Cement-based composite and mending method of concrete cracks

Abstract

The invention discloses a cement-based composite and a mending method of concrete cracks. The cement-based composite is prepared from the following components in parts: 15 to 69 parts of cement, 17 to 30 parts of water, 10 to 45 parts of refined aggregate, 34 to 104 parts of fly ash, 0 to 4.5 parts of silica ash, 0 to 8 parts of granulated blast-furnace slag, and organic fiber of which the volume is 1.5% to 2.5% of the total volume of the composite. Therefore, the cement-based composite not only has the function of the conventional cracked cement composite, but also can prevent steel bars inside the concrete from rusting. The mending method of the concrete cracks not only pays attention to reduce stress generated on a contact part between a mending layer and concrete cracks, but also pays attention to enhance the bonding strength of the mending layer and peripheral rims of the concrete cracks; besides, the water in the mending layer is prevented from infiltrating into the cracks to cause the rusting of the steel bars inside the cracks through the injecting epoxy material in the cracks, and a waterproof layer is adopted to prevent the water and the oxygen from entering into the cracks through the mending layer.

Description

technical field [0001] The invention relates to the field of building materials, in particular to a cement-based composite material and a method for repairing concrete cracks. Background technique [0002] Cement concrete is one of the largest and most widely used building materials in the world, such as reinforced concrete bridges, which are currently an important structural form of bridges. However, cement concrete materials have some defects, such as heavy weight, low tensile strength, and easy shrinkage cracking (including plastic shrinkage cracking, hardening drying shrinkage cracking), etc. These defects limit its wider use in structural engineering. Among them, the defect that cement concrete is prone to drying shrinkage cracking (including plastic shrinkage cracking and hardening drying shrinkage cracking) has a great impact on the quality of concrete, especially for high-strength concrete. [0003] The hazards of concrete cracking are as follows: 1. Overa...

AI Technical Summary

Problems solved by technology

Although this method is better and practical, it does not give too much consideration to the cracking effect of the steel bars in the concrete on the cracks. Under normal circumstances, the steel bars in the reinforced concrete are wrapped in the concrete protective layer. With the presence of calcium hydroxide, potassium hydroxide, and sodium hydroxide, the pH value of concrete is generally greater than 12. In such an alkaline environment, an iron hydroxide passivation film will be formed on the surface of the steel bar to protect the steel bar from corrosion

However, when the pH value of the environment drops to 9 or 8, the passivation film of the steel bar will lose its stability or even be destroyed, especially in the case of concrete cracking. , the steel bar is corroded, and the surface generates rust, that is, Fe 2 o 3 ·xH 2 O, the rust is loose and cannot block air or water, so that the steel bar will continue to rust

When the steel bar is corroded, it will produce 2-4 times the volume expansion, causing the surrounding concrete protective layer to be cracked or even fall off, which will affect the normal function and use of the structure. If there are cracks in the concrete, the corrosion of the steel bar will aggravate the cracks. , thus causing the original cracks to develop into penetrating main cracks, affecting the building structure itself

Once this kind of internal steel bar corrosion occurs, only painting the multi-cracked cement-based composite material on the outside cannot prevent the corrosion of the steel bar, because the multi-cracked cement-based composite material itself is easy to form tiny multi-slits, which cannot prevent the corrosion of the air. , oxygen permeates into

Moreover, this method of only relying on casting a repair layer around the crack to disperse the stress when the interface crack expands and delays the crack embedding into the repair material, for cracks with a large width or a large tensile load, the repair effect is weak , needs to be further improved on this technology to adapt to the repair of various cracks

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