste.The performance of alkali activated concrete is related to mineral raw materials,activators,mix proportion and curing conditions.The alkali activated concrete based on performance requirements requires that the alkali activated concrete has better performance in workability,compressive strength and durability.In this paper,slag and fly ash are used to prepare alkali activated concrete based on performance requirements,and the flexural behavior of the beam components of the concrete is studied,and the following research results are obtained:(1)The moment curvature relationship,short-term bending stiffness,bearing capacity of each stage,ductility,load strain relationship,crack development and failure mode of alkali activated concrete beams are studied.The results show that the bending performance indexes of alkali activated concrete beams are basically consistent with those of ordinary concrete beams,and alkali activated concrete beams are basically consistent.The bending capacity of the beam in each stage is higher than that of the ordinary concrete beam.(2)The effects of concrete strength,longitudina l tensile reinforcement ratio and beam depth on the moment curvature relationship,short-term bending stiffness,bearing capacity,ductility,crack development and failure mode of alkali activated concrete beams are discussed.The results show that the inc rease of concrete strength from C30 to C70 has little effect on the flexural indexes;with the increase of reinforcement ratio,the flexural capacity of alkali activated concrete beams at different stages will be significantly increased,while the ductilit y will be significantly reduced;while with the increase of beam depth,the bending stiffness and bearing capacity of alkali activated concrete beams will be significantly increased,and the increase of ductility will be decreased with the increase of concrete strength.(3)The theoretical analysis of the alkali activated concrete beams under various test conditions is carried out by using the formula recommended by the existing code.The comparison between the test results and the theoretical calculation value s shows that: for the cracking bearing capacity,the theoretical value and the test value of the code are relatively discrete;for the normal service limit state of the components,the formula prediction value corresponding to the crack width limit value i s conservative;for the yield bearing capacity and the ultimate bearing capacity calculated by the current code is in good agreement with the test results.(4)By using ABAQUS software,the nonlinear simulation analysis of alkali activated concrete beam is carried out,the correctness of the constitutive relation of alkali activated concrete is verified,and the working mechanism of alkali activated concrete beam is revealed.