High-energy delay expanding agent for closed concrete and its prepn

Abstract

The present invention relates to one kind of expanding agent with high-energy delay expanding effect on closed concrete and its preparation process. The expanding agent features that it consists of sulfoaluminate cement clinker, steel solution;alag, CaO, MgO, anhydrite, porous ore powder and porous material in certain weight proportion. The expanding agent has high expanding efficacy, long expanding time, low alkali content, high strengthening effect, low cost and simple preparation process.

Description

technical field [0001] The invention belongs to a concrete expansion agent, in particular to an expansion agent with a high-energy delayed expansion function for cement concrete under closed conditions and a preparation method thereof. Background technique [0002] Expansive concrete under closed conditions developed and applied in engineering at present, such as steel pipe high-strength expansive concrete and expansive concrete in the center of mass concrete projects, generally achieves expansion performance by adding expansion agents such as UEA and CAS to the concrete. The hydration time of the expansion agent is relatively early, and the expansion source is single, and the expansion effect on the closed concrete is not high, and the expansion time is mainly manifested in the early stage; in addition, on the basis of UEA and CAS expansion agents, the expansion agent with multiple expansion sources of MgO components is introduced. It is expected to make up for the defects ...

AI Technical Summary

Problems solved by technology

[0002] Expansive concrete under closed conditions developed and applied in engineering at present, such as steel pipe high-strength expansive concrete and expansive concrete in the center of mass concrete projects, generally achieves expansion performance by adding expansion agents such as UEA and CAS to the concrete. The hydration time of the expansion agent is relatively early, and the expansion source is single, and the expansion effect on the closed concrete is not high, and the expansion time is mainly manifested in the early stage; in addition, on the basis of UEA and CAS expansion agents, the expansion agent with multiple expansion sources of MgO components is introduced. It is expected to make up for the defects that UEA and CAS only expand in the early stage and the expansion rate is not high. However, due to the special condition of concrete in a closed environment, external water cannot enter to replenish the water consumed by cement hydration, so the expansion agent due to cement hydration in the late stage Due to the lack of moisture required for the reaction, the hydration reaction cannot produce expansion components, and the post-compensation shrinkage effect on the closed concrete cannot be produced, that is, the delayed expansion effect

Therefore, the expansion energy of the existing expansion agent is not high in the early stage of closed concrete hardening, and its expansion capacity is insufficient in the later stage, so it cannot produce continuous expansion throughout the process of concrete hardening, resulting in shrinkage of the concrete in the later stage

For concrete-filled steel pipe projects, this will directly lead to the debonding of concrete and steel pipe walls, affecting the stability and safety of the entire engineering structure; for large-volume concrete, it will generate tensile stress inside the concrete center. When the tensile strength of volumetric concrete is insufficient to overcome the tensile stress, cracking will occur