基于正交试验的免蒸压加气混凝土的制备与性能优化

Preparation and performance optimization of non-autoclaved aerated concrete based on orthogonal tests

【目的】制备轻质高强、节能保温的免蒸压加气混凝土,寻找最优制备配合比,提高固体废弃物的利用率。【方法】基于正交试验采用极差分析和矩阵关联分析的方法确定免蒸压加气混凝土的基础最优配比,优化玻璃粉的掺入量来实现加气混凝土性能的提升。【结果】各因素对免蒸压加气混凝土的表观干密度和抗压强度的影响程度由大到小为铝粉掺量(质量分数,下同)、水泥掺量、水料比、聚丙烯纤维(PP纤维)掺量,加气混凝土的基础最优配比为水泥掺量为24%,水料比为0.44,铝粉掺量为0.13%,PP纤维掺量为0.4%;当玻璃粉质量替代率达到25%时,混凝土的综合性能达到最优。【结论】玻璃粉作为粉煤灰的替代材料,在改善免蒸压加气混凝土干密度、抗压强度、导热系数方面效果显著。

Objective With the rapid progress of urbanization,energy consumption in the construction industry has become increasingly concerning.Traditional autoclaved aerated concrete,though widely used,requires high energy during production,conflicting with low-carbon and energy-saving goals.Thus,developing non-autoclaved aerated concrete with low energy consumption and good thermal insulation is a key research direction.This study also seeks to enhance the use of solid waste,particularly waste glass powder.Waste glass,difficult to degrade,poses environmental risks if improperly handled.Incorporating waste glass powder in non-autoclaved aerated concrete not only mitigates environmental pollution but also improves its properties,such as lowering thermal conductivity and increasing compressive strength.This approach aligns with sustainability goals and promotes waste recycling.The research ultimately aims to prepare lightweight,high-strength,energy-efficient,and heat-insulating nonautoclaved aerated concrete,contributing to low-carbon,eco-friendly construction.Methods In this study,orthogonal tests were conducted with two analysis approaches:range analysis and matrix correlation analysis.First,taking dry density and compressive strength as performance indicators,a L16(4^(4))orthogonal experiment was designed examining four factors:cement content,aluminum powder content,polypropylene(PP)fiber content,and watermaterial ratio.Then,range analysis method was used to determine the influence of each factor on the performance of aerated concrete.Matrix analysis was applied to calculate the comprehensive weight of different levels of each influencing factor on multiple performance indicators to determine the optimal ratio for non-autoclaved aerated concrete.In addition,different amounts of glass powder(15%,20%,25%,and 30%)were used to replace fly ash,and their effects on performance indicators such as dry density,compressive strength,and thermal conductivity were investigated.Results and Discussion Aluminum powder had the most significant impact on the dry density and compressive strength of nonautoclaved aerated concrete.With the increase in aluminum powder content,more bubbles formed in the concrete during the gas generation process,weakening the bonding strength between aggregates.As a result,it led to a gradual decrease in dry density and compressive strength.Cement content was identified as the second most influential factor:with the increase in cement content,the compressive strength increased initially but then decreased.This occurred because a certain increase in cement would promote aggregate reaction to generate more hydration products,thereby improving the compressive strength of aerated concrete.However,excessive cement content resulted in excessive hardening and shrinkage,negatively affecting compressive strength.The increase in water-material ratio and PP fiber content showed minimal impact on dry density,with a slight influence on compressive strength.The optimal mix ratio of the foundation was determined to be 24% cement content,a 0.44 water-material ratio,0.13% aluminum powder content,and 0.4% PP fiber content.The introduction of glass powder as a substitute for fly ash reduced the thermal conductivity and improved the strength of aerated concrete.At a replacement rate of 25%,the basic properties of aerated concrete were optimal,with a dry density of 592 kg/m^(3),a compressive strength of 2.6 MPa,and a thermal conductivity of 0.07194 W(/m·K).Conclusion This study shows that aluminum powder,cement,water-to-material ratio,and PP fiber have varying impacts on the dry density and compressive strength of non-autoclaved aerated concrete,with aluminum powder having the most notable effect.Incorporating glass powder as a fly ash substitute significantly enhances both thermal conductivity and compressive strength.The optimal material performance is achieved when the substitution rate of glass powder reaches 25%.While the thermal insulation of the prepared non-autoclaved aerated concrete exceeds current national standards,its compressive strength remains relatively low and requires further optimization.Overall,the study underscores the potential of non-autoclaved aerated concrete for energy efficiency,environmental sustainability,and material performance improvements.However,additional research is necessary to address the compressive strength limitations for practical engineering applications.