Study On Microstructure Of Concrete

With the rapid development of the construction technique, the demand for the applied properties of concrete materials have been raising accordingly. For high performance concrete's desired properties include high strength, long durability and good workability, it has been shown remarkably economic in replacing traditional concrete structure and constructing special structure using in harsh environment. The performance of concrete materials relates directly to their microstructure, such as pore structure, interface structure and composition. This thesis mainly analyzes the microstructure of concrete with the application of the image analysis's system with polarizing microscope and microhardness testing machine aiming to probe the relationship between the microstructure of concrete and its properties. Based on this, the research focuses on the following respects:1. To study the effects of ratio of water and cement and mineral additive on the pore structure and the strength of high performance concrete, ordinary concrete and low-strength concrete, with the application of the image analysis's system with polarizing microscope and MIP( method of mercury intrusion pore measurement);2. To research the effects of ratio of water and cement, mineral additive on the interface structure by using microhardness testing machine, and to analyze their effect on the resist compression strength of concrete;3. To probe the combination of hydrated concrete with the application of the image analysis's system with polarizing microscope It can be concluded from the research data that: the porosity values by using the image analysis's system with polarizing microscope and MIP differ from each other but their developmental trends are close;the effect of porosity on the resist compression strength of different kinds of concrete differs;as to high performance concrete, the higher the porosity, the lower the strength will be;as the effects of ratio of water and cement raises and the factors affecting the strength of concrete increase, the effect of porosity declines;the better the interface structure combines, the higher the strength will be;the ratio of water and cement is an essential factor for the interface—as the ratio of water and cement raises, the interface structure notably worsens;While measuring the contents of stones, sands and cement by the image analysis's system with polarizing microscope, the measure error is within 5% when the ratio of water and cement is 0.3;as the ratio of water and cement raises, the error enlarges.In a word, only by improving the microstructure of concrete materials can high performance concrete be composed, the image analysis's system withpolarizing microscope is a direct-viewing, convenient, efficient and effective method for testing the microstructure of concrete;what's more, it is easy to make samples and low at expense, which is of remarkable profit.