The 1 main problems of the current use of micro silica fume in the presence of
The micro silica fume in concrete application, greatly improves the strength and durability of concrete, in key projects, the special condition of the engineering structure or part of the project has a special significance. However, there are several major issues as follows:
One is high cost, because at present, the use of micro silicon powder concrete of concrete special requirements, micro silica fume content multi in more than 10% and micro silica fume itself higher prices, about is 5 to 10 times the price of cement, and add the corresponding of fly ash and other low price adding dosage of materials generally lower, below 20%.
Second the micro silica fume concrete due to the micro silica fume admixture of higher and silica fume encryption, as the silica fume in concrete can be uniformly dispersed, construction requires the use of construction technology of wet mixing decryption, coming encryption of silicon powder and water 1:1 (weight ratio) mixed high speed stirring to decrypt, wet doped decrypted form containing 50% silica fume of a homogeneous slurry. In addition, in order to ensure the silica fume slurry uniformity and stability, quality excellent slurry stabilizer added in the mixing process, slurry stabilizer are mostly imported, dosage is 1% (weight percentage of silicon slurry total). These special equipment and additives can not meet the general construction.
Three is due to the addition of high content of micro silica fume mixed great changes took place in the nature of concrete, such as flow, coagulation time, dry shrinkage performance and so on.
2, this research to solve the problem and purpose
2.1 the purpose of this study and the main problems to solve a large number of literature and engineering examples show that although the construction industry from design, construction and other aspects of a large number of research, but limited to the concrete material itself, the main improvement is still concentrated in the external waterproof, but the existence of waterproof material, waterproof material, such as the joint processing technology, and so is still a large number of underground leakage. In view of the shortcomings of the above, we believe that we must start from the concrete material itself, improve the concrete itself, and improve the performance of the concrete itself.
2.2 the materials of this study, as mentioned above, should be solved in the problem of leakage in the basement. And to improve the permeability of concrete material, from the micro, it is to reduce the gap in the concrete. To reduce the communication gap, we must use more than cement fine materials, in this study, choose to use the micro silicon powder.
While taking into account micro silica fume incorporation will improve the mixing of concrete strength, but generally in the basement and the concrete strength is not high and micro silica fume cost high, the incorporation amount of concrete performance will produce negative influence, so micro silica fume dosage is unfavorable.
In addition, taking into account the need to solve the problem of leakage of basement, the research and development of anti permeability concrete cost is not too high, to control the overall cost is not more than the original concrete and waterproof material price, in order to ensure the strength of concrete, in the concrete mixed with fly ash, steel slag and other construction materials, to replace cement, reduce cement dosage, reduce project cost.
Third, considering the micro silica fume particles finer, larger specific surface area, in order to ensure the performance of concrete in the same conditions, the unit mass of water is greater, according to contrast experiment to determine the unit mass micro silica fume cement water volume ratio, according to the quality of microvascular doped silica fume, economizes the water to ensure the workability of concrete.
