The water to cement ratio largely determines the strength and durability of theconcrete when it is cured properly. The w/c ratio refers to the ratio of the weights ofwater and cement used in the concrete mix. A w/c ratio of 0.4 means that for every 100 lbs of cement used in the concrete, 40 lbs of water is added.
Different Water-cement ratios are employed for different concrete applications. For high-quality concrete construction, a lower water-cement ratio of 0.4 is employed. For concrete construction like driveways and sidewalks, a w/c ratio ranging from 0.6 to 0.7 is normally used.
The practical range of water-cement ratio ranges from 0.3 to 0.8 that gives stiff and weak concrete respectively. Weak concrete means a fairly wet concrete.
A compressive strength about 5600psi can be obtained from a concrete of water-cement ratio 0.4. This value will go down to 2000psi if a water-cement ratio of 0.8 is used.
