In recent years, with the development of concrete structure toward large span, high level, construction tends to mechanization, which requires concrete must have high mobility, high strength, high durability and other characteristics. This also requires the commercial concrete in high flow state, low water cement ratio with low viscosity and dam fall retention, and with a variety of cement have very good compatibility, to meet the long-distance transportation of concrete, pumping construction requirements.
A.The function of efficient water reducing agent
High efficiency water reducing agent, also known as plasticizing agent, is one of the main admixtures in the process of concrete mixing, the amount of its incorporation is not more than 5% of the quality of cement, mainly the following four aspects :
(1) improve the concrete pouring sex, improve the performance of concrete;
(2) Under given working conditions, reduce the water-cement ratio, improve the strength and durability of concrete;
(3) in the concrete properties and strength unchanged, under the condition of reducing the amount of water and cement, reduce dry shrinkage, the cement hydration heat cause the initial imperfection factors such as high efficiency water reducing agent of cement with a strong dispersion effect, can greatly improve the liquidity of the cement mixture and concrete period, at the same time greatly reduce water consumption, Significantly improve the working performance of fresh concrete and the strength of concrete at various ages; (4) promote the high strength of concrete, ultra-high strength, improve the construction of concrete, to achieve a large volume of modern high-speed civilization construction.
B.classification of water reducing agent
High efficiency water superplasticizer is generally divided into two categories: synthetic single component and composite component. The main control technical indexes include: water reduction rate, air content, setting time, embankment performance, bleeding rate ratio, compressive strength ratio and relative durability index. Among them, reducing water rate for the block passenger degree is the same, the benchmark concrete and admixture concrete unit water consumption difference and the benchmark concrete unit water consumption ratio, is one of the most important quality indicators of water reducing agent.
C. the economy of the use of high efficiency water reducing agent
Adding appropriate water reducing agent in concrete can significantly reduce the water-cement ratio under the condition of maintaining the same workability of fresh concrete; If the water cement ratio of the benchmark concrete is 0.5, the cement dosage in the concrete is 360kg/m3, after mixing with high efficiency reducing water agent, under the condition of phase division phase falling degree, mixing with reducing water rate is 20%, the water cement ratio can be reduced to 40%(the water consumption in the concrete can be reduced 36kg/m3 above). Due to the appropriate amount of water reducing agent, will have a good effect on the strength of concrete, anti-freezing, anti-seepage and a series of physical and mechanical properties. After mixing water reducing agent, the new concrete water reduction rate is generally 6%~10%; If the water reducing agent with strong dispersive ability is added, the water reducing rate can reach 12%~25%.
D. fly ash concrete and water reducing agent
Fly ash concrete has low hydration heat, good workability, high compactness, and can resist a certain degree of chemical erosion, has gradually become a kind of frequently used concrete in construction engineering, such as with all kinds of additives, can improve its performance, and obtain good technical performance and higher economic benefits.
E. development prospect of water reducing agent
Experts predict: the impact of high-performance concrete on the future construction industry is inestimable, the 21st century this kind of concrete will be in more areas of greater development. The research and application of high-performance concrete has just started in the world. At present, China also attaches great importance to its development and application research, but most of them are in the stage of laboratory research.
In the future high-efficiency superplasticizer is beneficial to the development of sulfonic acid based high-efficiency superplasticizer, but not necessarily in their present form. In order to promote its wider application, the copolymerization method has been used to continue to optimize it, and promising products have been shown in research and development. It is expected that only a small part of tea products will be replaced by other products in a period of time.
With the increase of the world's energy and resource conservation requirements, a large number of blast furnace slag, fly ash as cement composite material, such as efficiency water reducing agent to make ultra-fine mineral ginseng materials applied in the preparation of high performance concrete was possible, makes possible the comprehensive utilization of resources and greatly improve the concrete performance, the resulting higher economic and social benefits.