掺电解锰渣砂浆的强度与微结构及碳排放分析

Analysis of strength,microstructure and carbon emission of mortar mixed with electrolytic manganese residue

为促进电解锰渣在水泥基材料中的低碳和高效利用,提高水泥基材料的绿色度,运用一系列宏观、微观试验方法,研究电解锰渣等质量取代水泥对砂浆流动性、强度、水化物相及孔隙结构的影响规律,分析电解锰渣在砂浆中的强度贡献,探讨相应的机理。采用碳排放指标,阐明电解锰渣对砂浆的碳排放影响。电解锰渣掺量不大于10%时,可较好地改善新拌砂浆的流动性。电解锰渣对砂浆3 d龄期抗压、抗折强度有较大提高作用,且对抗折强度的提高更为显著,电解锰渣掺量不超过15%时,其对3 d龄期砂浆抗折、抗压强度的贡献系数达1.25以上。随着龄期的增加,电解锰渣对砂浆强度的贡献减弱,但180 d龄期时其抗折强度贡献系数仍在0.5左右。电解锰渣的掺入使砂浆中生成了较多钙矾石相,电解锰渣掺量少于15%时,试件的孔隙结构无明显劣化现象,但随着电解锰渣掺量的增加,体系的孔隙率显著增大。综合考虑碳排放量及复合胶凝体系性能,建立了基于强度性能的碳排放指标。研究结果表明:电解锰渣的加入降低了水泥基材料体系碳排放量,当电解锰渣掺量为10%~15%之间时,水泥胶砂的碳排放指数较低,可以较好地实现水泥基材料的减排要求。

In order to promote the low-carbon and efficient utilization of electrolytic manganese residue in cement-based materials and improve the green degree of cement-based materials,the effects of replacing cement with equal mass of electrolytic manganese residue on the fluidity,strength,hydrate phase and pore structure of mortar were studied in this paperby adopting a series of macroscopic and microscopic test methods.The contribution and mechanism of electrolytic manganese residue to strength in mortar were explored.The influence of electrolytic manganese residue on carbon emission of mortar was expounded by using the carbon emission index.The results show that when the content of manganese residue is not more than 10%,it can improve the fluidity of fresh mortar better.The manganese residue has a greater role in improving the compressive and flexural strength of mortar at the age of 3 d,and the improvement of flexural strength is more significant.When the content of electrolytic manganese residue is less than 15%,its contribution coefficient to the flexural and compressive strength of 3 d mortar is more than 1.25.The contribution of electrolytic manganese residue to mortar strength decreases with increasing age,but the contribution coefficient of flexural strength is still about 0.5 at 180 d age.When the doping amount of electrolytic manganese residue is less than 15%,there is no obvious deterioration of the pore structure of the mortar,but the porosity of the system increases significantly with the increase of the doping amount of electrolytic manganese residue.By considering the carbon emission and the performance of the composite cementitious system,the carbon emission index based on the strength performance was established,and the results show that the addition of electrolytic manganese residue reduces the carbon emission of the mortar.When the doping amount of electrolytic manganese residue is between 10%and 15%,the carbon emission index of mortar is lower and can better achieve the emission reduction requirement of cementitious materials.