A method for synthesizing early-strength water-reducing agent at room temperature. The preparation method includes the following steps:
1) At room temperature, add unsaturated polyoxyethylene ether and water to the reactor and stir;
2) Add liquid A and liquid B dropwise at the same time, liquid A is unsaturated The mixed aqueous solution of carboxylic acid or acid anhydride, reducing agent and chain transfer agent, the dropping time is 3-3.5h. Liquid B is an aqueous solution of oxidant, the dropping time is 2-2.5h;
3) After dripping and maturing for 1 hour, add sodium hydroxide solution and adjust the pH value to 5-7. Early-strength superplasticizer is obtained by free radical polymerization using water as solvent at normal temperature. The entire synthesis process does not require heating, saving energy and reducing pollution. Its water-reducing performance is better than that of domestic and foreign products, and it can be widely used in industrial production.
Among the building materials, concrete is the largest and most widely used. As the fifth component of concrete, polycarboxylate high-performance water-reducing agent has Its advantages such as good dispersion performance, high water reduction rate, and good plasticity have attracted much attention from the academic community and have been rapidly promoted in recent years. It has been used in major projects such as railways, highways, bridges, tunnels, hydropower, seaports, airports, docks, and civil engineering. middle.
With the continuous consumption of non-renewable energy, the earth will face energy depletion. Usually, the synthesis of early-strength water-reducing admixture requires high-temperature heating, which is a complicated process and requires high reaction equipment. How to reduce the energy consumption in the synthesis of early-strength water-reducing admixture has become an important issue faced by early-strength synthesis.
In recent years, the market demand for early-strength superplasticizers has been increasing, and its research and application have greatly promoted the development of concrete technology and building construction technology. The modernization process, but the progress of construction technology and the continuous development of building structures in the direction of large-scale, complex and functional, have put forward increasingly higher requirements for the performance of concrete, and new water-reducing agents with better performance are urgently needed to be developed.
Traditional early-strength superplasticizer is mainly a comb-type copolymer with a main chain composed of polyacrylic acid copolymer and polyoxyethylene as a side chain. The steric hindrance effect of long side chains controls the agglomeration between cement particles, plays a role in dispersion, and improves fluidity. However, as hydration proceeds, the water-reducing agent molecules will be covered by hydrolysis products, resulting in rapid slump loss. </p
微信扫一扫打赏
