Photo: Arvo Tarmula Hot degrees require good planning and quick action in concrete works. Lauri Labe, quality manager of concrete master, explains what kind of weather factors you need to keep an eye on and shares advice.
According to a concrete expert, the main factors are temperature, humidity and wind. “In general, it is recommended to carry out concreting works when the air temperature is between 10-20 degrees. You should be especially careful in hot weather, as high temperatures accelerate the drying of concrete, which can cause cracks and weaken the strength,” Labe explains.
According to him, the optimum air humidity for concreting is usually between 40-70%. “Too high humidity can slow down the setting of concrete, while too low humidity can accelerate moisture loss from concrete, which can affect strength and cause cracks,” explains Labe, adding that strong wind can also accelerate the drying of the concrete surface and increase moisture loss.
“If the air temperature exceeds 25 degrees, concrete works should be postponed if possible or done early in the morning or late in the evening when it is cooler,” advises the concrete master.
With high temperatures, good planning is even more important
“Local weather conditions and temperatures should be taken into account and the work schedule planned accordingly. In addition, you should be prepared for more frequent failures, for example, you could have a backup vibrator on the site,” advises Labe and emphasizes that the team’s ability to act actively also decreases in hot weather.
According to the expert, in addition to planning the work, it is also important to choose a suitable concrete mix, which is designed for concreting in hot summer weather. “Such mixes contain special additives that improve the workability of the concrete and extend the workability time,” explains Labe and emphasizes that under no circumstances should water be added to the concrete mix on site, because in this case the manufacturer cannot guarantee the required properties of the ordered concrete mix and hardened concrete.
You must not lose vigilance with follow-up care either
According to a concrete expert, when concreting in hot weather, it’s important to keep the concrete surface moist by using wetting, concrete coating or aftercare chemicals. “The surface of the concrete should be moistened regularly, especially during the first few days after pouring. A sprinkler system, for example, is very suitable for this. If the irrigation is not sufficient or is not possible, the surface of the concrete could be covered to preserve moisture,” says Labe and recommends using a transparent construction film for covering, because it is also possible to visually monitor whether the structure is sufficiently moist under the film.
“If coating and wetting is not possible, there is also a special chemistry that forms a thin protective layer on the surface of the concrete, which prevents moisture from evaporating too quickly. For structures that require subsequent treatment, such as machine sanding or other surface treatment, it is also wise to use an intermediate treatment agent that is sprayed onto the concrete surface immediately after installation and protects the concrete until it has set sufficiently to carry out the next stage of finishing work. At the end of the work, the final aftercare material must be installed,” explains Labe. The expert emphasizes that the temperature of the concrete should be monitored regularly, for example with the help of temperature sensors or loggers that allow measuring the temperature inside and on the surface of the concrete. “If the temperature rises too high or the differential between the concrete and its surface is too large, different stresses and structural damage can occur in the concrete, which can cause cracking, peeling and a decrease in strength,” Labe explains the need for monitoring.
In order to ensure the quality and durability of the concrete, it is important to follow the concrete manufacturer’s instructions when performing concreting work and, if necessary, an expert should be consulted.
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