The table below can be used to estimate how much cement , sand and hollow blocks will be needed to build a wall of a given area in square meters. Each square meter requires about 12.5 hollow blocks. Class B is a mixture of sand and cement (mortar) with a 1 is to 3 ratio of cement and sand. Class C has a ratio of 1 part cement per 4 parts sand. This mortar is used as filling for the hollow blocks.
Concrete is a mixtureof sand gravel cement and water. Concrete used for beams (biga), columns (poste) and slabs have a 1 : 2 : 4 proportion. Thats one part cement, two parts sand and four parts gravel. A bag of cement is about one cubic foot. Add two cubic feet of sand and four cubic feet of gravel to make to make seven cubic feet of concrete. Concrete used for mortar (filling for concrete hollow blocks) will vary from 1 : 2 (class A) to 1 : 4 (class C) cement and sand ratio.