PCCP外层防护用复合材料的力学性能研究

Research on mechanical properties of composite materials for PCCP outer layer protection

基于预应力钢筒混凝土管(PCCP)外层防护水泥砂浆受拉易裂的问题及消纳大宗工业固废和降低水泥碳排放的目的,以赤泥、粉煤灰和矿渣全取代水泥,制备得到了满足低碳及拉伸变形需求的全固废基高延性地质聚合物复合材料(High Ductility Geopolymer Composites,HDGC)。通过改变前驱体相对含量,探究了HDGC的宏观和细观力学性能、微观形貌及应变硬化能力。结果表明:HDGC的抗压强度随赤泥掺量的增加而减小,随矿渣掺量的增加而增强,但抗拉强度与弯曲强度随矿渣掺量的增加先增大再减小;矿渣掺量为20%的HDGC抗压强度不低于45 MPa,抗拉强度与拉伸应变分别大于4 MPa和4%;HDGC细观力学参数均随矿渣掺量的增加而增大,其强度指数和能量指数高于推荐阈值,拉伸应变硬化能力显著。

In addressing the issue of the cracking susceptibility of cement mortar in the outer layer of prestressed steel cylindrical concrete pipes(PCCP),and with the goal of utilizing bulk industrial solid waste and reducing cement carbon emissions,the High Ductility Geopolymer Composites(HDGC)based on solid waste was prepared by replacing cement with red mud,fly ash,and slag to meet the requirements of low-carbon and tensile deformation.The mechanical properties,microscopic morphology,and strain-hardening capacity of HDGC were investigated by varying the relative content of precursors.The results show that the compressive strength of HDGC decreases with the increase of red mud content and enhances with the increase of slag content,but the tensile strength and bending strength first increase and then decrease with the increase of slag content.The compressive strength of HDGC with 20%slag content exceeds 45 MPa,whose tensile strength and strains exceed 4 MPa and 4%respectively.The micro mechanical parameters of HDGC increase with the increase of slag content,and their strength index and energy index are higher than the recommended threshold,and the tensile strain hardening ability is significant.