Proper use of additives to concrete

Proper use of additives to the concrete - another condition for the proper preparation of concrete. For example, calcium chloride, known as hardening accelerator and antifreeze additive, resulting in accelerated electrochemical corrosion of the reinforcement, so that the concrete must be added inhibitors - substances that prevent corrosion. Additives in large amounts cause harm non-reinforced concrete, reinforce the phenomenon of surface filtration, an indicator which can often be a blemish. Mixing concrete - the next stage of preparation of concrete, and here too it is very important to eliminate significant errors possible during this process. Mixing must be thorough in all phases, especially without adding water, otherwise the process of cement (hydration) is incomplete, there will be shortage of concrete strength. The first wet mixing (and subsequent), produce, irrigating solution from a watering can instead of a bucket, as the flood waters wash away the cement. Initially, pour one-third of water needed for the second time - the remaining water, mixing is carried out on a flat, clean, damp ground. In the manufacture of concrete mix two men with shovels throwing gravel in the direction of stirring, the third crushes rake formed a cone, the fourth adds water. In the individual building is often used a small mixer gravity. The optimum time of mixing in such mixers - a few minutes. Short or long mixing time leads to the fact that the concrete mixture is obtained by heterogeneous, with all ensuing consequences. One of the mistakes of preparation of concrete in the cold season: the mixing of warm water with cement and then adding gravel. Download components in the mixture should be as follows: water, heated to a temperature of 60-70 ° C, to be confused with unfrozen gravel, then begin to adulterate cement. If you mix the first warm water with cement, it begins to quickly grasp, the mixture turns patchy, and as a result of the strength of concrete is reduced. Very important and proper transportation of concrete. When carried in wheelbarrows should be no shaking, leading to a separation of the concrete and the use of conveyor concrete mix must be submitted in slaboplastichnom condition, thick, and the height of the relief does not exceed 1.5 m. When purchasing concrete and Concrete truck delivering it to such concrete can not be added water, which is often quite wrong to developers. Indeed, the plastic concrete is easier to lay the formwork, but the addition of water already on site dramatically reduces the strength of concrete.