Mixture Properties And Volume Deformation Of High-strength Shale Ceramsite Lightweight Aggregate Concrete

With the rapid development of modern bridge engineering going towards large-span bridges, the bigger dead weight of ordinary concrete becomes a bottleneck restricting the development of bridge engineering. In recent years, industrial residue and urban waste are utilized to produce high strength ceramsite. Mass green lightweight aggregate replacing natural aggregate were used to prepare lightweight aggregate concrete, making up the limitation of ordinary concrete in bridge engineering due to its lightweight, high-strength and low water absorption in performance. In this paper, workability and volume deformation lightweight aggregate concrete were investigated, obtaining the following conclusions:(1)High-strength shale ceramsite was selected as coarse aggregate to design initial mix proportion based on loose volume method, and then based on single factor test to consider the influence of each factor on workability and mechanical strength, modifying the initial mix proportion.(2)Based on mix proportion, the influencing law of mixture performance were studied from the following aspects: prewetting time, particle type, fly ash, and fineness modulus,receiving the main factors that effect the performance of lightweight aggregate concrete.(3)This paper focused on the mechanical properties and volume deformation of lightweight aggregate concrete. As the test results showed, with the addition of fly ash, the early autogenous shrinkage of lightweight aggregate concrete were restrained obviously,meanwhile, the more and finer fly ash, the better effect shrinkage reduction gotten; prewetting aggregate could obviously improve early volume deformation; Industrial computed tomography scanning system was introduced to detect inner cracking of lightweight aggregate concrete, the specimens structure destroyed under the continuous load, while crack propagation path kept pace with the loading direction and the failure surface is mainly throughout the aggregate rather than propagating along the mortar-aggregate interface transition zone.(4)Based on elliptical ring method and slab test, focusing on volume deformation of fly ash lightweight aggregate concrete admixing steel fiber, with the increase of steel fiber,shrinkage reduction, compressive strength and splitting tensile strength improve are improved to some extent; failure mode of lightweight aggregate concrete admixing steel fiber changed,wherein specimens cracked but not showed loose, presenting integrity.