A kind of self-compacting and non-shrinkage concrete used in the tube of long-span CFST arch bridge

Abstract

The invention discloses self-compacting non-contract concrete used in a large-span CFST (Concrete Filled Steel Tube) arch bridge tube. The self-compacting non-contract concrete used in the large-spanCFST arch bridge tube disclosed by the invention is prepared from the following components by weight: 350 to 450 kg / m<3> of cement, 100 to 200 kg / m<3> of mineral admixture, 750 to 850 kg / m<3> of fineaggregate, 900 to 1,000 kg / m<3> of coarse aggregate, 5 to 15 kg / m<3> of high-performance polycarboxylate water-reducing agent, 50 to 60 kg / m<3> of compound expanding agent, and 150 to 175 kg / m<3> of water. According to the self-compacting non-contract concrete used in the large-span CFST arch bridge tube, mechanical properties of the concrete are ensured through an optimal design of the mixing proportion of the concrete; the high-performance water-reducing agent which is compounded with the components with the functions of reducing water, retaining slump, delaying coagulation, defoaming, thixotropic modifying and the like is doped, so that the flowability of fresh concrete is improved; dense filling of the admixture in a steel tube is guaranteed; meanwhile, the thixotropy of the fresh concrete is enhanced, and a disengaging phenomenon at the upper part of the steel tube of a horizontal section of an arch crown is remarkably improved; the compound expanding agent is doped, so that the contraction deformation of the steel tube concrete is compensated in stages in the whole process; therefore, the concrete is closely adhered to the wall of the steel tube; the concrete and the steel tube are stressed cooperatively; a hoop effect is enhanced; the structural bearing capacity is guaranteed.

Description

technical field [0001] The invention relates to a self-compacting, non-shrinkage concrete used in a large-span CFST arch bridge pipe, with a design strength grade of C60, which has excellent work, mechanics and volume stability, can significantly improve the filling state of core concrete inside a steel pipe, and ensure structural bearing capacity and service life, especially suitable for large concrete filled steel tube bridges. Background technique [0002] Concrete-filled steel tube (CFST) arch bridge has the advantages of good mechanical properties, simple construction, enhanced ductility of core concrete, enhanced tensile and compressive strength, improved steel pipe instability performance and anti-rust ability, and convenient construction due to the combination of steel and concrete. Therefore, since my country built the first concrete-filled steel tube concrete road arch bridge—the Donghe Bridge in Wangcang County, Sichuan Province in 1991, the concrete-filled steel t...

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Problems solved by technology

For example, the incorporation of a strong dispersive water reducer can reduce the yield stress of the concrete mixture and increase the degree of expansion, but its plastic viscosity is still high at a low water-binder ratio, and the flow rate of the mixture is slow; adding a defoamer, It can reduce the air content of concrete to less than 2.0%, but a large number of engineering practices have shown that the high fluidity concrete with low air content still has the phenomenon of aggregation of small air bubbles for a long period of time after standing still, forming a large number of air bubbles with a span of 0.5mm-5mm Floating continuously, gathering at the top of the vault to cause voiding; adding aluminum powder to generate gas too quickly, and the hydrogen generated will bring the risk of hydrogen embrittlement damage to the steel structure; calcium expansion agent expands earlier, generally within 7 days Completing more than 90% of the entire expansion, the effect of compensating for the late shrinkage and deformation of steel pipe concrete is not good

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