碱激活法制备轻质牡蛎壳基地质聚合物的结构与性能

Structure and Properties of Lightweight Oyster Shell-based Geopolymers Prepared with Alkali Activation Method

我国沿海地区牡蛎养殖每年产生大量牡蛎壳,其资源化利用关系到环境保护与产业可持续发展。以牡蛎壳和粉煤灰为主要原料,以NaOH溶液和水玻璃为碱激活剂,以H_(2)O_(2)为发泡剂,制备牡蛎壳基轻质(多孔)地质聚合物。利用XRD、FTIR、SEM、接触角测试仪等技术手段,分析气孔结构和显微组织,系统研究发泡剂、硅酸铝纤维和硬脂酸钙对地质聚合物的气孔结构、表观密度、抗压强度和风化性能的影响。研究结果表明,随着H_(2)O_(2)添加量的提高,地质聚合物的表观密度和抗压强度持续降低,但比强度先增大后减小;随着硅酸铝纤维添加量增大,地质聚合物的表观密度、抗压强度和比强度均先增大后减小,当添加量为1.00%时达到最大值,分别为0.63g·cm^(-3)、4.45MPa和6.98 kN·m·kg^(-1)。添加少量硬脂酸钙不仅不影响地质聚合物的结构和抗压强度,还能显著改善其风化性能,当添加量为0.50%时达到最佳,失重率和比强度损失分别为10.1%和14.1%。这种轻质地质聚合物有望用于人行道砖和路缘石,实现牡蛎壳的资源化增值利用。

The oyster cultivation in coastal areas of China produces a large number of oyster shells every year,whose resource utilization is related to environmental protection and sustainable development of industry.Lightweight oyster shell-based geopolymers were prepared by using oyster shell and fly ash as main raw materials,water glass and NaOH solution as composite activators,and H_(2)O_(2) as the foaming agent.The effects of foaming agent,aluminum silicate fiber and calcium stearate on pore structure,apparent density,compressive strength and weathering properties of the oyster shell geopolymers were systematically studied.The pore structure and microstructure were analyzed by using XRD,FTIR,SEM and contact angle tester.It is found that apparent density and compressive strength of the geopolymer continue to decrease with increasing content of H_(2)O_(2),but the strength increases first and then decreases.Apparent density,compressive strength and specific strength of the geopolymers increase first and then decrease with increasing content of aluminum silicate fiber,reaching the maximum values at 1.00%,which are 0.63 g·cm^(-3)3,4.45 MPa and 6.98kN·m·kg^(-1),respectively.The addition of a small content of calcium stearate did not affect structure and compressive strength of the geopolymers,the weathering performance was significantly improved.When the content was 0.50%,the optimal weight loss and specific strength loss were 10.1%and 14.1%,respectively.This lightweight geopolymer is expected to be useful in sidewalk bricks and curb stones to realize the value-added utilization of oyster shells as resources.