Effect of Rice Husk Ash and Silica Fume on Mechanical Properties of Cement Mortar under Freeze-Thaw Cycles
To study the effects of rice husk ash(RHA)and silica fume(SF)on the compressive strength,energy,and pore changes of cement mortar under freeze-thaw cycles,uniaxial compression tests were conducted on cement mortars with different replacement ratios of RHA and SF after 0,5,15,and 30 freeze-thaw cycles.The results indicated that the stress-strain curves of the specimens underwent four stages:compaction stage,elastic deformation stage,crack propagation stage,and failure stage.As the curing age increased,the compressive strength of the specimens gradually increased.With the increase in the replacement ratio of RHA,the compressive strength,elastic modulus,absorbed energy,and elastic energy of the specimens initially increased and then decreased,while the deterioration degree and the number of pores initially decreased and then increased.As the number of freeze-thaw cycles increased,the compressive strength,elastic modulus,absorbed energy,elastic energy,and dissipated energy of the specimens gradually decreased,and the deterioration degree and pore quantity increased.When the replacement ratio of RHA to SF reached 50%,the mechanical properties and frost resistance of the specimens were optimal.
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