Final answer:
The correct proportion of sand to mortar depends on the construction needs, with 1:3 or 1:4 ratios being common for general construction, while 1:5 and 1:6 are leaner mixes for less strength-dependent applications.
Step-by-step explanation:
When dealing with the proper amounts of sand and mortar for construction, one must understand that the ratio signifies the volume of sand to the volume of cement in the mix. The correct proportion depends on the specific requirements of the construction project. However, a common mix for general construction purposes is a 1:3 or 1:4 sand to cement ratio, meaning one part cement to three or four parts sand by volume, respectively. The 1:5 and 1:6 ratios are leaner mixes that could be used for projects requiring less strength, such as mortar for non-load-bearing walls or for a pointing mortar where a more flexible mortar is required. It is crucial to use the recommended ratio for the specific type of work being done, as the strength and durability of the mortar are greatly affected by the mix.