钢渣粉对高强混凝土力学性能和耐久性的影响

Influence of steel slag powder on the mechanical properties and durability of high-strength concrete

超细矿渣是制备高强混凝土的优质矿物掺合料,但是超细矿渣水化放热量较大、凝结较快,不利于高强混凝土的强度和耐久性发展。而钢渣粉具有延缓水泥水化、降低水化放热的作用,可以充当“缓凝剂”。通过在高强混凝土中复掺钢渣粉和超细矿渣,研究了钢渣粉对高强混凝土性能的影响。结果表明复掺15%钢渣粉时初凝时间和终凝时间分别比纯水泥组延长53.0%和35.9%。同时早期强度降低,但与超细矿渣复掺后28 d和90 d强度分别为77.3 MPa和84.6 MPa,比对照组高4.3%和8.6%。此外,钢渣粉有效降低了高强混凝土的绝热温升和自收缩率。单掺15%超细矿渣时7 d自收缩率为1189.63×10^(-6),约为纯水泥组的2.5倍;复掺15%钢渣粉时自收缩率为211.62×10^(-6),比纯水泥组降低了52%。复掺钢渣粉的高强混凝土与纯水泥制备的混凝土的抗氯离子渗透性等级均为“低”。

Ultra fine ground granulated blast-furnace slag is a premium mineral admixture for preparing high-strength concrete.However,its hydration generates substantial exothermic heat and rapid setting,which can impede the development of strength and durability in high-strength concrete.Steel slag powder,on the other hand,can delay cement hydration and reduce the exothermic heat,acting effectively as a“retarder”.It investigates the impact of steel slag powder on high-strength concrete by integrating it with ultrafine slag.The findings reveal that incorporating 15%steel slag powder extends the initial and final setting times by 53.0%and 35.9%,respectively,compared to a pure cement mixture.While early strength decreases,the compressive strengths at 28 days and 90 days reach 77.3 MPa and 84.6 MPa,showing increases of 4.3%and 8.6%over the control group.Additionally,steel slag powder significantly mitigates adiabatic temperature rise and autogenous shrinkage in high-strength concrete.With 15%ultrafine slag,autogenous shrinkage is 1189.63×10^(-6)at 7 d,approximately 2.5 times that of the pure cement group.With 15%steel slag powder,it is 211.62×10^(-6),52%lower than that of the pure cement group.Chloride ion permeability tests categorize the permeability of both steel slag-modified and pure cement concretes as“low.”