The size of water cement ratio can act on the strength of concrete quickly, and can also cause dry shrinkage cracks.
In this process, due to obvious dry and wet deformation, chemical shrinkage and temperature deformation, the strength of the concrete is low, so it is easy to have concrete cracks.
The shrinkage amount in this link can not be underestimated.
The high temperature in summer makes the water easy to evaporate.
When there is more water, the dry shrinkage of concrete will be greater; With more cement, the plasticity can be greatly deformed.
(1) temperature change.
2.2 increase the relative humidity of the air.
(1) delamination of cement concrete stacking structure.
The phenomenon of “false condensation” and too early condensation makes the cracks in the early stage occur.
Generally speaking, only when the cement concrete block hardens without shrinkage, the implementation of joint cutting treatment can comprehensively prevent the occurrence of cracks.
Water is an essential substance for hydration reaction.
(2) hydration reaction of cement.
In summer, under the action of sunshine exposure or dry hot wind and other factors, the temperature of sand and stone can reach the range of 60 to 70 ℃, while the temperature of mixed concrete can reach the high temperature of about 40 ℃.
When this reaction is carried out, the concrete can undergo the second heating and cooling, so the volume of concrete can undergo repeated secondary expansion and shrinkage deformation at the same time.
On the basis of timely curing, let the concrete have more water outside, which can comprehensively avoid the occurrence of evaporation, reduce the shrinkage and ensure that the external hydration of concrete can be carried out in an orderly manner.
If the curing is not in place, the concrete can be “burned”, and the water outside the concrete will be evaporated in the shortest time, causing dry shrinkage cracks.
In the process of pouring and tamping cement concrete, certain delamination problems can occur.
For the newly poured concrete using a series of curing, the curing measures shall be taken after the external shaping of the concrete and the external water film does not disappear.
When mixing, vibrating, setting, hardening and other links are carried out, cement and water can undergo hydration reaction.
Once the concrete body is not limited by any factors, the expansion and contraction deformation can occur casually.
There is a lot of mud content in the aggregate, and there are many particles forming the mud film outside the aggregate, which can reduce the cementation between the aggregate and cement and improve the thinner position in the concrete.
Due to the theory of thermal expansion and cold shrinkage, with high temperature, the concrete poured during the day and in the middle of the night will have volume shrinkage, that is, temperature deformation, at the lowest temperature the next morning.
(2) influence of seam cutting process.
At the same time, it will also cause cracks, which will threaten the quality of the concrete structure.
Causes of concrete road cracks 1.1 internal causes.
The key significance of curing is to realize the whole step of hardening of concrete under suitable temperature and humidity conditions and improve the strength of concrete.
Therefore, it is necessary to select a proper scientific curing strategy and the best curing period.
(3) dry shrinkage reaction of cement concrete occurs.
On the contrary, the joint belongs to uneven burr.
Increasing the relative humidity of the air can comprehensively make the external water of the concrete evaporate less quickly.
In the upwind direction and around the newly poured concrete, choosing the way of spray fog to improve the relative humidity of the air is one of the appropriate methods that is not difficult to carry out.
However, the joint cutting process can only be carried out when the concrete achieves appropriate strength (about 5MPa ~ 10MPa).
Prevention measures for construction cracks of concrete roads in summer 2.1 select appropriate maintenance strategies and maintenance methods as soon as possible.
In the past, when the concrete with high temperature is paved and formed, it can be affected by sunlight radiation, and the temperature can rise sharply, resulting in “false setting” or premature setting, resulting in cracks in the concrete road.
Therefore, the newly poured concrete project is prone to rapid drying and rapid condensation, which reduces the strength.
If the batching is not accurate and there is no certain mixing, the concrete with disharmonious change in strength can be produced, so that the part with weak strength has dense stress, causing cracks in the concrete road.
1.2 external factors.
Because the concrete can be layered when it forms a stacking structure, this kind of delamination can make the concrete show greater strength from the outside to the inside.
Relevant studies show that when cement paste is constructed from cement slurry in cement concrete, only 3% volume deformation occurs in cement paste, which can lead to a tensile stress of 13Mpa on the interface between cement paste and aggregate.
Therefore, for the concrete road constructed in summer, certain prevention measures must be taken, especially in the mixing, transportation, pouring and maintenance of concrete.
The curing of cement concrete can effectively ensure the quality of concrete.
When the concrete is set and hardened, its internal tensile strength is not very high.
Because the tensile stress produced by cold shrinkage and dry shrinkage needs to exceed the tensile strength in this case as much as possible, there are cracks inside and outside the concrete.
(4) no reasonable concrete curing measures were taken.
Others can be evaporated, causing dry shrinkage deformation of concrete.
In other words, the external tensile capacity is not high, so it causes cracks in the concrete.
(3) uneven concrete mix proportion or insufficient mixing time.
Some special construction technical schemes must be applied to ensure the construction quality of concrete and make the quality meet the relevant construction specifications and design requirements.
However, during the curing, there shall be no pollution and damage to the formed external of the concrete.
In addition, the capital investment is not high..
The proportion of water in cement concrete accounts for 15% ~ 20% of the total weight of cement.
