磷石膏掺量对PG-CS-SS-SL复合胶凝材料关键性能的影响

Effect of phosphogypsum dosage amount on key properties of PG⁃CS⁃SS⁃SL composite cementitious materials

为提高工业固体废弃物在辅助胶凝材料中的利用,以工业固体废弃物磷石膏(PG)、电石渣(CS)、钢渣(SS)和矿渣(SL)为原材料制备磷石膏-电石渣-钢渣-矿渣复合胶凝材料(PG-CS-SS-SL)。研究了PG掺量对PG-CS-SS-SL流动度、强度特性、吸水率、软化系数和微观结构的影响。使用XRD、FT-IR、TG-DTG和SEM对PG-CS-SS-SL强度形成机理和性能发生变化的原因进行分析。结果表明,PG-CS-SS-SL的流动度随PG掺量的增加而增大;PG-CS-SS-SL的强度和软化系数均随PG掺量的增加而呈现出先略微增加后降低的趋势,当PG掺量为10%时PG-CS-SS-SL的28 d强度最高,其抗折和抗压强度分别为6.8 MPa和32.9 MPa,相应的耐水性能最优,其软化系数为0.904;PG-CS-SS-SL的吸水率随PG掺量的增加呈现出先略微降低后增加的趋势,当PG掺量为10%时PG-CS-SS-SL的吸水率最小。微观分析表明,适量的PG能够促进PG-CS-SSSL体系中C-(A)-S-H凝胶和AFt的形成,优化硬化浆体的微观结构,有利于硬化浆体的强度发展;但掺量过多会导致硬化浆体的微观结构变差,造成PG-CS-SS-SL性能变差。

In order to improve the utilization of industrial solid wastes in auxiliary cementitious materials,phosphogypsum(PG),carbide slag(CS),steel slag(SS)and mining slag(SL)are used as feedstocks to prepare composite cementitious materials(PG⁃CS⁃SS⁃SL).The influences of PG dosage on the flowability,strength properties,water absorbing rate,softening coefficient and microstructure of PG⁃CS⁃SS⁃SL are studied.The strength formation mechanism of PG⁃CS⁃SS⁃SL and the reasons for the changes in its properties are analyzed by means of XRD,FT⁃IR,TG⁃DTG,and SEM.Results show that the flowability of PG⁃CS⁃SS⁃SL increases with the increase of PG dosage.Both strength and softening coefficient of PG⁃CS⁃SS⁃SL show a tendency of slightly increasing firstly and decreasing then with the increase of PG dosage.When PG dosage is 10%,PG⁃CS⁃SS⁃SL has the highest 28⁃day strength,its flexural and compressive strengths reach 6.8 MPa and 32.9 MPa,respectively,and its corresponding water resistance is the optimal with a softening coefficient of 0.904.Water absorption of PG⁃CS⁃SS⁃SL shows a trend of slightly decreasing firstly and increasing then with the increase of PG dosage,reaching the lowest when PG dosage is 10%.Microanalysis shows that the appropriate dosage of PG can promote the formation of C⁃(A)⁃S⁃H gel and AFt in PG⁃CS⁃SS⁃SL system,which optimizes the microstructure of the hardened slurry and facilitates the strength development of the hardened slurry.However,too much addition of PG will lead to the deterioration of the microstructure of the hardened slurry,resulting in the performance deterioration of PG⁃CS⁃SS⁃SL.