摘要
为应对砂石资源的日益匮乏,探索再生细骨料完全替代天然细骨料制备再生混凝土的可行性。以立方体抗压强度和劈裂抗拉强度作为评估指标,采用粉煤灰取代率(A)、水胶比(B)、砂率(C)、再生粗骨料取代率(D)和空列(E)作为参数设计五因素四水平正交试验,结合试件破坏形态、试验数据的极差与方差分析及扫描电子显微镜(SEM)微观结构观察,系统分析各因素影响机制,从而为优化配合比设计提供理论支撑。试验结果表明:再生骨料因微裂缝多、强度低,相较天然骨料断裂数量更多且断裂面不平整,各因素对抗压与劈裂抗拉强度的影响程度大小排序一致,即再生粗骨料取代率(D)>水胶比(B)>粉煤灰取代率(A)>砂率(C),强度随粉煤灰取代率(A)、水胶比(B)和砂率(C)的增大先增后减,随再生粗骨料取代率(D)的增加持续下降;借助SEM对照不同配比发现,强度较高的配比其微观结构呈现高度的密实性;最佳配合比为A2B2C3D1,即粉煤灰取代率为10%、水胶比为0.36、砂率为0.40、再生粗骨料取代率为30%;此外,细骨料全再生的不同砂率对力学性能影响最小,这为废弃混凝土的有效利用提供了重要参考。
To address the increasing scarcity of sand and gravel resources,this study explores the feasibility of completely replacing natural fine aggregates with recycled fine aggregates in recycled concrete production.Using cube compressive strength and splitting tensile strength as evaluation indicators,a five-factor four-level orthogonal test was designed with parameters including fly ash replacement ratio(A),water-binder ratio(B),sand ratio(C),recycled coarse aggregate replacement ratio(D)and empty column(E).The experimental analysis incorporated failure patterns,range and variance analysis of test data,and scanning electron microscopy(SEM)microstructure observation to systematically analyze the influencing machanism of various factors to optimize mix proportion design.The results indicate that recycled aggregates exhibit more fractures and uneven fracture surfaces compared to natural aggregates due to numerous microcracks and lower strength.The factors influencing compressive and splitting tensile strength followed the same order of significance as shown below:recycled coarse aggregate replacement ratio(D)>water-binder ratio(B)>fly ash replacement ratio(A)>sand ratio(C).Strength initially increased and then decreased with higher fly ash replacement ratio(A),water-binder ratio(B),and sand ratio(C),while continuously decreasing with increased recycled coarse aggregate replacement ratio(D).SEM comparisons revealed that higher-strength mixes demonstrated denser microstructures.The optimal mix proportion was determined as A2B2C3D1,corresponding to 10%fly ash replacement,0.36 water-binder ratio,0.40 sand ratio,and 30%recycled coarse aggregate replacement.Notably,different sand ratios in fully recycled fine aggregates showed minimal impact on mechanical properties.The study results could provide critical references for effective utilization of waste concrete.
作者
高飞凡
石振武
徐传浩
邓春瑶
GAO Feifan;SHI Zhenwu;XU Chuanhao;DENG Chunyao(School of Civil Engineering and Transportation,Northeast Forestry University,Harbin 150040,China;School of Architecture and Engineering,Hulunbuir University,Hailar 021008,China)
出处
《甘肃科学学报》
2025年第6期47-54,共8页
Journal of Gansu Sciences
基金
呼伦贝尔市基础研究和应用基础研究项目(GH2024010)
呼伦贝尔学院横向科研项目(HHX2024-0001)。
关键词
再生细骨料
扫描电镜
正交试验
抗压
劈裂抗拉
Recycled fine aggregates
Scanning electron microscopy
Orthogonal test
Compression resistance
Splitting tensile
