About cutting joints
- Cement concrete pavement reaches more than 25% of the design strength when cutting joints, generally in order not to destroy the principle of concrete, the next day in summer can be cut. According to the temperature of the day of pouring, such as 35 ℃, can be cut within 10h-12h. Subject to the principle of no collapse and no cracks, try to lean forward.
- Cutting joints must be cut only after demolition of the mold. Demolition of the edge mold has strength requirements, because demolition of the mold will have vibration, so demolition of the mold requires a strength of 25%, which is a basic requirement for cutting joints.
- According to the sand rate of concrete, pavement concrete surface layer is mostly mortar, if the time to cut joints early, machinery walking on it or people working on it is easy to damage the overall surface of the pavement and the construction factor.
- Cement concrete pavement cutting time should generally be carried out about 12 hours after the demoulding of concrete, the best cutting time is mainly affected by the strength of the concrete, that is, to meet the best strength requirements of the cutting machine cutting concrete. Cutting time early, the cement concrete strength is not enough to meet the cutting strength requirements, easy to produce the phenomenon of missing edges and corners off damage; cutting time too late the temperature stress can not be released in time, when the temperature stress exceeds the concrete flexural strength will occur when the broken plate, so the choice of the best cutting time is mainly determined by the cement concrete strength growth law with time.
Additives and water
The specific surface area of coarse and fine aggregates determine their own water absorption rate, the thirst for water is physical water absorption, while the admixture is relying on the chemical reaction with the cementitious material (surface water-repellent groups) to achieve the concrete state, the role of water is the admixture can not replace. How to see the cement high alkali lack of sulfur ah? There is no direct and effective method, if you suspect that the high alkali lack of sulfur try to use sodium thiosulfate, if it works, no effect on the abandonment. If the net slurry experiment or trial loss is not normal fast, you will consider various factors, and then one by one to rule out. Cement problems are also common, especially during the change of season.
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