Mortar is the pasting that holds bricks, stones, blocks, etc. in construction together. It is put in the gaps between each brick, holding multiple blocks in place. Mortar is the product of sand and cement, and is applied in thin layers between bricks. It is very sticky, but does not exactly classify as glue, as it is not an adhesive.
There are 4 types of mortar mixes available in the market, which are N, O, S, M. Most masonry experts recommend the use of type N for normal household repairs and small construction work, as it is a general purpose mix. Given here are the key ingredients used in making this mix, followed by its accurate ratio.
For different mix types and needs, the ingredients have to be used in varying proportions. It is important to note, that most ingredients are sold by weight, whereas mortar mix recipes will mention them in volume. Therefore, you may have to do some calculations, so that you have the right proportions and you do not run short of any ingredient.
Cement bags are available in various sizes, and as they have a tendency to go bad after a period of time, too many bags should not be stocked. Depending on your needs, choose the type of cement accordingly. The quick drying variety is used in most construction activities.
To ensure that the cement does not dry out quickly or shrink, lime is added. This ingredient reduces the quantity of water that is soaked by the bricks. There are three main types of lime available. The hydraulic type sets when it is combined with water; non-hydraulic hardens by drying out; while the semi-hydraulic dries out like the non-hydraulic variety.
If you are using hydraulic lime, then it should be used straight out of the bag, as it is processed before it is packed. On the other hand, if the other two types are used, they should be soaked in water overnight, before use. Excess water will accumulate on top, which can be drained. Then mix this soaked lime in sand, before adding cement to it.
The variety of sand used for bricklaying mortar, building foundations, paving slabs, wall rendering, etc. is the soft type, which is called builder's sand. It is a smooth kind of sand and has cohesive properties. The other type used is sharp sand. It has a gritty feel to it and is used in concrete, and can also be used for rendering walls and floors.
Aggregate is also known as ballast. It is made up of gravel and sand. The gravel used is of a minimum of 28 mm and maximum 50 mm in diameter. Ballast is also graded, depending on the size of the stones.
The Ratio for ...
The type of mortar you use, and its purpose, usually dictates the proportion of the ingredients to be mixed.
- Pointing and General Purposes - 1 part cement : 1 part lime : 5 parts builder's sand
- Stone - 1 part cement : 4 parts sharp sand
- Garden Walls - 1 part cement : 5 parts aggregate
When you use mortar for pointing or general purposes, then ensure that you use only the required amount of water. This is so that the mix sticks to the trowel and does not become thin.
On the other hand, the mix for stones should be stiffer as compared to that for general purposes. For garden walls should be of consistency which pours easily. Make sure to cover your hands and eyes well when you are working on any construction related task.