摘要
本文研究了不同煅烧温度(200℃和 800℃)电解锰渣(EMR)火山灰活性及掺入 0wt％、10wt％、20wt％EMR水泥胶砂在 80℃蒸汽养护 7 h、7 d和标准养护 3 d、28 d条件下力学性能、水化产物与孔隙特征分布.采用低场核磁共振技术、XRD定量表征及SEM微观形貌共同揭示了EMR对水泥胶砂的水化产物、孔径分布及孔隙率等影响规律,并探究了不同养护条件对EMR水泥胶砂水化进程的影响.结果表明:800℃煅烧EMR火山灰活性明显高于 200℃煅烧火山灰活性,当 800℃煅烧EMR替代量为 10wt％时,初凝、终凝时间和标准稠度用水量分别为对照组的 1.52、1.06和 1.05 倍,而蒸养 7 h、7 d抗压强度分别高于标准养护 3 d和 28 d抗压强度,而抗折强度仅仅在蒸养 7 d时高于对照组 17.3％;纯水泥胶砂的水化产物主要为纤维状水化硅酸钙(C-S-H)凝胶和片状氢氧化钙(CH),而EMR水泥胶砂中由于硫酸盐含量较高,除了上述水化产物之外,在蒸养或标准养护条件下均可观察到石膏相与针棒状钙矾石(AFt)的存在,标准养护 28 d时,CH、AFt和无定性含量分别为 14.50％、11.75％和 46.25％,与蒸养 7 d衍射峰基本相似.另外,蒸汽养护 7 h与标准养护 3 d对比孔隙率减少 1.44％,蒸养 7 d与标准养护28 d对比孔隙率减少 0.06％.综上,蒸汽养护可以提高 800℃煅烧EMR火山灰活性,同时还可以加速EMR水泥胶砂的水化进程和细化其内部孔结构,进而提高胶砂的力学性能.
Abstract
The pozzolanic activity of electrolytic manganese residue(EMR)at different calcination temperatures(200℃and 800℃),and the distribution of mechanical properties,hydration products,and pore characteristics of cement mortar with 0wt％,10wt％and 20wt％EMR,subjected to 80℃steam curing for 7 h and 7 d,as well as standard curing for 3 d and 28 d,were studied.The effects of EMR on the hydration products,pore size distribution and porosity of cement mortar were revealed by low field nuclear magnetic resonance technology,XRD quan-titative characterization and SEM microstructure.The effects of different curing conditions on the hydration process of EMR cement mortar were also investigated.The results show that the pozzolanic activity of EMR calcined at 800℃is significantly higher than that of EMR calcined at 200℃.When the substitution amount of EMR calcined at 800℃is 10％,the initial setting time,final setting time and water requirement of normal consistency are 1.52,1.06 and 1.05 times than that of the control group,respectively.The compressive strength of steam-cured 7 h and 7 d is higher than that of standard-cured 3 d and 28 d,respectively,while the flexural strength is only 17.3％higher than that of the control group at 7 d.The hydration products of pure cement mortar are mainly fibrous hy-drate calcium silicate(C-S-H)and sheet-like calcium hydroxide(CH),while in EMR cement mortar,due to the high sulfate content,in addition to the above hydration products,the presence of gypsum phase and needle shaped ettringite(AFt)can be observed under steam curing or standard curing conditions.The CH,AFt and amorphous contents are 14.50％,11.75％and 46.25％after 28 d of standard curing.These values are similar to the diffraction peaks after 7 d of steam curing.In addition,the porosity of steam-cured 7 h is 1.44％lower than that of standard curing 3 d,and the porosity of steam-cured 7 d is 0.06％lower than that of standard curing 28 d.In summary,steam curing can improve the pozzolanic activity of EMR calcined at 800℃,accelerate the hydration process,and refine the internal pore structure,thereby improving the mechanical properties of the mortar.
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