碱激发二元/三元复合工业废渣胶凝材料的力学性能与微观机制

Mechanical Performance and Micro-mechanism of Alkali-activated Binary/Ternary Composite Industrial Waste Residues Cementitious Materials

为探究多元工业废渣在碱激发材料力学性能方面产生的协同效应,以水玻璃和氢氧化钠作为激发剂,以粉煤灰(FA)作为基础粉料,粒化高炉矿渣微粉(GGBS)和钢渣微粉(SS)作为外掺复合粉料制备胶凝材料。通过室内试验研究了GGBS、SS和GGBS+SS分别与FA复合及其掺量对标准养护净浆试样抗压强度、抗折强度和弹性模量的影响,并利用扫描电镜(SEM)和压汞(MIP)试验分析了硬化浆体微观形貌和孔隙分布特征的内在机制。结果表明,SS单独掺入会延缓FA基碱激发材料早期(3 d)抗压强度的发展,但与GGBS复合掺入则可弥补其自身不足,从而增强材料抗压强度;单掺40%GGBS时,试样3 d和28 d抗压强度分别增长了152.5%和81.9%,复掺40%(GGBS+SS)时,试样3 d和28 d抗压强度分别增长了89.2%和72.0%;复掺GGBS+SS对早期(3 d)抗压强度的提升效果虽弱于单掺GGBS的情况,但对后期(28 d)抗压强度的促进作用与单掺GGBS基本相当;此外,GGBS单独掺入会造成试样压折比增大,材料脆性增强,而与SS复合掺入则可改善材料的脆性;相同强度条件下,复掺GGBS+SS试样的弹性模量大于单掺GGBS试样,具有更好的抵抗变形的能力;SS单独掺入会降低基体内胶凝产物的生成数量,但与GGBS复合掺入可使试样达到与单掺GGBS试样同等致密水平的微观结构;SS单独掺入会造成基体内部毛细孔增多,孔隙体积增大,与GGBS复合掺入则可使得毛细孔转化为体积更小的凝胶孔,从而促进材料宏观力学强度的提高。

To investigate the synergistic effect of multiple industrial waste residues on the mechanical properties of alkali-activated cementitious materials,this paper took water glass and sodium hydroxide as activators,fly ash(FA)as basic powder,ground granulated blast-furnace slag(GGBS)and steel slag(SS)as additive composite powders to produce cementitious materials.The effects of GGBS,SS and GGBS+SS compounded with FA and their contents on the mechanical properties of standard cured paste samples were studied through laboratory tests,and the internal mechanism of microstructure and pore distribution characteristic of hardened paste was analyzed by scanning electron microscopy(SEM)and mercury intrusion porosimetry(MIP)tests.The results show that although the single addition of SS delayed the development of early compressive strength,the composite addition of GGBS and SS could make up for the deficiency of SS,so as to enhance the compressive strength of the material.With 40%GGBS,the 3 d and 28 d compressive strengths of the sample were increased by 152.5%and 81.9%,respectively,and with 40%(GGBS+SS),the 3 d and 28 d compressive strengths of the sample were increased by 89.2%and 72.0%,respectively.The promotion effect of composite addition of GGBS+SS on the early(3 d)compressive strength was weaker than that of the single addition of GGBS,but the effect of composite addition of GGBS+SS on the later(28 d)compressive strength could reach the same level as that of the single addition of GGBS.In addition,the single addition of GGBS increased the ratio of compressive strength to flexural strength and worsened the brittleness of the material,while composite addition of GGBS and SS could weaken the brittleness of the material.Under the same strength,the elastic modulus of the sample of composite addition of GGBS+SS is greater than that of the sample of single addition of GGBS,which has better resistance to deformation.The single addition of SS would reduce the amount of gelling products in the matrix,while the composite addition of GGBS and SS could make the sample obtain a microstructure at the same level of compactness as the sample with single addition of GGBS.The single addition of SS would increase the amount of capillary pores and the pore volume of the matrix,while the composite addition of GGBS and SS could make the capillary pores transform into gel pores with smaller volume,thus improving the mechanical strength of materials at the macro level.