山核桃蒲壳生物炭砂浆基本性能及机理研究

Research on Basic Properties and Mechanism of Carya Cathayensis Peels Biochar Mortar

将生物炭用于水泥基材料可改善其基本性能,实现固碳的同时丰富了生物质固废资源化利用的途径。为研究山核桃蒲壳生物炭作为细骨料对水泥砂浆性能的影响规律及作用机理,将其以不同体积分数替代细骨料制备砂浆,对水泥砂浆拌合物的流动性、硬化砂浆的微观结构、基本力学性能及保温性能展开试验研究。结果表明:1)拌和时添加25%(占生物炭质量分数)的水作为附加用水,拌合物的工作性最稳定。2)生物炭25%(体积分数)替代砂时,骨料周围可形成良好的浆体握裹及界面过渡区,使砂浆试件抗折强度和抗压强度最高;随着砂替代率的增加,砂浆试件的强度均逐级减小。3)随着生物炭用量的增加,水泥砂浆导热系数呈显著的逐级下降趋势,生物炭的原生孔隙延长了热传导路径,并发挥了慢导热作用,添加生物炭可显著提高水泥砂浆的保温隔热性能。

The use of biochar in cement-based materials can improve their basic properties and achieve carbon sequestration while enriching the ways of resource utilization of biomass solid waste.To study the effect of carya cathayensis peels biochar on mortar’s performance,including fluidity,microstructure,basic mechanical properties and thermal insulation,mortar samples whose fine aggregates were partially or completely replaced by carya cathayensis peels biochar were prepared.The experiment results suggest that:1)the best workability of the mix is found with extra water addition at the rate of 25%of biochar by mass.2)The highest flexural and compressive strength are found in mortar with 25%biochar-sand-replacement by volume fraction,which has a better interfacial transition zone and paste-wrapping around the aggregates particles,beyond this addition.With the increase of sand substitution rate,the strength of mortar specimens decreases step by step.3)The thermal conductivity of cement mortar presents a significant decreasing trend with the increase of biochar addition.The native pores of biochar prolong the heat transporting path and exhibit the effect of slowing down thermal conduction which significantly improve the thermal insulation and heat preservation performance of cement mortar.