Study On The Technology Of Improving Toughness And The Brittleness Of High-strength Lightweight Aggregate Concrete

High-strength lightweight concrete (HSLC) have many characteristics, such as light quality, temperature containing, fire-resistant, antidetonation, durability and so on, which suit for high buildings and bridges. Now this has already received people's great attention. However many characteristics of lightweight aggregate concrete are different from ordinary density concrete, which cause some shortcomings of lightweight aggregate concrete. Compared with ordinary concrete in the same grade, HSLC's toughness and elastic modulus are low and its brittleness is relatively high. This shortcoming has limited its wide application in engineering construction. So how to improve strength and toughness of HSLC becomes focus of civil engineering.In this paper, the cause of brittleness, brittleness destruction characteristic, influence factor, improving toughness technology and mechanism are investigated. On the basis of theory analysis, we have set up the ideal mode of high toughness and strength lightweight aggregate concrete, which sets an important basis for the designation, preparation and produce of HSLC, and we also set up the brittleness destruction model of high-strength lightweight aggregate according to many experimental data. The course of HSLC's destruction includes four stages: elastic stage of line, strengthening stage, stage of falling of stress and soften stage. The influence factors of brittleness of HSLC such as W/B ratio, sand percentage, type of aggregate and binder constitution are analyzed by the experiment: In order to improve the toughness of HSLC, we study the function of fiber, polymer, aggregate and low-layer steel fiber on improving toughness, and explain the mechanism of improving toughness of them.The hydrates and microstructure of HSLC are analyzed by XRD and SEM. The results indicate that polymer in lightweight aggregate concrete forms "interpenetrating polymer cement network structure", which is the reason why polymer light-weight aggregate concrete has fine toughness.