At present, Travertine Stone many project construction projects are limited by the cost of transportation of materials. It is necessary to use the local inert or partial active stone powder instead of fly ash in concrete design and must meet the construction requirements of mass concrete. Concrete mixed with stone powder, from a certain point of view is equivalent to improve the artificial sand in the stone powder content, Travertine Stone can not be used as a plastic material, stone powder is only part of its filling role. National standards on the mixing of stone powder content to do a strict limit, excessive content of stone powder on the performance of concrete has a negative impact.
At present, from the production mechanism of sand statistics, the untreated mechanism of gravel powder content is generally about 30% to 45%, far greater than the requirements of the specification, the excess stone powder, through screening and washing the way to clear the data Shows that the United States each year four billion tons of stone powder is accumulated in the quarry near the domestic although there is no statistical data, but in recent years the large-scale advance of domestic infrastructure, followed by the number of stone powder will reach billions / Scale, such a large-scale accumulation of stone powder, the number of increasing, Travertine Stone over time the pollution of the environment will become more and more serious.
The gradation and specific surface area of the stone powder are characterized by fineness (45μm square hole sieve). The gradation (45μm square hole sieve) is used to characterize the gradation or presence of stone powder The results show that when the specific surface area of stone powder reaches a certain degree, grinding fine stone powder can replace cement with Ⅱ grade fly ash instead of cement strength. Travertine Stone When the fineness of stone powder reaches nanometer level, the material performance will change qualitatively. Therefore, with the specific surface area to characterize the fineness of stone powder more scientific.
At present, the research on the application of stone powder in China is mainly focused on the challenge of the limitation of stone powder content. It is more demanding that the strength performance of stone powder concrete is required, and the requirement of cracking performance is obviously insufficient. The biggest problem is the application of stone powder in concrete. Reduce the crack resistance of concrete, Travertine Stone such as the ultimate tensile value decreased significantly, the elastic modulus increased more. Mass concrete design should be the first indicator of crack resistance as a consideration, silica powder given the maximum content of 30% of the powder, through the concrete test, the impact of cracking performance is too great. At present, Travertine Stone there are few cases of large volume of concrete mixed with 30% stone powder engineering applications.
Surface modification technology is a chemical, Travertine Stone physical method to change the chemical composition of the surface of the material or organizational structure to improve the performance of a class of material processing technology. There are four main methods of surface modification: mechanical chemical modification, coating method, coupling agent method and inorganic nano-coating modification method.
1) limestone powder as a product, quality indicators such as water content, fineness, calcium carbonate content, mud content should be described (the restrictions on the specification to limit), and the quality indicators to be stable;
(2) the amount of limestone powder, Travertine Stone according to the specific project of the external environment, construction site, durability requirements, such as through the test to determine;
(3) limestone powder, as a kind of admixture, should generally be mixed with fly ash or mineral powder, for the superposition of "morphological effects, Travertine Stone micro-aggregate effect and activity effect" to create conditions;
(4) the emergence of concrete on the market today, "strong agent", "synergist", "enhancer", "glue" and other new concrete auxiliary admixtures, such admixtures are generally excited concrete admixture of water The role of the mix can be considered to play the role of limestone powder as a new admixture;
(5) concrete laboratory, Travertine Stone for the new admixture of limestone powder, should do more experiments, repeated verification, a comprehensive study of concrete long-term mechanical properties, durability, to ensure the quality of the project.