The water cement ratio first of all determines concrete durability. To find out how many it is necessary for liquid in any given solution, it is necessary to pay attention to quality of cement, filler type, its purity and humidity.
The water cement ratio is exact proportion of water and cement as a part of concrete. It defines what will be its fortress, therefore, and quality.
Influence of water on characteristics of concrete
If in cement and sand solution there is excess amount of liquid, it will lead to formation of time in structure of monolith and as a result, to decrease in its durability. Liquid solution is quickly distributed in form (timbering) and soon begins to filter through the slightest slots. Following, water carries away with itself cement as this binding is the easiest solution component on weight. Such concrete long grabs for the reason that the liquid evaporation period very considerable. In most cases it leads to cracking of construction stone.
For rigid M75 concrete optimum water cement ratio – 0.6. Therefore, preparation of 1 m3 of this solution will require 150 l of water. But that calculation was absolutely exact, it is necessary to understand function of liquid in solution. At water their two: takes part in the chemical processes happening during cement hardening and provides mixes relative plasticity (fluidity). This property very important as provides lack of air bubbles in structure of concrete. Therefore for rigid structures the consolidation (tamping) of cement and sand solution is so necessary regardless of which the type of filler is used. This work is performed manually or by means of special vibration purpose tool (vibrating plates).
How to learn exact water cement ratio?
The water cement ratio is determined most often by special tables. But experienced builders can do it on condition of solution in the concrete mixer. If water in mixing ratio is not enough (no more than 30% of total amount of cement), then receive rigid concrete. If there is a lot of – that fluid. The large role in definition of water cement ratio is played by humidity and purity of filler. For example, if sand of clay, natural with impurity, proportion cement-water it is necessary to adjust. It is important to pay attention and to quality of cement. It is necessary to understand that for month of storage it loses not less than 10% of the properties of binding substance. In three months of loss will increase up to 20%, in half a year – up to 30%. All this will affect the required amount of water for receiving concrete of due durability. As coarse aggregate it is not recommended to use calcareous crushed stone as this stone has rather high hygroscopicity that does not allow with accuracy requirement to define the required water cement ratio for concrete of certain brand.