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A collapse slump is an indication that the mix is too wet. Only a true slump is of any use in the test. A collapse slump will generally mean that the mix is too wet or that it is a high workability mix, for which the slump test is not appropriate.Drying shrinkage is defined as the contracting of a hardened concrete mixture due to the loss of capillary water. This shrinkage causes an increase in tensile stress, which may lead to cracking, internal warping, and external deflection, before the concrete is subjected to any kind of loading.Another “old rule of thumb” for mixing concrete is 1 cement : 2 sand : 3 gravel by volume. Mix the dry ingredients and slowly add water until the concrete is workable. This mixture may need to be modified depending on the aggregate used to provide a concrete of the right workability.Curing is the maintaining of an adequate moisture content and temperature in concrete at early ages so that it can develop properties the mixture was designed to achieve. Curing begins immediately after placement and finishing so that the concrete may develop the desired strength and du- rability.So if one cubic yard of the mix has 235 pounds of water and 470 pounds of cement- the mix is a .50 water to cement ratio. If the mix lists the water in gallons, multiply the gallons by 8.33 to find how many pounds there are in the mix. Learn how to properly cure a concrete slab.The fineness of cement is measured by sieving it on standard sieves. The proportion of cement of which the grain sizes are larger than the specified mesh size is thus determined.Portland cement comes in a variety of different types.Type II is a moderate sulfate resistant cement, important when concrete is cast against soil that has moderate sulfate levels. Type III is a high early strength cement. It is ground finer and reacts faster than Type I, so the early strength gains are greater.