Views: 318 Author: su Publish Time: 2018-08-13 Origin: Site
Advantages and disadvantages of polycarboxylate water reducer in application
Polycarboxylate Superplasticizer is a high performance water reducer and a cement dispersant for cement concrete applications. Widely used in highways, bridges, dams, tunnels, high-rise buildings and other projects. The product is environmentally friendly, non-flammable, non-explosive, and can be safely transported by train and car. In many concrete projects, traditional high-efficiency concrete such as naphthalene is less and less able to meet engineering needs due to the limitations of technical performance. A new generation of water reducing agent and polycarboxylate high performance water reducing agent that has attracted much attention at home and abroad. Because it has designed an effective molecular structure based on the mechanism of dispersing cement, it has a super-dispersion type and can prevent concrete slump loss. It does not cause obvious retardation, exerts high plasticizing effect under low dosage, has good fluidity retention, has large freedom of cement to adapt to wide molecular structure, has a large amount of synthetic technology, and has high room for high performance. The effect is remarkable, which can reduce the shrinkage of concrete and the technical properties of extremely low harmful substances, which gives the concrete excellent workability, good strength development, excellent durability, and good performance of polycarboxylate high-performance water reducer. Comprehensive technical performance advantages and environmental protection features meet the needs of modern concrete engineering. Therefore, polycarboxylate superplasticizers are becoming the preferred admixture for the preparation of high performance concrete. According to reports, the use of polycarboxylate admixtures in Japan has accounted for more than 80% of all high-performance admixture products, and North America and Europe account for more than 50%. In China, polycarboxylate water reducers have been successfully applied to large-scale water conservancy, bridges, nuclear power and railway projects in the Three Gorges Dam, Sutong Bridge, Tianwan Nuclear Power Plant, Beijing-Shanghai High-speed Railway, etc., and have achieved remarkable results. At the same time, polycarboxylate water reducing agent also has some problems: 1. Insufficient heat retention in high temperature environment; 2. Strong temperature sensitivity, the same kind of polycarboxylic acid water reducing agent is constructed in different seasons, and the concrete protection property is far apart; 3. Less functional products, it is difficult to meet the requirements of ultra-high, ultra-long-distance concrete pumping, negative temperature construction, preparation of super early strength concrete and high durability of concrete; 4. High viscosity, high blending material, low In the preparation of water-cement ratio concrete, the viscosity of concrete is high, which is not conducive to construction; 5. It is sensitive to the mud content of sand aggregate. 6. The adaptation to the mechanism sand is also poor, and the dosage is sensitive to the construction.