Experimental Study On Permeability Of Ultra High Toughness Cementitious Compositesand

A kind of new green building materials, Ultra High Toughness Cementitious Composites (abbreviated as UHTCC) which shows prominent toughness and superior durability, has been successfully applied in many practical projects abroad. It has broad application prospects. The durability of the structure is the key factor to determine the life and the safety of structure, permeability of materials directly affects the durability,it decide the life of structures. Meanwhile, the paper did some experimental study on permeability of UHTCC.The major contributions are summarized as follows:1. This paper introduces the research background and outside present applications of the Ultra High Toughness Cementitious Composites.Then, it outlines the superior crack controlling capacity and the mechanical propertiesof UHTCC.2. Secondly the paper adopts Rapid Chloride Migration (RCM) to determine the chloride diffusion coefficients of UHTCC, and compare with concrete and steel fiber reinforced concrete (SFRC). The results showed that the chloride diffusion coefficients of 28 age's UHTCC is over large, however, with the increase age of UHTCC shows more lower chloride permeability than concrete and SFRC.Then, this paper fits the relationship between the chloride diffusion coefficients and age of UHTCC.3. Adopting Relative Permeability Coefficient to study the water infiltration experiment of UHTCC, and compare with concrete and steel fiber reinforced concrete (SFRC). The results showed that UHTCC is better than C30 concrete and SFRC in water permeability.4. The followed experiments improve the axial tensile test of cement-based materials method, This test combined with the advantages of external clip-on, and paste-type uniaxial tensile test, designing the top of ball and socket connection, the lower ball joints and pins together experimental device. This device can effectively eliminate the initial eccentricity of installing test piece, and has the self-regulatory function to slight eccentricity. The axial tensile test is applicable to fiber cement-based composites which have the strain hardening characteristics of high toughness, high ductility,high energy absorption. This experiments study the basic mechanics parameters and stress-strain characteristics of UHTCC wide plates with different thickness. 5.. The experiments study the mechanical properties and fracture morphology of UHTCC,which is under different tensile strain after unloading.Useing the tests of water-permeable studied the permeability of UHTCC under different fracture morphology,and get the permeability coefficient of varying crack width.Because of the micro-cracks with multi-point crack mode,UHTCC still has a good water permeability in the state of cracked...