Experimental Study On Mechanical Properties Of Concrete Microstructure

On the meso level, we are often seen as a concrete three-phase non-homogeneous composite consisting of the interface region mortar, aggregates and between composition. In concrete characteristics of the interface between mortar and aggregate porosity is greater under normal circumstances, density is relatively sparse compared to mortar this question, the strength and density is far less than the mortar body. So we often this interface is seen as the weakest place concrete. Also known as the "weak link." Concrete mortar-mechanical properties of aggregate interface morphology and macroscopic mechanical properties of concrete damage has important implications. Inside there are a lot of concrete pores and joint surface, the material is brittle nature. Because there are some bleeding effect when concrete pouring grout shrinkage during drying and hampered aggregate, aggregate and mortar bonding surface between then slowly formed a micro-defects and microcracks, so make concrete damage characterized by sudden rupture or collapse. These deficiencies lead to concrete failure process of crack initiation, extension, expansion polymerization until unstable, so these defects are concrete reasons for failure lies. Therefore, the study of the interface of the key concrete damage. We take on Mortar Macro-aggregate interface and two meso-scale test, the mechanical properties of the interface were studied and analyzed the influence of factors, including a look at several aspects:(1) the splitting test of different aggregate surface roughness effects on the interfacial bond strength, and then in the same range of roughness of mortar with different strength were compared. Found the characteristics of ontology of mortar and aggregate surface roughness degree of concrete strength has great influence, also from the interface failure characteristics, starting with the analysis of the interfacial bonding mechanism and failure characteristics, the interfacial bonding strength and the aggregate surface roughness has great relationship, with the aggregate surface roughness increases, the interfacial bond strength is linearly. When the aggregate roughness, mortar strength increases the interfacial bond strength increases.(2) This paper on interfacial elastic modulus of inverse calculation, to study the influence of different fly ash parameters on the interfacial elastic modulus, and calculate the corresponding fly ash parameter interface elasticity modulus is worthy of range, and analysis of the fly ash the modulus of elasticity of concrete and mortar, the influence of Poisson’s ratio, with the increase of the amount of fly ash, concrete Poisson ratio showing a beating is more severe, compared to the Poisson’s ratio of mortar, mortar of Poisson’s ratio is relatively stable, with the increase of the amount of fly ash increases. The interfacial elastic modulus increases with the increase of fly ash content. range and analyzed Effect of fly ash on the elastic modulus of concrete and mortar, Poisson’s ratio, and to analyze its causes.(3) The scanning electron microscopy (SEM) to concrete interface for microscopic observation and microstructure of the interfacial zone of different fly ash parameter, influence on the compactness of concrete, fly ash around C-S-H than general slurry around, the ettringite has certain expansion, they not only to fill the small gaps in concrete, in a certain extent to the filling compacting effect...