工业固废除尘灰基泡沫轻质土耐环境性能研究

Study on the environmental resistance of foamed lightweight soil material from sintered dust

为实现工业固废除尘灰基泡沫轻质土在交通基建中的资源化利用,提出除尘灰基泡沫轻质土的性能提升技术,研发除尘灰基泡沫轻质土新材料,评价复合改性后不同配合比下的除尘灰基泡沫轻质土力学性能、水稳定性能和耐久性能,并探究改性前后材料微观结构变化及其强度形成机制。研究结果表明:非离子型表面活性剂(AEO-9)可显著提升泡沫稳定性和除尘灰的浸润性,最优掺量分别为原状发泡液质量的20%和除尘灰质量的0.4%;复合改性后除尘灰掺量最高为50%,除尘灰基泡沫轻质土28 d强度达到2.08 MPa,吸水率和软化系数别为21.4%和0.765,干湿循环和冻融循环强度损失分别为13.8%和17.3%,满足水稳定性及耐久性指标要求;扫描电子显微镜(SEM)结果表明,复合改性后的除尘灰基泡沫轻质土微观孔隙结构显著优化,直径小于200μm的气泡比例由32.54%提高至52.2%;XRD分析结果进一步表明,在碱性环境下矿渣微粉有助于提高材料初期强度,除尘灰中的Fe_(2)O_(3)在活性激发后有助于材料生成稳定的水化铁铝酸三钙C_(3)(AF)H_(6),进一步提高了材料强度。本文提出的除尘灰基泡沫轻质土改性方法及其新材料为工业固废的资源化利用、回填工程的降本增效提供了新途径。

In order to realize the resource utilization of industrial solid waste dust-based foamed lightweight soil in transportation infrastructure construction,this paper puts forward the performance improvement technology of dustbased foamed lightweight soil and develops a new material of dust-based foamed lightweight soil to evaluate the mechanical properties,water stability and durability of dust-based foamed lightweight soil under different mix ratios after composite modification.The microstructure changes and strength formation mechanism of the material is also explored before and after modification.The results show that the nonionic surfactant(AEO-9)can significantly improve the foam stability and the wettability of the dust,and the optimal dosage is 20%of the mass of the original foaming liquid and 0.4%of the mass of the dust,respectively.After composite modification,the content of dust ash is up to 50%,the 28 d strength of dust ash-based foam lightweight soil reaches 2.08 MPa.The water absorption and softening coefficient are 21.4%and 0.765 respectively.The strength losses of dry-wet cycle and freeze-thaw cycle are 13.8%and 17.3%,respectively,which meets the requirements of water stability and durability index.The results of scanning electron microscopy show that the microscopic pore structure of the composite modified fly ash-based foamed lightweight soil is significantly optimized,and the proportion of bubbles with a diameter of less than 200μm increases from 32.54%to 52.2%.The results of XRD analysis further show that the slag powder is helpful to improve the initial strength of the material in the alkaline environment,and the Fe_(2)O_(3)in the dust is helpful to form a stable hydrated tricalcium aluminosilicate C_(3)(AF)H_(6)after the activation of the activity,which further improves the strength of the material.The dust-based foam lightweight soil modification method and its new materials provide a cost-reduction and efficient way for the resource utilization of industrial solid waste in the backfilling engineering.