锂渣超高性能混凝土的流动性能、微观和宏观力学性能研究

Flow Properties,Micro-and Macro-Mechanical Properties of Lithium-Slag Ultra-High Performance Concrete

高性能混凝土(UHPC)是一种创新的水泥基复合材料,在拉伸和压缩载荷下具有高机械性能、极低的渗透性和出色的耐久性,预计UHPC在建筑结构中的应用将会逐渐增加。由于其硅酸盐水泥用量高,与传统混凝土相比,UHPC的水化热相对较高。因此,锂渣(LS)可用于UHPC配方,以减少波特兰水泥用量,从而限制水化热,同时解决生态和工程问题。本文分别研究了不同掺量LS对UHPC流动性能、微观和宏观力学性能的影响,并设计了正交试验。锂渣对UHPC流动性能的影响十分显著,早龄期锂渣对UHPC宏观力学性能的影响较小,通过延长养护时间,锂渣对UHPC强度的促进作用进一步体现。纳米压痕试验显示,大掺量的锂渣虽然仍然可以提高UHPC强度,但在一定程度上会降低微观弹性模量。一定掺量的锂渣可以降低UHPC成本的同时提高力学性能,通过正交试验可以获取流动性能和力学性能兼顾的锂渣超高性能混凝土。

Ultra High Performance Concrete(UHPC)is an innovative cementitious composite material with high mechanical properties,very low permeability and excellent durability under tensile and compressive loads.It is expected that the use of UHPC in building structures will gradually increase.Due to its high silicate cement dosage,UHPC has a relatively high heat of hydration compared to conventional concrete.Lithium slag(LS)can therefore be used in UHPC formulations to reduce the amount of Portland cement used,thereby limiting the heat of hydration while addressing ecological and engineering issues.In this paper,the effects of different LS dosing levels on the flow properties,micro-and macro-mechanical properties of UHPC were investigated and orthogonal tests were designed.The effect of lithium slag on the flowability properties of UHPC was significant,and the effect of lithium slag on the macro-mechanical properties of UHPC at early ages was less,and the promotion of the strength of UHPC by the extended maintenance time was further demonstrated.Nanoindentation tests show that a large dose of lithium slag,although still increasing the strength of UHPC,reduces the microscopic elastic modulus to some extent.A certain amount of lithium slag can reduce the cost of UHPC and improve the mechanical properties at the same time.The orthogonal test can obtain a lithium slag ultra-high performance concrete with both flowability and mechanical properties.