Reasons for Cracks in the Use of River Slope Protection Bricks

With the increase of hydropower stations and water conservancy slope protection, the use of river slope protection bricks is becoming more and more frequent. After using molds to pour and form river slope protection bricks, some cracks will appear in the bricks after a period of use. Let's follow the editor to take a look.

The cracks generated during the pouring of river slope protection bricks are mainly due to the chemical reaction between cement and water during the hardening process of concrete, which generates a large amount of hydration heat and causes the temperature of the concrete to rise. If the heat cannot be quickly dissipated and the temperature difference between the inside and outside is too large, temperature stress will be generated, causing the structure to be compressed internally and pulled externally. In the early stage of hardening, concrete only has a very low tensile strength. If the tensile stress caused by the temperature difference between the inside and outside exceeds the early tensile strength of concrete, cracks will occur in the concrete.
The measures that can be avoided for such incidents are to choose low or medium heat cement to reduce slag and fly ash as much as possible; Reduce cement usage and keep cement below 450kg/m; Reduce the water cement ratio, and generally control the water cement ratio of concrete below 0.60; Improve the orthopedic grading of river slope protection bricks by adding fly ash or reducing water agents to reduce cement usage and lower hydration heat; Improve the mixing process of concrete and adopt the new technology of "secondary air cooling" to reduce the pouring temperature of concrete; Adding admixtures that reduce water, plasticize, and delay setting to improve the flowability and water retention of concrete mixtures, reduce hydrothermal activity, and delay the occurrence of thermal peaks; Reasonably arrange the construction process, pour in layers and blocks to facilitate heat dissipation, and set up cooling pipes inside the large volume concrete to reduce the internal temperature difference of the concrete through cold water or air cooling; Strengthen the monitoring of concrete temperature and take timely cooling protection measures; Strengthen concrete curing. After pouring concrete, timely cover it with damp grass curtains, hemp sheets, etc., and sprinkle water for curing. Properly extend the curing time of river slope protection bricks to ensure that the concrete cools slowly. In cold seasons, insulation measures need to be taken on both sides of the concrete to prevent cold tide attacks.
During use, some river slope protection bricks are used on some upstream surfaces, and the alternation of hot and cold water temperatures can easily cause cracks in cement products. Therefore, in order to reduce the occurrence of cracks, the cement used in the pouring process of the brick mold should have good frost resistance to avoid cracks in the bricks caused by the alternation of hot and cold, which can lead to damage to the river slope protection bricks and make it difficult to continue using.