Effect of calcined nano-attapulgite on frost resistance of recycled concrete
In order to comprehensively utilize solid wastes,NA is replaced by RA with a replacement rate of 30％,and cement(0％,2％,4％,6％,8％)is replaced by calcined NAT to make NRC.Freeze-thaw cycle tests are carried out to explore the influence of NAT on the freezing resistance of NRC.Scanning electron microscopy and nitrogen adsorption are used to study the microstructure of NRC.The results show that with the increase of freeze-thaw cycles,the mass loss rate of NRC present a negative growth first and then a positive growth.Under the same number of freeze-thaw cycles,the relative dynamic elastic modulus of NRC is the maximum when the NAT content is 6％.The C-S-H gel is generated by secondary hydration reaction after NAT incorporation under adaptive dosage,which improves the compactness inside the mortar and between the mortar and aggregate,fills the pores in the inner part of NRC,improves the strength of interfacial transition zone,optimizes the internal pore structure,and improves the frost resistance of RC.
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