粉煤灰和矿粉对水泥基钢渣细集料砂浆体积稳定性的影响研究

Effects of Fly Ash and Slag on Volume Stability of Cement-Based Steel Slag Sand Mortar

针对水泥混凝土用钢渣细集料体积安定性不良的问题,研究了粉煤灰和矿粉对钢渣细集料砂浆(SSM)体积稳定性的改善规律和作用机理。借助砂浆棒法,研究了粉煤灰和矿粉按不同掺量(0%、20%、40%和60%)替代水泥对钢渣细集料砂浆体积稳定性的影响。结果表明:80℃水热加速养护制度下,掺加矿粉和粉煤灰均延长了钢渣细集料砂浆的稳定龄期,推迟了其开裂龄期;以膨胀率大小为依据,粉煤灰和矿粉的最佳掺量均为40%;在标准养护至540d龄期时,掺加粉煤灰和矿粉的砂浆线性膨胀率与空白组的变化规律相近。抗折强度和SEM的研究表明:在水热加速养护制度下,粉煤灰和矿粉对钢渣细集料砂浆体积稳定性的改善主要是通过提高强度以增加砂浆对膨胀力的约束、增加砂浆密实性延缓水分渗入而获得的。因此,在水热养护制度下,掺加粉煤灰和矿粉能改善钢渣细集料砂浆的体积稳定性,但不能从根本上遏制钢渣细集料膨胀组分的水化;在标准养护制度下,粉煤灰和矿粉的改善效果不明显。

Aiming at the volume unsoundness of steel slag sand used in cemented concrete, the improving regularity and mechanism of action on volume stability of steel slag sand mortar （SSM） containing fly ash（FA） and ground granulation blast furnace slag （GGBFS） are investigated. The effects of FA and GGBFS with different dosages（0%, 20%,40% and 60%） on volume stability of steel slag sand mortar are studied. The results show that adding FA and GGBFS can extend the stable age and delay the cracking age of SSM under 80℃ hot water curing. The best dosages of FA and GGBFS are both 40% according to the expansion rate. The linear expansion rate of SSM with FA and GGBFS is the same as the blank sample under the standard curing to 540 days. The results of flexural strength and SEM demonstrate that under the hot water curing, the improving effect of FA and GGBFS on volume stability of SSM is gained by increasing of strength and compactness which can reinforce the restraining force against expansion of SSM and prevent the water penetration. It is concluded that although adding FA and GGBFS can enhance the volume stability of SSM under hot water curing condition, they can＇t prevent the hydration of expansion components of steel slag sand radically. The improving effect of FA and GG- BFS isn＇t obvious under standard curing condition.