Double Head Lifting Pin Anchor
(2) the reinforcement entering the site shall be stacked neatly and covered with plastic cloth for protection when it rains.
As high temperature will reduce the air content, the amount of air entraining agent should be increased.
4.
At the same time, the particle size of aggregate shall be increased if the pouring conditions permit.
Under dry conditions, the concrete poured at night is relatively less affected by wind and temperature.
(5) When transporting concrete for a long distance in the season of high temperature and humidity, the delayed mixing of the transportation mixer can be considered to make it still in the mixing state when it arrives at the construction site.
Construction measures in rainy season: 1.
In case of rain during concrete pouring, measures shall be taken immediately to cover it with plastic cloth to prevent the newly poured concrete from being washed by rain.
Construction site: form a good drainage system for the construction site and living area according to the terrain to ensure smooth water flow and no ponding.
Because the higher temperature accelerates the setting, the transportation of concrete will become more difficult.
Treatment measures: (1) spray water on the aggregate pile to cool the aggregate through the evaporation of water; (2) Adding retarder into concrete; (3) Replace part of the mixed water with ice if necessary; (4) Adding fly ash to adjust the influence of hot climate; (5) Appropriately increase the amount of cement per cubic meter of concrete.
Reinforcement works: (1) the reinforcement processing site should be well protected against rain and drainage.
(6) When possible, plans should be made to avoid placing concrete at the highest daily temperature.
(3) If higher slump is required, superplasticizer should be used.
The weather forecast shall be known in time before concrete pouring, and the construction shall be organized in sunny days as far as possible.
If the concrete needs air entrainment, the high temperature will make the air content more difficult to control.
(2) due to the use of commercial concrete, the commercial concrete mixing plant is required to adjust the construction mix proportion according to the moisture content of sand and stone before opening, and strictly control the slump of commercial concrete to meet the construction requirements in rainy seasons.
2.
Measures in the process of concrete mixing, transportation and unloading measures should be taken to control the temperature of concrete during concrete mixing, control the additional water volume by controlling the temperature of concrete, reduce the rate of slump loss, and reduce plastic shrinkage cracking.
(3) when the concrete does not reach the initial setting, in case of rain, it should be covered with plastic cloth in time to prevent rain..
At this stage, the following measures can be taken: (1) reduce the amount of cement by using water reducer or replacing cement with fly ash.
It is forbidden to pour concrete in heavy rain.
3.
The raw materials and processed reinforcement should be covered with plastic cloth to prevent rain from rusting the reinforcement.
There are mainly: (1) the durability of hardened concrete becomes worse; (2) The workability of concrete mixture is reduced; (3) The mixing amount is reduced.
1.
(7) In addition to adding mixing water according to the design quantity to adjust the specified slump, no additional mixing water shall be added on the construction site.
Superplasticizer can also reduce the friction between aggregate particles in the mixing process and slow down the heat accumulation in the mixing drum of the transportation mixer.
During construction, the construction flow schedule of reinforcement works shall be well organized, and the construction shall be carried out in rainy weather as far as possible.
The early strength of concrete cured at higher temperature increases rapidly, but the strength that may be reached at 28 days will be reduced accordingly.
All reinforcement stacking sites should be hardened with fine aggregate concrete, and the reinforcement should be placed at 250mm × On the 300mm concrete pier, prevent the reinforcement from being soaked by ponding and polluted by soil.
Through careful selection of raw materials and construction methods for concrete preparation, some adverse effects can also be reduced.
Adverse effect of hot climate on concrete when the temperature of concrete rises, the water consumption of concrete should be increased in order to maintain the slump required for pouring operation.
At the same time, the temperature rises, and the slump loss rate of the concrete mixture accelerates, so that sometimes when the concrete is transported from the mixing plant to the construction site, it is necessary to add water to the concrete mixture again.
If the concrete must be poured due to the rush of the project, the measures of canopy covering shall be taken.
It is necessary to correctly analyze the causes of adverse factors, and then take effective technical measures to eliminate or minimize adverse factors.
Because the newly poured concrete may have adverse effects such as accelerated setting speed and reduced strength, special care is needed when pouring concrete.
Concrete engineering: (1) get in touch with the meteorological department during the rainy season construction and formulate a short-term meteorological forecast.
Treatment measures: (1) regularly inspect the air content of concrete mixture; (2) Increase the amount of air entraining agent.
When the humidity is low or the wind speed is high, the water loss is greater.
In addition, during concrete construction, measures should be taken to improve the construction quality in summer.
3.
(4) Sprinkle water into the aggregate pile to promote evaporative cooling to reduce the temperature of concrete; If it is wetted with cold water (such as groundwater or well water), the cooling effect will be better, especially when the humidity is high.
3.2 the hot climate reduces the air content of concrete, which makes the concrete suffer some adverse effects.
Some superplasticizers can maintain high slump for 2h.
In summer, the temperature is high, the humidity is low, and the drying is fast.
In order to improve the pouring quality of concrete in hot climate, a detailed construction plan is made and implemented.
Even if the increase of water consumption is compensated by increasing the amount of cement, the quality of hardened concrete may still be adversely affected.
In both cases, the water consumption of concrete is increased, resulting in increased shrinkage and reduced strength.
Treatment measures for concrete pouring in summer 3.1 the final strength of concrete poured in hot climate will be reduced, and the influencing factors are: (1) the temperature of concrete is high; (2) The setting and early strength increased rapidly; (3) The water consumption increases under the same slump requirements.
2.
(2) If the concrete mixture needs to be transported for a long distance, retarder can be used to control the setting time, but the correct dosage of retarder should be ensured, which is particularly important for underwater concrete engineering.
