Construction method for densifying surface layer of middle/low-strength concrete

Abstract

The invention discloses a construction method for densifying the surface layer of middle / low-strength concrete, which relates to the technical field of concrete construction. The middle / low-strength concrete is poured by a concrete temperature and humidity preservation maintenance template which is disclosed in a patent with the patent number of 2009200384330. The mixing proportion of the middle / low-strength concrete is optimized, the using amount of a gelatinization material and the using amount of water are controlled, the ratio of the water to the gelatinization material is also controlled, and the early-stage maintenance of the concrete is enhanced, so the ratio of the water to the gelatinization material of the concrete of the surface layer can be maximally reduced, the compactness and durability of the concrete can be improved, the surface layer densifying degree of the middle / low-strength concrete can be improved, the generation of temperature shrinkage cracks of the concrete can be prevented and the full development of the strength of the concrete is ensured.

Description

technical field [0001] The invention relates to the technical field of concrete construction, in particular to a construction method for improving the compactness of concrete in a reinforced protective layer of a concrete structure with medium and low strength grades (that is, C20-C35). Background technique [0002] Concrete is the most widely used building material in modern times. In addition to meeting the mechanical performance indicators required by engineering design, concrete should also have good durability to meet the safety and service life requirements of the project. However, many engineering cases show that the poor durability of concrete in the service period has been far greater than the design life attenuation, showing common quality defects, and even causing quality accidents and causing serious economic losses. According to statistics, the annual cost of repairing and rebuilding concrete projects in the world has reached tens of billions of dollars, and mor...

AI Technical Summary

Problems solved by technology

[0003] At this stage, a large number of C20-C35 medium and low-strength grade concrete is used in my country, and the water consumption of concrete with a slump greater than 10cm is basically 175-200kg / m 3 The water-binder ratio of concrete is between 0.4 and 0.55, the water consumption of concrete mixing is large, and the water-binder ratio is relatively high; in the process of concrete pouring and vibration, the fine particles in cement, water and aggregate are easy to get close Formwork or horizontal surface aggregates, resulting in high water content in the surface concrete, and the water-binder ratio is greater than that of the internal concrete; the particle gradation of the cementitious material is unreasonable, and the pores in the cement stone are not filled with ultra-fine particles; the early maintenance of concrete is not an important construction process. Concrete lacks a good early maintenance method; thus, during the early strength growth process of concrete, as the water in the concrete evaporates, many pores are formed in the concrete, and the concrete pore structure is unreasonable

Experimental research shows that there are many harmful pores or harmful pores with a pore size greater than 100nm, while the harmless pores and less harmful pores less than 100nm are relatively few. The permeability of the surface concrete is high, which is conducive to the intrusion of corrosive media, and the durability of concrete is poor.