活化煤矸石水泥水化机理与性能研究

Hydration Mechanism and Properties of Activated Coal Gangue Cement

近些年来,水泥的低碳化成为国内外的研究热点,利用活性矿物掺和料取代水泥是一种有效降低CO_(2)排放量的方法。为验证活化煤矸石作为水泥矿物掺和料的可行性,研究了活化煤矸石对水泥流变性能、力学性能、水化产物及水化程度的影响,揭示了水胶比、龄期及活化煤矸石掺量等对水泥胶砂试件抗压和抗折强度的影响,并利用XRD、SEM和TG/DTG等表征活化煤矸石对水泥水化产物和微观结构的影响。结果表明,活化煤矸石水泥的流变性能对水胶比的变化更加敏感。将活化煤矸石掺入水泥中,能够有效降低水泥早期的水化速率。活化煤矸石含有大量的活性SiO_(2)和Al_(2)O_(3),具有很强的二次水化反应活性。二次水化产物水化硅酸钙和水化铝酸钙凝胶能够填充水泥机体的孔隙,提升水泥基体的强度。与掺30%(质量分数)石英粉的试件相比,掺30%(质量分数)活化煤矸石试件的28 d抗折和抗压强度分别提升了11.69%和11.82%。

The low carbonization of cement has been a research hotspot at home and abroadand in recent years,using active mineral admixture to replace cement is an effective method to reduce CO_(2) emission.In order to verify the feasibility of activated coal gangue as cement mineral admixture,the effect of activated coal gangue on rheological properties,mechanical properties,hydration products and hydration degree of cement were studied,and the effects of water-binder ratio,age and activated gangue content on compressive strength and flexural strength of cement mortar specimens were revealed.XRD,SEM and TG/DTG were used to characterize the effect of activated coal gangue on hydration products and microstructure of cement.The results show that the rheological properties of activated coal gangue cement are more sensitive to the change of water-binder ratio.The incorporation of activated coal gangue into cement can effectively reduce the early hydration rate of cement.The activated coal gangue contains a lot of activated SiO_(2) and Al_(2)O_(3),and has strong rehydration activity.The secondary hydration products calcium silicate hydrate and calcium aluminate hydrate gel can fill the pores of cement body and improve the strength of cement matrix.Compared with 30%(mass fraction)activated coal gangue sample,the 28 d flexural strength and compressive strength of 30%(mass fraction)activated coal gangue sample increases by 11.69%and 11.82%,respectively.