Study Of Reactive Powder Concrete Shrinkage Theory And Experimental Research

Reactive powder concrete (RPC) is an advanced composite material. RPC is being paid more and more attention by international engineering circle because of its excellent mechanical properties such as ultra-high strength, high toughness, good durability and low permeability and so on. However, in order to put RPC into actual engineering and learn about its performance in a specific structure, its inherent characteristics must be researched carefully at first.Shrinkage is an inherent time-varying property of concrete. Shrinkage means volume's decreases of concrete component without service load. If the influencing factor of temperature is excluded, shrinkage should include chemical shrinkage, self-shrinkage, drying shrinkage and carbonated shrinkage and so on. Tensile stress will be caused when shrinkage of concrete is under constraints condition. If the tensile stress is more than the maximal value of concrete's tensile strength, concrete will crack and its property will deteriorate. Shrinkage stress of ordinary concrete mainly means drying shrinkage stress; but as high strength and high property concrete are concerned, self-shrinkage shouldn't be omitted because of its high proportion in total shrinkage. RPC is composed by fine aggregate, low water cement ratio and high proportion of silicon. Its self-shrinkage is even larger than drying shrinkage, so the importance of research of its self-shrinkage and drying shrinkage is the same.The dissertation focuses on self-shrinkage and drying shrinkage and stress caused by shrinkage of RPC. In chapter 4, predicted model used for calculating strains of self-shrinkage and drying shrinkage will be given by contrasting and researching the calculation models of shrinkage's strains of ordinary and high-strength concrete and these models are currently dominant at home and abroad. In the chapter 5, based on the predicted calculation formulas given in the chapter 4 and combining with the data out of RPC testing beams and fitting testing data by using mathematical statistics' software, predicted calculation formulas for calculating shrinkage strains of RPC which is used for pouring the testing beams. In chapter 6, self-shrinkage stress and the effect on beams caused by drying shrinkage will be studied specifically basing on the specific calculation formulas of shrinkage strains in the chapter 5 and by analyzing theoretically and building the finite element model of T-shaping beam and then calculating by using the finite element software. The main results of this dissertation are that the predicted calculation models of RPC's strains of self-shrinkage and drying shrinkage will be given and self-shrinkage stress and the prestressed losses caused by drying shrinkage of the testing beams will be calculated based on the previous predicted calculation models of RPC's strains.