Study On Crack Resistance Of High Performance Concrete With Lithium-slag

The mineral admixtures that are mainly in industrial waste is one of the major components of high performance concrete. Our country's main mineral admixtures are fly ashes, granular GGBS and silicon blast furnace slag powder, using these waste residue, we can not only reduce the dosage of cement concrete, but also improve the coordination between concretes and environment.This subject is mainly on grinding fine lithium slag powder (hereinafter referred to as the lithium slag) lithium mineral admixture of concrete. And cement common as cementations material preparation high performance concrete. Due to the excellent lithium slag grinding performance, however which supplied on the market is thicker (specific surface area in 300-400m2/kg), which makes people doubt about the effective function as a high quality admixture, so we need to analyze the compressive strength of concrete that made up of lithium slag with different fineness and its influence of anti-cracking in early age according to the result of the analysis, we could choose the best fineness of lithium slag in different conditions.The experience is studying on lithium slag's effect on the mechanical performance, workability, durability of concrete, and the effect on plastic shrinkage, self-constriction crack of concrete through flattening-cracked test. And using fractal theory to measure and calculate the lithium slag concrete's fractal dimension. And test the shrinkage rate of concrete in its later period time to research lithium slag's effect on drying shrinkage of concrete. In order to analyze lithium slag's mechanism of action to concrete's different performance, and to expound High performance concrete with lithium slag's micro characters influence to macro performance, and we take some test-pieces use microscope scan and analyze. The test results show that:Firstly, in test fineness range, lithium slag concrete intensity with lithium slag fineness increases with increase when it's specific surface area more than 950m2/kg growth slowdown later. But lithium slag early crack-resistance fineness decreases with the increase 950m2/kg, when achieved when it's cracking degree, has increased dramatically. So test 770m2/kg selected fineness lithium slag.Secondly, the admixture of lithium slag in 15% when its reach maximum concrete compressive strength, when more than the value in the compressive strength growth downward trend, the flexural strength and 28d splitting strength in a similar laws. Through the analysis of variance can get water-binder ratio and the admixture of the compressive strength of concrete are particularly significant influence. Lithium slag 28d high-performance concrete 3d and flexural strength of concrete are over a benchmark, so the lithium slag in high performance concrete anti-cracking performance has certain advantages. Thirdly, the admixture of lithium slag in 20 to 25 early concrete crack effects is good. With the improvement of lithium slag concrete admixture of the initial crack, and some delay time concrete crack length and initial setting time, so closely related to its cracking time also has pushed. Lithium slag in 0-20% admixture of changes, concrete crack between total length and the total craze area with the admixture of lithium slag decreased; Lithium slag in the admixture of between 0～25% LieKuan with maximum changes, concrete admixture of lithium slag decreased; Lithium slag to crack a few admixture affect not obvious. Lithium slag concrete as water-binder ratio, crack the reduce of fractal dimension increase, the fractal dimension of the significant growth early concrete anti-cracking performance, the worse. Lithium slag on concrete admixture of little influence on the dry shrinkage rate.Fourthly, Through analyzing SEM, we can know:lithium slag crack mechanism mainly represent in the following two aspects:firstly, It's SO3 in lithium slag react with active Al2O3 or CA3 produced AFt which micro expansion can compensate the concrete's shrinkage crack, and take effect in anti-cracking. Secondly, after putting lithium slag into concretes, we can improve the ITZ's performance observably.