The reason for freezing damage to panels during highway cement concrete pavement construction is mainly due to the condensation and solidification of a large amount of moisture inside them in winter. The phenomenon is serious and the required hardening strength cannot be reached, resulting in damage to the pavement panel. To reduce the risk of freezing damage, construction in winter should be avoided as much as possible. But often due to various reasons, such as in order to meet the construction deadline, construction must be done in winter. In addition to selecting high-quality cement, sand and gravel and other materials, insulation work must also be done. Not only should we pay attention to thermal insulation during material stacking and transportation, but we must also take necessary thermal insulation measures during construction and mixing. After the construction is completed, the concrete surface must be insulated and maintained. Only in this way can the impact of freezing damage during winter construction be minimized. .
1. Insulation of sand and gravel materials
The sand and gravel used must be strictly Quality assurance, and reasonable anti-freezing measures should be taken during winter construction. First of all, thermal insulation of sand and gravel materials stacked in the open air can reduce heat loss when the sand and gravel materials are stored. Generally, the sand and gravel materials are covered with insulation materials, such as wool, plastic film, straw mats, etc., to ensure that the sand and gravel materials can reach the temperature required for construction. Secondly, for sand and gravel materials stacked indoors, it is necessary to ensure their sealing to reduce heat loss and prevent the intrusion of outdoor cold air. Because the intrusion of cold air will speed up the cooling of the sand and gravel materials, indoor heating method can usually be used to ensure the temperature of the sand and gravel materials.
2. Raise the temperature of the water when mixing in the machine
During the formation process of concrete , it is necessary to add water for stirring. The temperature of the water should be increased appropriately, which can effectively reduce the occurrence of freezing damage. In addition, it is necessary to ensure that the sand and gravel materials are fully and evenly heated during the mixing process, ensure the temperature of the machine, and increase the hydration speed, thereby ensuring that the concrete pavement is stronger and reducing the possibility of pavement collapse.
3. Reduce water consumption during mixing
When laying concrete pavement in winter, the water temperature Appropriateness is only one of the key points, and what cannot be ignored is that the amount of water used for mixing concrete should be appropriate or even appropriately reduced. In this way, when paving the road, due to the reduction of water in the concrete, the solidification of water can be avoided, further preventing freezing. crack. Moreover, as the proportion of water glue in concrete decreases, the concentration of liquid phase ions can be increased, reducing the chance of being frozen and improving the frost resistance of concrete.
4. Use antifreeze
In winter, the climate is cold and the temperature is low, and concrete is easy to Freezing damage occurs. Therefore, the use of antifreeze in road construction can enhance the ability of concrete to withstand cold and ensure the stability of its chemical properties. At the same time, it can accelerate the setting and solidification of concrete and improve its durability. However, concrete antifreeze needs to comply with relevant usage requirements and be reasonably selected according to local temperature conditions to ensure normal hydration under negative temperatures.
5. Extend the mixing time
When the mixer is mixing sand and gravel materials, it is necessary to Stir the mixture inside thoroughly. In winter, the mixing time needs to be extended. The mixing time of these concretes containing admixtures is usually more than double that at room temperature. This method of extending the mixing time can effectively shorten the difficulty of construction. If you just stir according to the previous mixing time, some of the admixtures will be heated unevenly and cannot be fully dissolved, thus affecting the strength of the concrete.
6. Use the greenhouse method to prevent freezing of concrete pavement
Concrete pavement in winter During construction, a greenhouse can be set up for the paved road. The specific method is to build a half-meter-high greenhouse-like facility above the road surface and cover it with a layer of plastic or straw mats for insulation. This insulation facility must be easy to disassemble and assemble so that it can be moved and reused in a timely manner. In addition, a warm shed can also be set up when watering. When the on-site mixer is mixing sand and gravel materials, a warm shed can also be set up above the mixer to reduce the impact of cold air and help achieve a certain temperature during mixing.
7. Surface insulation through heat storage method
The heat storage method is to insulate concrete After the construction is completed, insulation is carried out by covering it with a layer of insulation material. This is a new insulation measure that has been recently adopted. Covering the road with a layer of quilt can reduce freezing damage caused by low temperatures and prevent the concrete from deteriorating. Cracks appear on the surface. This method is convenient, simple and conducive to construction. Moreover, the temperature difference between the inside and outside can be greatly reduced so that the concrete can solidify and harden normally.
In short, although the construction technology of today's concrete pavement has been greatly improved and improved compared with the previous manual pouring. But after all, during winter construction, freezing damage is easily caused due to the complex climate. Therefore, it is necessary to take necessary construction insulation measures, that is, to insulate the sand and gravel materials, increase the temperature of the water when mixing in the machine, reduce the water consumption during mixing, use antifreeze, and extend the mixing time.Only by adding thermal insulation and anti-freezing facilities to the finished product can we ensure that the quality of the poured cement concrete pavement meets the specification requirements.
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