Concrete expansive agent

Abstract

The invention relates to the technical field of concrete additives and especially provides a concrete expansive agent which includes, by weight, 12-25 parts of pitchstone ore sand powder, 4-6 parts of sepiolite, 6-12 parts of coal gangue, 20-30 parts of gypsum powder, 6-10 parts of calcium stearate, 3-8 parts of nano aluminium titanate fiber, 6-10 parts of polyvinyl alcohol, 3-5 parts of hydroxypropyl cellulose ether, 1-8 parts of potassium sulfate, and 2-4 parts of ammonium sulfate. The concrete expansive agent is prepared from easy-to-obtain raw materials and has low cost and excellent performance. Through reasonable combination of the raw materials, the concrete expansive agent has the main characters of high blending material use ratio and low cementing material use ratio, and as a result, the concrete expansive agent has excellent workability, high strength, good anti-cracking property and seepage resistance, and long service life.

Description

technical field [0001] The invention relates to the technical field of concrete additives, in particular to a concrete expansion agent. Background technique [0002] As we all know, the construction of subsea tunnels is currently the most complicated and highest-standard construction project in transportation construction; harmful cracks are not allowed in the tunnel concrete, and its maximum buried depth is about -40m. Most of the subsea tunnels are poured with factory prefabricated full-section. The concrete poured at one time is about 3400m3, and the design strength is 56d to C50. Since the tunnel concrete structure needs to withstand high-pressure seawater for a long time, higher requirements are put forward for the impermeability, crack resistance and long-term life of the tunnel concrete. At present, expansion agents are often used to improve the crack resistance of concrete; most of them are ettringites prepared with calcined kaolin, alunite, dickite, aluminum slag, ...

AI Technical Summary

Problems solved by technology

At present, expansion agents are often used to improve the crack resistance of concrete; most of them are ettringites prepared with calcined kaolin, alunite, dickite, aluminum slag, calcium aluminate clinker or calcium sulfoaluminate clinker and gypsum Expansion agent, there are unfavorable factors such as low expansion energy, expansion rate does not match the hydration reaction rate of concrete condensation nuclei, large dosage, high alkali content and easy to cause alkali-aggregate reaction; calcium oxide expansion agent with CaO as the main component, There are disadvantages such as too fast expansion speed, short expansion time, uncoordinated expansion and concrete shrinkage rate, and difficult preservation; magnesium oxide expansion agents with MgO as the main component have slow expansion speed, and the expansion start time is far behind the concrete shrinkage start time. Time, unable to play the role of anti-cracking and other disadvantages