镍铁渣混凝土的力学性能、干缩行为及其与浆体孔结构的关系

制备了不同掺量的镍铁渣混凝土,对其抗压强度、劈裂抗拉强度、弹性模量和干燥收缩进行了测试,并使用压汞法对同配比净浆的孔结构进行了表征。结果表明,镍铁渣混凝土的抗压强度随镍铁渣掺量的提高出现先提高后下降的现象,这与孔结构变化有显著关系。当镍铁渣掺量在20%以上时,混凝土早期强度增长较为缓慢,经90 d龄期养护后基本可以弥补早期形成的强度差。镍铁渣的掺入降低了混凝土的劈裂抗拉强度,但混凝土的弹性模量提高。蒸汽养护可以一定程度激发镍铁渣的活性,但并不能弥补其取代水泥造成的强度损失。20%掺量以内的镍铁渣混凝土具有比纯水泥混凝土较小的干燥收缩,这与镍铁渣掺入后混凝土孔隙率降低、弹性模量提高等相关。

Mechanical Properties,Drying Shrinkage and Their Relation with Pore Structure of Concrete with Ferronickel Slag

Concrete with different FNS(Ferronickel slag) contents was prepared, and its compressive strength, splitting tensile strength, elastic modulus and drying shrinkage were tested. The pore structures of the pastes with the same proportions were analyzed by mercury intrusion porosimetry(MIP). The experimental results show that the compressive strength of FNS concrete increases firstly and then decreases as the FNS replacement goes higher, which has a significant correlation with the change of pore structures. When the FNS replacement is over 20%, the development of strength of FNS concretes is slower than that of plain concrete and this difference can be compensated after 90 days’ curing. Moreover, the FNS weakens the splitting tensile strength but improves the elastic modulus of concrete. The FNS can be partly activated by steam curing, but it cannot cover the loss of strength due to the decrease in cement content. FNS concrete with an FNS content less than 20% has a smaller drying shrinkage than plain concrete, which can be attributed to the lower porosity and the higher elastic modulus of concrete.