A Calculation Method of Surface Area Mix Ratio of Sand-free Concrete

Abstract

The invention discloses a method for calculating the mix proportion of the surface area of the non-sand concrete. The method comprises the following steps: firstly, extracting N samples, carrying out three-axial length measurement on aggregate particles in an orthogonal direction so as to obtain an axial length proportion mean value, and establishing an ellipsoidal model; secondly, introducing a representative axial length radius as an axial length radius of a whole aggregate; thirdly, estimating the number of the aggregate particles contained in a unit area of the aggregate, and determining slurry warping thickness; and finally, calculating the mix proportion of the surface area of the concrete. According to the method, the property of the aggregate is adequately considered, and a new spheroid aggregate calculation model is disclosed based on the property and is accordant with actual conditions; meanwhile, an error between a correction factor shrinkage estimated value and an actual value is presented in the aggregate number estimation; the total demand of cement paste can be calculated under a specific condition, so that the paste settling phenomenon caused by overmuch cement paste is avoided, the unnecessary wasting is reduced, and meanwhile, the condition of relatively low strength, caused by the deficiency of the cement paste, of a concrete product is avoided.

Description

technical field [0001] The invention relates to a method for calculating the mix ratio of concrete, in particular to a method for calculating the mix ratio of the surface area of ​​sand-free concrete. Background technique [0002] Sand-free concrete is made by mixing coarse aggregate and cement slurry. The cement slurry mainly plays the role of cementing coarse aggregate. Since it does not contain or contains less fine aggregate, sand-free concrete has greater porosity and air permeability. and water permeability; due to the special structure of sand-free concrete, its strength mainly comes from the cement paste bonded body on the aggregate bonding surface; therefore, the bonding area between aggregates becomes an important indicator for controlling the strength of sand-free concrete, and the unit volume is different The difference in the total surface area of ​​particle size aggregates has become an important factor to be considered in the mix design; and the mix design sch...

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Problems solved by technology

[0002] Sand-free concrete is made by mixing coarse aggregate and cement slurry. The cement slurry mainly plays the role of cementing coarse aggregate. Since it does not contain or contains less fine aggregate, sand-free concrete has greater porosity and air permeability. and water permeability; due to the special structure of sand-free concrete, its strength mainly comes from the cement paste bonded body on the aggregate bonding surface; therefore, the bonding area between aggregates becomes an important indicator for controlling the strength of sand-free concrete, and the unit volume is different The difference in the total surface area of ​​particle size aggregates has become an important factor to be considered in the mix design; and the mix design scheme for sand-free concrete introduced in the widely used "Modern Concrete Mix Design Manual" is not The impact of aggregate particle size and different particle size grouting thickness on sand-free concrete is not considered; for aggregates with different particle sizes per unit volume, the total surface area of ​​aggregates is different, and large particle size aggregates per unit volume The total surface area is small, and the total surface area of ​​small particle size aggregate is larger; for the amount of cement slurry designed according to the "Modern Concrete Mix Design Manual" of unit volume aggregate, the unit volume of larger particle size aggregate is more important for cement slurry. If the demand is small, it is easy to produce sinking phenomenon at this time; the existence of sinking not only wastes cement but also greatly reduces the porosity of concrete, which seriously affects the water permeability and air permeability of sand-free concrete; on the other hand, the unit volume is relatively small The total surface area of ​​small-sized aggregates is large, and the demand for cement slurry is also greater. Insufficient cement slurry will lead to uneven grouting on the surface of aggregates, which will seriously affect the strength of sand-free concrete and endanger engineering safety.

[0003] The existing sand-free concrete surface area mix ratio design method simplifies the aggregate directly into a sphere in the simplification of the aggregate model, and regards the lengths of each radial direction as a uniform value. Such oversimplification makes the hypothetical model and the actual aggregate shape The deviation is far, and the use of the ellipsoid model can accurately reflect the size of the aggregate sample in three orthogonal directions, which is more in line with the actual situation; on the other hand, in the calculation of the total surface area of ​​the aggregate, the existing surface area design method There is no control condition between the model and the actual aggregate, which will cause the model to not accurately represent the aggregate surface area; at the same time, in the estimation of the number of aggregates per unit volume, the total mass of the aggregate is divided by the mass of a single model aggregate The method does not take into account the difference between the actual value (the measured value of aggregate mass per unit volume) and the representative value (the mass of a single aggregate model)

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