Liu Pan, Hai Ran, Liu Junxia, Huang Zhiquan
College of Geosciences and Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450046, China.
School of Architectural Engineering, Zhongyuan University of Technology, Zhengzhou 450007, China.
Materials (Basel). 2022 Apr 26;15(9):3137. doi: 10.3390/ma15093137.
The cement industry has brought serious environmental pollution problems. In the background of ecological civilization, accelerating rational use of waste resources plays an important role in protecting the environment. In this study, self-compacting concrete (SCC) is prepared using fly ash and lime powder as supplementary cementitious materials by replacing 50%, 60%, and 70% of ordinary Portland cement. By systematically analyzing the influence of the fly ash replacement rate on the workability and mechanical properties of SCC, steel-fiber-reinforced SCC containing 60% fly ash is chosen for further study, and steel fiber is added at the percentages of 0.25%, 0.50%, 0.75%, and 1.00%. The performances in fresh and hardened states are investigated in terms of workability, compressive strength, splitting tensile strength, flexural strength, and axial compression deformation property. The obtained outcomes indicate that although the incorporation of fly ash can improve the workability of the mixture, there is a negative correlation between the mechanical properties of SCC and the fly ash replacement rate. For steel-fiber-reinforced SCC containing 60% fly ash, when the content of steel fibers exceeds 0.75%, the workability decreases sharply, and even when the volume fraction is 1.00%, the passing ability cannot meet the requirements of the technical specifications for applications of self-compacting concrete. The analysis results for mechanical properties show that compressive strength is not changed significantly with increasing percentage of steel fibers. The steel fibers strengthen splitting tensile strength and flexural strength significantly, and compared with that of without steel fibers, they increased by 22% and 58%, respectively, with steel fibers up to 1.00%. Additionally, the parameters of the axial compression deformation property are improved by introducing steel fibers, especially the strain energy (Vε) and relative toughness (Γ) of steel-fiber-reinforced SCC containing a high level of fly ash.
水泥行业带来了严重的环境污染问题。在生态文明背景下，加快废弃物资源的合理利用对保护环境具有重要意义。本研究以粉煤灰和石灰粉作为辅助胶凝材料，分别取代50%、60%和70%的普通硅酸盐水泥来制备自密实混凝土（SCC）。通过系统分析粉煤灰取代率对SCC工作性能和力学性能的影响，选取含60%粉煤灰的钢纤维增强SCC进行进一步研究，并分别按0.25%、0.50%、0.75%和1.00%的比例添加钢纤维。从工作性能、抗压强度、劈裂抗拉强度、抗折强度和轴心受压变形性能等方面研究了其新拌状态和硬化状态下的性能。研究结果表明，虽然掺入粉煤灰可提高混合料的工作性能，但SCC的力学性能与粉煤灰取代率呈负相关。对于含60%粉煤灰的钢纤维增强SCC，当钢纤维含量超过0.75%时，工作性能急剧下降，甚至当体积分数为1.00%时，通过能力也不能满足自密实混凝土应用技术规程的要求。力学性能分析结果表明，抗压强度随钢纤维百分比的增加变化不显著。钢纤维显著增强了劈裂抗拉强度和抗折强度，与无钢纤维的情况相比，当钢纤维含量达到1.00%时，劈裂抗拉强度和抗折强度分别提高了22%和58%。此外，引入钢纤维改善了轴心受压变形性能参数，尤其是高掺量粉煤灰的钢纤维增强SCC的应变能（Vε）和相对韧性（Γ）。
