碱激发混杂纤维海水海砂混凝土的力学性能研究

Research on the Mechanical Properties of Alkali-Excited Mixed Fiber Seawater and Sea Sand Concrete

摘要:

为解决海洋工程中混凝土材料面临的高碳排放、河砂资源短缺及海水侵蚀等问题，探索了低碳高性能的碱激发混杂纤维海水海砂混凝土的制备与性能优化。试验采用海水海砂替代传统原材料，以不同掺量（0%～7%）的碱激发剂激发粉煤灰（25%～40%）活性，并掺入不同长度（6～18 mm）及混杂聚丙烯纤维，系统研究了多因素耦合作用下材料28 d内的抗压、劈裂抗拉、抗折性能。结果表明，当碱激发剂掺量为5%、粉煤灰掺量为30%时，混凝土抗压强度最优；单掺6 mm聚丙烯纤维（0.9%）可使抗拉与抗折强度分别提升11.3%和9.1%，并显著改善材料韧性与破坏模式，通过纤维桥接作用有效抑制裂缝扩展。该配合比实现了工业固废与海砂资源的高效利用，为低碳耐久的海洋工程混凝土设计提供了理论依据。

Abstract:

To address the issues of high carbon emissions, shortage of river sand resources and seawater erosion faced by concrete materials in marine engineering, the preparation and performance optimization of low-carbon high-performance alkali-activated mixed fiber seawater sea-sand concrete are explored. In the experiments, the seawater and sea-sand are used to replace traditional raw materials. The activity of fly ash (25%~40%) is activated with alkali activators of different dosages (0% to 7%), and the different lengths (6~18 mm) and mixed polypropylene fibers are added to systematically study the compressive, splitting tensile and flexural properties of the material within 28 d under the coupling effect of multiple factors. The results show that the compressive strength of concrete is optimal when the dosage of alkali activator is 5% and the dosage of fly ash is 30%. The addition of 6 mm polypropylene fiber (0.9%) alone can increase the tensile and flexural strengths by 11.3% and 9.1% respectively, significantly improving the toughness and failure mode of the material. The fiber bridging effect effectively inhibits crack propagation. This mix proportion enables the efficient utilization of industrial solid waste and sea sand resources, providing a theoretical basis for the design of low-carbon and durable marine engineering concrete.