Research on early mechanical and hydration characteristics of sprayed concrete
The bonding strength of sprayed concrete currently used is relatively low,and it cannot meet the requirements for support strength in the initial stage after construction.Therefore,it explores the mechanical properties and hydration heat reaction characteristics of different composite cementitious materials by introducing silica fume,ceosphere,cellulose,and accelerator.Based on the Krstulovic-Dabic hydration kinetics model,the hydration process of composite cementitious materials was studied.The mechanical development law of the combined sprayed concrete was analyzed through the early age compressive strength and splitting strength.The results show that silica fume and accelerator have a significant effect on improving the early mechanical strength of concrete,while cellulose and ceosphere have a reducing effect on the strength.The hydration kinetics process of the composite cementitious system under various operating conditions consists of three stages,crystallization nucleation and crystal growth(NG),phase boundary reaction(I)and diffusion(D).The increase of silica fume content will increase the height of the dissolution peak by 20.4%and the occurrence time of the early reaction peak by 22.2%.The addition of cellulose significantly increased the dissolution peak intensity but reduced the reaction peak height.
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