A low-shrinkage, crack-resistant C60 grade self-compacting bridge tower concrete based on internal curing, shrinkage compensation and toughening and its preparation method

Abstract

The present invention discloses a low shrinkage anti-cracking C60 grade self-compacting bridge tower concrete based on internal curing, shrinkage compensating and toughening, wherein the low shrinkage anti-cracking C60 grade self-compacting bridge tower concrete is prepared from the following raw materials: cement, fly ash, mine powder, an expander, an AN-ICA internal curing agent, crushed stone, river sand, polyacrylonitrile fibers, micro-scale modified degreasing cotton cellulose, a cement slurry microstructure regulation agent, water and an ultra-dispersed water-reducing and shrinkage-reducing superplastic admixture. According to the present invention, the initial slump is more than or equal to 230 mm, the expansion degree is more than or equal to 630 mm, the 28 d compressive strength is more than or equal to 70 MPa, the 28 d splitting tensile strength is more than or equal to 5.8 MPa, the toughness index I5 is more than or equal to 3.0, the 28 d self-shrinkage is less than 100*10<-6>, the 28 d dry shrinkage rate is less than 150*10<-6>, the carbonization grade achieves T-IV, the anti-cracking grade achieves L-V, the product has characteristics of excellent mechanical property, excellent cracking resistance and excellent durability, and the difficult problems of high cement and cementing material material consumption, large shrinkage and easy cracking of the bridge tower concrete at the current stage can be solved.

Description

technical field [0001] The invention belongs to the field of building materials, and in particular relates to a low-shrinkage, crack-resistant C60 grade self-compacting bridge tower concrete based on internal curing, shrinkage compensation and toughening and a preparation method thereof. Background technique [0002] Cable-stayed bridges are being used more and more widely because of their elegant shape, super-large span, super-navigable capability and light structure. The bridge tower is the main load-bearing structure of the cable-stayed bridge, which bears the huge cable force brought by the bridge, and its mechanical properties and durability determine the service life of the entire bridge. However, super-high bridge towers have dense reinforcement, large height, and large cross-sectional size, requiring the bridge tower concrete to have high flow performance, low temperature rise, and high volume stability. [0003] However, the high-performance concrete of bridge towe...

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Problems solved by technology

[0003] However, the high-performance concrete of bridge towers used at present generally has the following problems: (1) the admixture used has limited dispersion ability to cement, and about 10% of the cement particles in the concrete have not been fully hydrated and only play the role of inert filling. Therefore, the amount of cement and cementitious materials in bridge tower concrete is generally high, the concrete has a large adiabatic temperature rise, large shrinkage, and is easy to crack; (2) adding expansion agent to high-strength concrete to compensate for shrinkage, due to the concrete water-cement ratio Low, there is not enough water for the expansion agent to react in the later stage of hydration, and its expansion performance is difficult to exert, and the due shrinkage compensation effect cannot be achieved; (3) Internal curing materials represented by SAP are more sensitive to the pH value of the solution, After the pH value of the solution rises, the water will be released rapidly in a short time, which will affect the working performance and mechanical properties of the concrete; (4) the structural characteristics and service environment of the bridge tower require the bridge tower concrete to have good crack resistance and durability. At present, the commonly used anti-cracking measure is fiber crack resistance. However, ordinary admixtures have limited effect on reducing viscosity and maintaining plasticity of concrete. After adding fibers to high-strength concrete with low water-binder ratio, it will seriously affect the working performance of concrete, which is difficult to achieve. Its self-compacting and ultra-elevation pumping

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