Quick-hardening Portland cement (BTC), which meets the requirements of VTU No. 29-55 MPSM of the USSR, provides an intensive increase in concrete strength in the first hardening period.
The strength of such a cement during compression (with standard testing and normal hardening) should be not lower than 200 kg/cm after 1 day and 300 kg/cm after 3 days, and with the optimal string mode-300 kg/cm? After 1 day. For fast hardening of this cement, a positive temperature is required at least 20 °.
Another way to accelerate concrete hardening is an additional additive of gypsum to the cement, which, due to the reaction of three -kebacial aluminum with gypsum, usually leads to acceleration of hardening and increasing the strength of concrete. An additional additive of gypsum to highly aluminum cements increases concrete strength by 2-3 times at one-day age. The disadvantage of this method is the need to introduce additives at the place of production of gypsum and carefully mix it dry with cement or grind it together.
Parquet cycles has its own characteristics. This process requires certain skills, so it is worth inviting experienced craftsmen to work. Then the result will be first -class.
Gypsum additive can be combined with the addition of calcium chloride. With a 4 percent additive of gypsum and 2% calcium chloride from the weight of the cement, a rapidly hardening concrete was obtained with daily strength, which is 65% of the design brand.
One of the means of acceleration of concrete hardening is the domain of ordinary cement, causing its activation. Domole is produced in vibromelnits. Wet domolo with gravel or crushed stone of solid breeds can also be used directly in the concrete mixer, from which the blades are removed. After a wet house of ordinary Portland cement of the brand “400” with its consumption of 300 kg/m3 and iv = 0.50 pererching for 5 hours. gave 80 percent strength of concrete from the project brand.
