The raw materials of concrete were only cement, water and gravel. In order to save cement and improve the performance of concrete, mixing concrete is often mixed with a gel -coagulated grain blast furnace residue and the coal ash produced by the thermal power plant after grinding. Mineral products that are in short supply now. However, with the rapid development of domestic and foreign engineering construction in recent decades, it has gradually faced the problem of tight pink and coal ash. In my country, such problems have also occurred, especially in the southwestern region, the supply of ash supply is tight, and other areas often occur in the formation of flour and coal ash. Therefore, it is necessary to find a new type of mixture that is easy to obtain and quality and low price. In recent years, with the depletion of natural sand resources, the application of artificial sand has become widespread, and then a new industrial waste has also produced a new industrial waste.
Because people lack the understanding of stone powder and believe that it is harmful to concrete, it cannot be used. This not only causes waste of resources, but also causes environmental pollution. The accumulation of abandoned stone powder occupies a large amount of land. How to deal with it is an urgent problem. Therefore, the use of these stone powder and reasonable use can not only eliminate the pollution of the stone powder to the environment, but also can also take care of the production and use of mechanism sand. The formation process of stone powder makes it a large ratio area, generally above 600m2/kg, making it possible to apply it as a mixture in concrete. In recent years, stone powder has gradually become a trend in concrete.
1. The mechanism of stones in concrete
There are two main opinions on the mechanism of stone powder in concrete: one view is that stone powder is not activated and has a filling effect in the concrete. The stone powder has a certain filling effect on the gel material, which can improve the interface structure of the pore characteristics, slurry and collection of the concrete; another point of view is that the stone powder has a certain volcanic ash activity and can exert the volcanic ash effect. In addition to the above two effects, stone powder can also participate in cement hydration reactions, which has a certain impact on the workingality and durability of concrete. According to the mechanism of stone powder, the replacement part of the fine material in the concrete can be used as a mixing concrete mixing material in the concrete.
2. The stone powder part replaces fine aggregate
The stone powder can fill the dense and micro -ingredient effect within a certain amount of amount, and can significantly improve the ease of concrete, and the condensation time of concrete has almost no effect. It can reduce the amount of cement and reduce the temperature rising temperature, which is very favorable for reducing temperature stress and improving concrete cracking performance. In my country, hydropower projects such as Pingding, Rock Beach, Jiangyu, Fenhe, Baishi, and Huang Dan have adopted stone powder instead of some fine aggregate and achieved good results.
Some domestic scholars have proposed the research on cement, coal ash, and stone powder composite composite gel materials. The "filling effect" between the particles of cement, coal ash, and stone powder, the gap between the particles is reduced, the gap water is reduced, and the free water increases, the fluidity of the slurry increases. They study the effects of cement, coal ash, and stone powder ternary powder system on the fluidity and degeneration of the slurry. The optimized and cooperative ratio proposed by the test is: 34%of the cement, 23%of the grinding manganese iron slag, and 43%of the limestone powder. Trichous composite gel material. Many studies in this regard are carried out in combination with actual projects. The main way is to use stone powder (or high stone powder in sand). The particle size of stone powder is usually below 80 μm. The common indicators of frozen performance are performed.
In the crushing concrete dam -building material, the flour ash has a pivotal position. The role of the ash in the concrete is mainly due to the second hydration reaction of the CA (OH) 2 generated by the cement hydration. Gaps, improve concrete and easy. The characteristics of crushing concrete dams in my country are the dosage of low gel coagulation materials and high -powered coal ash (50%~ 70%). If the same slump is to be maintained, the amount of concrete mixed with stone powder can be reduced, which will affect the many properties of concrete. Stone powder is a material that is easy to obtain and cheap. It will also bring a lot of stone powder during the processing process of aggregate. If it is not used, it will not only take up the venue stacking, but also cause pollution to the environment. If it can be used as a blending material for mixing materials, it can replace the increasingly scarce powder and coal ash and relatively expensive silicon powder or slag, which will be major Reality significance.
3. Stone powder as a concrete blending material
3.1 The feasibility and significance of stone powder as a concrete blending material
Traditional opinions believe that stone powder is a kind of inert material with small fineness. It can not only supplement the lack of fine particles in the concrete, increase the proportion of the surface area of the solid to the water volume, thereby reducing water and departure. Form a soft pulp with water to improve the concrete and easyness.
3.2 Application of the application of stone powder as a concrete mixing material at home and abroad
In some hydropower projects, my country has adopted stone powder as a mixture to replace some cement, which has been successfully applied. For example, the Longtan Hydropower Station uses stone powder to replace 25%of powder and coal ash, and is used as a concrete blending material, which has little effect on the VC value of crushing concrete. Essence When the content of the experiment is about 18%, the crushing concrete mixing and the properties of the object have been significantly improved, and it can be further improved. Micro -stone powder has become an important part of crushing concrete mixing material. A large number of research abroad has also conducted a lot of research. For example, the Chiyaka dam in Japan, that is, replaced 55%of the powder and coal ash with stone powder for crushing concrete. The conclusions obtained abroad are basically the same as the domestic results. The stone powder can promote the macro performance of concrete to a certain extent.
3.3 Insufficient research at home and abroad
At present, the application of stone powder as a mixing material has less research. The main content of the research is the impact of the macro performance of concrete. The hydration characteristics of the micro structure, the hydration of the gel material system, and the mechanism of the role of stone powder in the hydration of the gel material system are The research work has not been fully carried out. Because stone powder can be used as a major practical significance in the future blending material and the current research on the hydration characteristics of crushing concrete composite gel materials with mixing stone powder, it is necessary to do a more comprehensive and in -depth research on it, which can greatly promote it to greatly promote it As the application of stone powder as a blending material in crushing concrete, it will play a huge role in reducing environmental pollution, reducing engineering costs, alleviating the resource crisis, and promoting the sustainable development of my country's national economic construction.
4 Conclusion
In areas where powder and coal ash is relatively scarce, or long -distance transportation of powder and coal ash affects crushing concrete and dams economy, it can be used to crushed concrete with stone powder instead of some powder and coal ash. The environment can also reduce the temperature ascension of concrete, improve the harvesting and crushing of crushing concrete, have good economic and social benefits, and help improve the cracking of large volume of crushing concrete. Therefore, considering the use of stone powder to replace some fine aggregate or use stone powder as a mixing material with crushing concrete instead of some powder and coal ash, designing the cooperation ratio to meet the construction requirements is completely feasible.
