Mousavinezhad Seyedsaleh, Gonzales Gregory J, Toledo William K, Garcia Judit M, Newtson Craig M, Allena Srinivas
Department of Civil Engineering, New Mexico State University, Las Cruces, NM 88003, USA.
Department of Civil and Environmental Engineering, Cleveland State University, Cleveland, OH 44115, USA.
Materials (Basel). 2023 Mar 25;16(7):2622. doi: 10.3390/ma16072622.
Ultra-high performance concrete (UHPC) is a novel cement-based material with exceptional mechanical and durability properties. Silica fume, the primary supplementary cementitious material (SCM) in UHPC, is expensive in North America, so it is often substituted with inexpensive class F fly ash. However, future availability of fly ash is uncertain as the energy industry moves toward renewable energy, which creates an urgent need to find cost-effective and environmentally friendly alternatives to fly ash. This study investigated replacing cement, fly ash, and silica fume in UHPC mixtures with ground granulated blast-furnace slag (GGBFS), metakaolin, and a natural pozzolan (pumicite). To identify acceptable UHPC mixtures (28-day compressive strength greater than 120 MPa), workability, compression, and flexural tests were conducted on all mixtures. Then, durability properties including shrinkage, frost resistance, and chloride ion permeability (rapid chloride permeability and surface resistivity tests) were evaluated for the acceptable UHPC mixtures. Results showed that 75, 100, and 40% of fly ash in the control mixture could be replaced with pumicite, metakaolin, and GGBFS, respectively, while still producing acceptable strengths. Flexural strengths were greater than 14.20 MPa for all mixtures. For durability, UHPC mixtures had shrinkage strains no greater than 406 μstrain, durability factors of at least 105, and "very low" susceptibility to chloride ion penetration, indicating that these SCMs are suitable candidates to completely replace fly ash and partially replace silica fume in non-proprietary UHPC.
超高性能混凝土（UHPC）是一种具有卓越力学性能和耐久性的新型水泥基材料。硅灰是超高性能混凝土中的主要辅助胶凝材料（SCM），在北美价格昂贵，因此常被价格低廉的F类粉煤灰替代。然而，随着能源行业向可再生能源转型，粉煤灰未来的供应情况不确定，这就迫切需要找到具有成本效益且环保的粉煤灰替代品。本研究调查了用磨细粒化高炉矿渣（GGBFS）、偏高岭土和一种天然火山灰（浮石）替代超高性能混凝土混合物中的水泥、粉煤灰和硅灰的情况。为了确定可接受的超高性能混凝土混合物（28天抗压强度大于120MPa），对所有混合物进行了工作性、抗压和抗弯试验。然后，对可接受的超高性能混凝土混合物评估了包括收缩、抗冻性和氯离子渗透性（快速氯离子渗透性和表面电阻率试验）在内的耐久性性能。结果表明，对照混合物中75%、100%和40%的粉煤灰可分别用浮石、偏高岭土和磨细粒化高炉矿渣替代，同时仍能产生可接受的强度。所有混合物的抗弯强度均大于14.20MPa。在耐久性方面，超高性能混凝土混合物的收缩应变不大于406微应变，耐久性系数至少为105，对氯离子渗透的敏感性为“非常低”，这表明这些辅助胶凝材料是完全替代粉煤灰和部分替代非专利超高性能混凝土中硅灰的合适候选材料。
