Li Hongbo, Zhang Hubiao, Yan Pengfei, Yan Changyu, Tong Yufei
College of Civil and Hydraulic Engineering, Ningxia University, Yinchuan 750021, China.
Ningxia Research Center of Technology on Water-Saving Irrigation and Water Resources Regulation, Yinchuan 750021, China.
Materials (Basel). 2021 Nov 22;14(22):7103. doi: 10.3390/ma14227103.
The mechanical properties and strength formation mechanism of cement-fly-ash-stabilized slag-coal gangue mixture were examined using an unconfined compressive strength test, splitting strength test, triaxial test, and scanning electron microscopy to solve the limitations of land occupation and environmental pollution that is caused by fly ash from the Xixia District thermal power plant in Yinchuan, slag from the Ningdong slag yard, and washed coal gangue. Its performance as a pavement base mixture on the road was investigated. The results demonstrated that as the slag replacement rate increased, the maximum water content increased while the maximum dry density decreased. The addition of slag reduced the unconfined compressive strength and splitting strength of the specimens; furthermore, the higher the slag substitution rate, the lower the unconfined compressive strength and splitting strength of the specimens. As the cement content increased, the specimen's unconfined compressive strength increased. Based on the principle of considering the mechanical properties and economic concerns, the slag replacement rate in the actual construction should be ~50% and should not exceed 75%. Based on the relationship between the compressive strength and splitting strength of ordinary concrete, the relationship model between the unconfined compressive strength and splitting strength of cement-fly-ash-stabilized slag-coal gangue was established. The failure mode, stress-strain curve, peak stress, and failure criterion of these specimens were analyzed based on the triaxial test results, and the relationship formulas between the slag substitution rate, cement content, peak stress, and confining pressure were fitted. As per the SEM results, the mixture's hydration products primarily included amorphous colloidal C-S-H, needle rod ettringite AFt, unhydrated cement clinker particles, and fly ash particles. The analysis of the mixture's strength formation mechanism showed that the mixture's strength was the comprehensive embodiment of all factors, such as the microaggregate effect, secondary hydration reaction, and material characteristics.
通过无侧限抗压强度试验、劈裂强度试验、三轴试验和扫描电子显微镜，研究了水泥 - 粉煤灰 - 稳定矿渣 - 煤矸石混合料的力学性能和强度形成机理，以解决银川西夏区热电厂粉煤灰、宁东渣场矿渣和洗选煤矸石造成的占地和环境污染问题。研究了其作为道路路面基层混合料的性能。结果表明，随着矿渣替代率的增加，最大含水量增加而最大干密度降低。矿渣的加入降低了试件的无侧限抗压强度和劈裂强度；此外，矿渣替代率越高，试件的无侧限抗压强度和劈裂强度越低。随着水泥含量的增加，试件的无侧限抗压强度增加。基于考虑力学性能和经济因素的原则，实际施工中矿渣替代率应为~50%，且不应超过75%。根据普通混凝土抗压强度与劈裂强度的关系，建立了水泥 - 粉煤灰 - 稳定矿渣 - 煤矸石无侧限抗压强度与劈裂强度的关系模型。基于三轴试验结果分析了这些试件的破坏模式、应力 - 应变曲线、峰值应力和破坏准则，并拟合了矿渣替代率、水泥含量、峰值应力和围压之间的关系式。根据扫描电子显微镜结果，混合料的水化产物主要包括无定形胶体C - S - H、针棒状钙矾石AFt、未水化的水泥熟料颗粒和粉煤灰颗粒。混合料强度形成机理分析表明，混合料的强度是微集料效应、二次水化反应和材料特性等所有因素的综合体现。
