Quality control of concrete construction in civil engineering?

Quality control of concrete construction in civil engineering is very important. Only by controlling the construction details and ensuring the construction quality can we achieve the expected effect and achieve the best. Zhong Da Consulting will explain the quality control of concrete construction in industrial and civil buildings.

At present, the most commonly used material in the construction process is concrete. Concrete is a building material, which is made by mixing water with aggregate, artificial stone and cementing material, vibrating and compacting, curing and hardening. Compared with other building materials, concrete has advantages in strength, corrosion resistance, plasticity and fire resistance, so it has been widely used. At the same time, in order to ensure the construction quality and safety, we must attach importance to the construction quality of concrete, and constantly develop new technologies and products to make them have better performance and more reliable quality, so as to improve the quality of buildings.

First, the problems existing in the construction

1. Raw materials

Different cement varieties have different setting and hardening time, and the compactness and corrosion resistance of cement stone structure are also different. It goes without saying that if the cement stone is damaged, the concrete will do. The three main factors of cement stone destruction are the high content of calcium hydroxide, the existence of calcium aluminate hydrate and the poor compactness of cement stone structure. According to the actual situation, choose suitable cement varieties for different water quality sandstone. In addition, the cement strength grade must be compatible with the concrete strength. If the cement strength is too high and the cement raw materials are not enough, the aggregate will inevitably be exposed, resulting in improper proportioning and separation of flesh and blood; If the cement strength is too low and there are too many cement raw materials, the redundant cement slurry will not only wrap sand and gravel, but also secrete slurry easily during vibrating. Therefore, it is more important to choose the appropriate cement strength according to the engineering requirements in building engineering.

2. The mixture ratio of concrete is not in conformity with the regulations.

The pouring effect of concrete in construction partly depends on the mix proportion of concrete. When mixing concrete, the imbalance of cement, sand and water will lead to different concrete grades, which will not meet the design standards of concrete grades, and then affect the strength of concrete after mixing. Such concrete will cause serious quality and safety problems after pouring.

3. Honeycomb

The quality of honeycomb is worse than that of pockmarked surface. The main difference is that the holes in the pits are produced on the surface and do not affect the quality inside. However, the honeycomb not only has uneven surface, but also has holes and gaps inside, which is named because these holes are similar to the honeycomb. Honeycomb phenomenon is most likely due to the measurement error of cement materials or inaccurate water measurement, inappropriate concrete mix ratio, too many mortar stones, lax vibration, improper blanking or unstable formwork, which leads to slurry leakage and eventually forms honeycombs. Another situation is that the concrete is not ready for construction, and the concrete is mixed with large sundries, and it is not operated according to the construction technology, which leads to the unsmooth pouring of concrete into the formwork, resulting in large bubbles, which can not completely fill the gaps between the formwork, resulting in holes in the finished product.

Second, the construction quality control strategy

1. Selection of raw materials

Some factors that affect the durability of concrete are raw materials. Therefore, when improving the durability of concrete, it is necessary to strengthen the selection of concrete raw materials. The strength and performance of cement are formed during the solidification and hardening of cement mortar. If cement is destroyed in this process, the durability of concrete will be reduced. Therefore, when selecting cement raw materials, we should strengthen the investigation of cement varieties and test the quality of cement. Cement with low alkali content, small drying shrinkage, good heat resistance, water resistance and corrosion resistance should be selected, and combined with the actual situation. In addition, in the process of cement selection, not only the strength of cement can be used as the selection standard, but also low-standard cement can be used to prepare high-standard concrete. Therefore, in the process of selecting cement, the strength and performance of cement should be considered at the same time.

2. Control the proportion of raw materials

Proportion of concrete components. To ensure the quality of concrete, not only must there be high-quality raw materials, but also the mixture ratio of various raw materials should meet certain requirements. Among them, the proportion of ash and water is very important, and it should be strictly in accordance with the formula requirements and combined with the building environment. In the actual construction process, it can also be modified after strict calculation and verification. For example, adjust the proportion according to the actual water content of sand and gravel on the construction site. No matter how to adjust, its ultimate goal is to ensure the best working performance of concrete. According to China's requirements for building construction concrete, its strength should be C20~C50. Therefore, in the process of building construction, it is necessary to ensure that the actual raw material ratio of concrete meets the actual demand and the relevant provisions of the state. Before concrete processing, it is necessary to strictly examine whether the formula is suitable and meets the local climate requirements.

3. Prevent concrete carbonization reaction

The carbonation of concrete is mainly due to the chemical reaction between Ca(OH)2 in cement and CO2 in the air under the action of steam, resulting in CaCO3 and H2O. Carbonization of concrete will lead to the intensification of concrete shrinkage, and slight cracks will occur in concrete volume due to shrinkage stress, which will lead to the decline of concrete strength and impermeability. In order to prevent this, high-strength concrete or high-grade high-strength cement can be used. When the compressive strength of concrete reaches a certain limit, the carbonation of concrete will not affect the durability of concrete. At the same time, high-pressure steam can be used to strengthen the curing of concrete, ensure the compactness of concrete, enhance the durability of concrete and improve the carbonation resistance of concrete. The corrosion of reinforced concrete is mainly due to the carbonation of concrete, which reduces the alkalinity of concrete, leads to the corrosion of steel bar surface without good protection, and leads to the decrease of concrete durability. The main preventive measures are: coating epoxy resin on the surface of reinforced concrete to avoid corrosion of unprotected steel bars; Under the condition of ensuring the concrete mixture ratio, additives can be added appropriately to improve the compactness and durability of concrete.

4. Improve impermeability

Impermeability refers to the difficulty of fluid passing through its interior under different pressures. Concrete is a composite material formed by a large number of colloids and crystals generated by cement hydration reaction. There are glue holes, capillary holes and cavities in the material. If the three are connected to form a continuous form, the impermeability of porous materials will become worse. In order to improve the impermeability of concrete, it is necessary to offset the shrinkage of concrete when it hardens, so expansive agent is added. The micro-expansion effect produced by hydration of expansive agent is used to offset the self-shrinkage of concrete during hardening and improve the impermeability of concrete. However, the concrete prepared with new high-performance polycarboxylic acid admixture has low shrinkage and good water retention, so the probability of microcracks and cracks is very low, which is beneficial to improve the impermeability of concrete.

Third, the conclusion

The quality of buildings is very important for the safety of people living in them. If the operation process is not strictly monitored and the materials of various parts of concrete are not restricted, it may cause extremely serious quality problems, from property loss to life safety. Therefore, the quality control of concrete construction must be strictly controlled, and the links and steps that are prone to quality problems must be strictly guarded to fundamentally ensure that the quality of concrete construction meets the requirements.

For more detailed information about "Quality Control of Concrete Construction in Industrial and Civil Buildings", Zhong Da's consultation and construction link is simple, convenient and reliable.

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