Cement is the glue that binds materials together. It constitutes building material mixes:
Chemical and mineral additives and admixtures may be added to improve concrete or mortar performance.
Each concrete design mix requires a different amount of water, depending on the expected concrete performance. However, as a rule of thumb, the lower the amount of water used, the better the concrete's strength development is. Therefore, a water to cement ratio of 0.4 is the most desirable. This translates to 20 liters of water per 50kg bag of cement. It is ideal to use 12 liters of water in the initial mix, and adjust accordingly until the desired slump or flow is attained; however, the maximum amount should not be more than 20 liters of water per bag of cement.
Usual reinforced concrete structures (residential, pavements and roads) have a standard 1:2:3 mix; this means 1 bag of cement, 2 cubic feet of sand and 3 cubic feet of coarse aggregates.
For mortar, a standard mix of 1 bag of cement to 4 cubic feet of sand is suitable.
Masonry cement is supposed to be used only for masonry works -- block-laying, plastering and sometimes for toppings. The focus of masonry cement is not on strength but more on workability and board life; since all concrete structures require minimum compressive strengths, masonry cement will not be able to achieve these strengths.
In ideal situations a bag of cement can be stored for three months; after this, it is required that the cement must be retested to be recertified that it still complies with the minimum and maximum requirements of the standards. However, if you notice hardening in the cement, please call your supplier so the proper personnel from Lafarge can examine and assess your cement's condition.
