On the use of concrete antifreeze-sodium nitrite

On the use of concrete antifreeze-sodium nitrite

The use of concrete antifreeze is gradually increasing under the decreasing ambient temperature, and the application requirements are gradually increasing. How to protect the newly poured buildings in low temperature environment to maintain the standard performance of the building and avoid the cracks caused by frost damage, we need to use the antifreeze reasonably Sodium nitrite is the most widely used antifreeze. In this article, we will introduce sodium nitrite:

The use amount of sodium nitrite is added according to 2-4% of the cement weight. Before mixing, rinse the mixer with hot water or steam. First add sand, stones and hot water and stir for about 1min, then add cement and antifreeze and stir for 3min. The temperature of the mixing water is determined by ensuring that the concrete entry temperature ≥ 10 ° C. Under the condition of satisfying the normal construction and workability, reduce the water consumption as much as possible; because the free water in the concrete increases, the anti-freezing performance decreases obviously. The concrete mixture mixed with antifreeze has the characteristics of being dry but not hard. Pay attention to control the slump of newly poured concrete not to be too large.

The use of sodium nitrite must strictly control the amount of antifreeze; strictly control the water-cement ratio, the moisture brought by the aggregate and the water in the antifreeze solution should be deducted from the mixing water; before stirring, rinse with hot water or steam Mixer, the mixing time should be 50% longer than normal temperature; the temperature of the concrete mixture with antifreeze should not be lower than 15 ℃ in cold areas; and 10 ℃ in cold areas. The mold entry temperature should not be lower than 10 ℃ in severe cold areas and 5 ℃ in cold areas.

The exposed surface of newly poured concrete should be covered with plastic film and thermal insulation materials in time, and maintained under negative temperature conditions. The concrete shall not be watered. Follow the principle of pouring, vibrating and covering continuously. For the cement, Portland cement or ordinary Portland cement with a strength level above 32.5 is used. Sand and stone should be cleaned and sieved, and must not contain frozen objects such as ice and snow and substances that are easy to freeze and crack.