轻质多孔结构制备及响应面优化

Preparation and response surface optimization of lightweight porous structures

多孔结构作为新型建筑材料结构,目前依然存在制备材料最佳配比不准确、结构材料与植物相容性差等问题影响其应用。为确定制备多孔结构最佳材料配比,提高其力学强度的同时具有良好植生空间,文章采用轻质多孔火山石作为粗骨料,水泥、粉煤灰、拌合水搅拌而成的胶凝浆体作为胶结剂,制作轻质多孔材料,开展相关的多孔结构制备试验并探究其不同单因素水平下的物理力学性能,得到合理的配合比范围,并采用响应面进行优化,得到满足一定抗压强度、具有良好植生空间及透水性能的最佳材料配合比。结果如下:(1)抗压强度随着水灰比增大呈现先增大后减小的变化趋势,最佳水灰比约0.35,骨料粒径越小,多孔结构抗压强度越高,但为了满足多孔性和透水性,选取2 cm左右的骨料较为适宜;(2)胶凝浆体中胶凝材料由质量占比75%的水泥与25%的粉煤灰组成,并含有0.1%的减水剂,应控制浆体含量为15%~25%,且不应超过30%;(3)根据响应面优化分析,制备多孔结构最优化配合比为:骨料粒径约2 cm,水灰比0.377,胶凝材料体积含量20.7%,在该配比下孔隙率、有效孔隙率和透水系数分别为:38.3%、33.5%、2.98 cm/s。最佳配比下的多孔结构既满足其力学要求,同时具有良好的植物相容性,研究成果可为多孔结构的制备与应用提供科学依据。

As a new type of building material structure,the porous structure still faces problems such as inaccurate optimal ratio and poor compatibility with plants,which affect its application.To determine the optimal ratio of porous structure and improve its mechanical strength while providing a good planting space,this study used lightweight porous volcanic stone as coarse aggregate,cement,fly ash,and water mixed into a cementitious slurry as a binder to produce lightweight porous materials.Relevant porous structure preparation experiments were conducted to explore its physical and mechanical properties at different single factor levels,and then a reasonable range of mix designs was obtained.Response surface methodology was used to obtain the optimal mix ratio of lightweight porous structure with certain compressive strength and good planting space and permeability.The results are as follows:(1)The compressive strength shows a trend of increasing first and then decreasing as the water cement ratio increases.The optimal water cement ratio is located around 0.35.The smaller the aggregate particle size,the higher the compressive strength of the porous structure.However,to meet the requirements of porosity and permeability,selecting an aggregate of about 2 cm is appropriate.(2)The cementitious material in the cementitious slurry is composed of 75%cement and 25%fly ash by mass and contains 0.1%water reducing agent.The dosage should be controlled between about 15%−25%,and should not exceed 30%.(3)Based on the response surface optimization analysis,the optimal mix design for preparing porous structures is as follows:The aggregate particle size is approximately 2 cm;the water cement ratio is 0.377,and the volume fraction of the cementitious slurry is 20.7%.At such design,the porosity,effective porosity,and permeability coefficient are 38.3%,33.5%,and 2.98 cm/s,respectively.The porous structure under the optimal ratio not only meets its mechanical requirements,but also has good plant compatibility,which can provide the scientific basis for the preparation and application of porous structures.