Detailed technical information or references on cement and concrete can be obtained from the Cement and Concrete Association of Australia library. This library is one of the best sources of information in this specialized area and is also on the web. ... Repair materials.
More water, cement or sand can be added if the mixture is too wet or dry. Below is an example of a sand to cement mix ratio recommendation from a cement manufacturer. Concrete 1 part cement, 2 parts concreting sand and 3 parts 20 millimeter aggregate. Mortar 1 part cement, 4 to 5 parts building sand.