Limestone Powder On Properties Of Concrete

In order to use limestone powder validly in the constructional engineering, the paper analyses the basic properties of limestone powder using the basic theory of concrete material science by means of laboratory test. It studies the influence to the workability and strength of mortar and concrete by adding quantity and fineness of limestone powder. Besides, this paper makes a comparative analysis on the anti-carbonation, dry shrinkage and pore structure of limestone concrete. The research results are as follows:1. In the three degrees of the limestone powder,cement and class II Coal Ash used in the experiments, the content of fine particle whose grain diameter is smaller than 10μm is 40.8%,43.8%,47.2%,20.3%,27.2% and the water requirement is 95.7%,93.9%,91.3%,100%,100% respectively, the content of fine partice of limestone powder is more than that of cement, the filling effect of which can arouse water-reducing effect.2. When the adding of mixing quantity of the limestone power in the mortar is not more than 20%, the activity index of limestone power and the strength factor of cement are both above normal by the use of limestone power with 4.6% 45μm sieve remains. It plays a positive role in unit mass of the cement strength in the whole system.3. The adding content and fineness of limestone powder greatly affect the workability and compressive strength of concrete. Increasing the fineness properly can improve the workability and increase the early strength. If the content is more than 20%, the strength decreases rapidly. Adding the water-decreasing agent can help to improve the fluidness and the strength. When the limestone content of powder with 4.6% 45μm sieve remains is less than 20%, the 28 days' compressive strength is a little less than the normal concrete and the 90 days' compressive strength is nearly the same as the normal concrete.4. The replacement of cement and fine aggregate by limestone powder can improve the workability and water-remain performance. This method is better than replacing the cement by the limestone powder. The exceeding substitution index is about 1.3.5. The capillary porosity of limestone powder concrete is larger than that of the normal concrete. If the mixing quantity is less than 20%, the capillary porosity decreases with the content increases.6. On condition of the same strength, the anti-carbonation properties between the limestone powder concrete and normal concrete is nearly the same. The dry shrinkage of limestone powder concrete decreases when the fineness and the content increases. When the content of limestone powder with 4.6% 45μm sieve remain is 15%, the exceed coefficient is 1.3, the dry shrinkage is smaller than the normal concrete.