干缩裂缝多出现在混凝土养护结束后的一段时间或是混凝土浇筑完毕后的一周左

Shrinkage cracks mostly appear in a period of time after the completion of concrete curing or about a week after the completion of concrete pouring. The evaporation of water in the cement slurry will produce dry shrinkage, and this shrinkage is irreversible. The occurrence of shrinkage cracks is mainly due to the difference in the degree of moisture evaporation inside and outside the concrete, which results in different deformations: the concrete is affected by external conditions, the surface moisture loss is too fast, the deformation is large, the internal humidity change is small, the deformation is small, and the deformation is large. The surface shrinkage deformation is restrained by the concrete, resulting in large tensile stress and cracks. The lower the relative humidity, the greater the shrinkage of the cement paste, and the easier it is to produce shrinkage cracks. Shrinkage cracks are mostly superficial parallel linear or net-like shallow cracks, with a width between 0.05 and 0.2 mm. They are more common in the plane parts of large-volume concrete, and are distributed along the short direction in thinner beams and slabs. Shrinkage cracks usually affect the impermeability of concrete, cause the corrosion of steel bars and affect the durability of concrete, and under the action of water pressure, hydraulic fracturing will affect the bearing capacity of concrete and so on. The shrinkage of concrete is mainly related to the water-cement ratio of concrete, the composition of cement, the amount of cement, <br>the nature and amount of aggregate , and the amount of admixtures.

Dry shrinkage cracks often appear in a period of time after the completion of concrete curing or about a week after the completion of concrete pouring. The evaporation of water in cement slurry will produce dry shrinkage, and this shrinkage is irreversible. The occurrence of dry shrinkage crack is mainly due to the different deformation caused by the different degree of water evaporation inside and outside the concrete: the concrete is affected by external conditions, the surface water loss is too fast, the deformation is large, the internal humidity change is small, the deformation is small, and the large surface dry shrinkage deformation is constrained by the internal constraints of the concrete, resulting in large tensile stress and cracks. The lower the relative humidity, the greater the dry shrinkage of cement paste, and the easier it is to produce dry shrinkage cracks. Dry shrinkage cracks are mostly surface parallel linear or network shallow and fine cracks, with a width of 0.05 ~ 0.2mm. They are common in the plane of mass concrete, and they are mostly distributed along the short direction in thinner beams and slabs. Dry shrinkage cracks usually affect the impermeability of concrete, cause the corrosion of reinforcement, affect the durability of concrete, produce hydraulic splitting under the action of water pressure, affect the bearing capacity of concrete and so on. The dry shrinkage of concrete is mainly related to the water cement ratio of concrete, the composition of cement, the amount of cement and aggregate<br>Properties of the are related to dosage, dosage of the admixture, etc.

Shrinkage cracks often appear in a period of time after concrete curing or about a week after concrete pouring. Evaporation of water in cement slurry will produce dry shrinkage, and this shrinkage is irreversible. Dry shrinkage cracks are mainly caused by different degrees of moisture evaporation inside and outside the concrete, resulting in different deformations: due to the influence of external conditions, the concrete loses too much moisture on the surface, and the deformation is large, while the change of internal humidity is small and the deformation is small, and the large surface dry shrinkage deformation is constrained by the inside of the concrete, resulting in large tensile stress and cracks. The lower the relative humidity, the greater the shrinkage of cement paste, and the easier it is to produce shrinkage cracks. Dry shrinkage cracks are mostly superficial parallel lines or reticulate shallow fine cracks, the width of which is mostly between 0.05 and 0.2 mm, the plane parts of mass concrete are more common, and the thin beams and slabs are mostly distributed along its short direction. Dry shrinkage cracks usually affect the impermeability of concrete, cause corrosion of steel bars to affect the durability of concrete, and hydraulic fracturing will occur under the action of water pressure to affect the bearing capacity of concrete and so on. Dry shrinkage of concrete mainly depends on the water-cement ratio of concrete, the composition of cement, the dosage of cement and aggregate. The nature and dosage, the dosage of admixture, etc.