High efficiency composite expanding agent for high-strength self-stressing concrete filled steel tube and preparation method thereof

Abstract

The invention belongs to the building field, and concretely relates to a high efficiency composite expanding agent for a high-strength self-stressing concrete filled steel tube and a preparation method thereof. The high efficiency composite expanding agent comprises the following components by mass percentage: 22-40% of light calcined magnesia, 12-25% of active calcium oxide, 6-14% of calcined dolomite, 18-30% of sulphoaluminate cement clinker, 12-18% of natural gypsum and 2-6% of modified meerschaum powder. Through a design of hydration expansion characteristics of different components, expansion performance and high-strength concrete intensity are cooperated for development, expansion usefulness is high, water for hydration is little, expansion beginning time is early, and the expansion performance is stable, by introducing a maintenance material, problems of difficult maintenance of a steel pipe under enclosing condition and difficult supply of expanding agent and water for concrete hydration can be solved, and the high efficiency composite expanding agent is suitable for preparing the high-strength self-stressing concrete filled steel tube under enclosing condition of the steel pipe.

Description

technical field [0001] The invention belongs to the field of construction, and in particular relates to a high-efficiency composite expansion agent suitable for high-strength self-stressed steel pipe concrete and a preparation method thereof. Background technique [0002] Due to its unique combined structural advantages, CFST has gradually been widely used in the construction field. As the building structure gradually develops towards super high-rise and long-span, CFST with higher strength grades has also emerged as the times require. In order to give full play to the mechanical advantages of the combined components of high-strength concrete and steel pipes, an expansion agent is added to the concrete to prepare high-strength self-stressing steel pipe concrete, which can achieve the purpose of tightly integrating with steel pipes, preventing debonding and voiding, and improving bearing capacity. At present, various CFST expansion agents cannot meet the performance requireme...

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Problems solved by technology

At present, various CFST expansion agents cannot meet the performance requirements of high-strength self-stressed CFST, and there are many problems: (1) With the development of CFST to high strength and large diameter, the shrinkage of concrete increases, so higher High-efficiency expansion agents with expansion performance can achieve the purpose of compensating for concrete shrinkage, preventing hollowing and debonding of steel pipes, and improving bearing capacity; (2) Currently, more sulphoaluminates, calcium oxides and composite expansion agents are used The early hydration and expansion speed are fast, but the expansion performance is unstable in the long-term age, and the later shrinkage increases, which cannot compensate for the later shrinkage of concrete; (3) The expansion of ordinary expansion agents is uncontrollable, and it is difficult to achieve the coordinated development of expansion performance and strength , due to the rapid strength development of high-strength concrete, the expansion reaction starts earlier and the expansion energy is larger in the early stage, and the expansion performance in the later stage is stable to ensure that the components do not debond, and the mechanical properties are stable; The water consumption of concrete is low and the shrinkage is large, so the hydration reaction of the expansion agent is easily affected by the low water consumption and it is difficult to achieve high expansion efficiency; (5) Under the closed condition of the steel pipe, the concrete maintenance is difficult, and it is difficult to provide concrete and expansion agent The water supply required for hydration, therefore, curing technology has also become the key to restrict the expansion performance of high-strength self-stressed concrete

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