The two most common types of mortar used for bricklaying are cement and lime mortar. They have different properties and strength characteristics, so it is important for contractors to which one to use for a project. LafargeHolcim Tanzania manufactures a few cement products that are suitable for use as mortar in brickwork. These are Tembo cement, TemboFundi and FastPlus.
Here are the things that contractors should know about mortar for bricklaying and brickwork construction:
1. Mortar does not affect the strength of brickwork – Various mortar mixes have different strengths, but they do not affect the overall strength of the brickwork. For example, mortars of mix ratios 1:6 and 1:4 have different strengths, but the brickwork will have the same strength in both cases, regardless. This is because the strength of brickwork depends on the bricks used, not the mortar.
2. An ideal mix ratio is 1:3 – When a mortar is mixed with one part cement (or lime) to three parts sand, it creates a dense mortar with fewer voids. This is an ideal mix ratio for most projects and general applications. A mix ratio richer than 1:3 is not used in bricklaying because of the high shrinkage rate.
3. Lime mortar has a few advantages – Although lime mortar is generally weaker than cement mortar, it does have a few other advantages:
- Lime mortar does not experience as much shrinkage as cement mortar.
- Lime increases the workability and plasticity of the mortar mix.
- Lime has good water retention and the mix does not dry out as quickly.
- Lime can increase the volume of mortar by filling voids.
- Lime makes the mortar more water-resistant and impervious to rain.
4. Lime mortar gains strength slowly – This is the reason why lime has a lower strength than cement. Lime mortar may develop early strength but it does not develop long-term strength as quickly as cement.
5. Cement-lime mortar ratios are important – When mixing cement and lime to form a hybrid mortar, it is important to know that leaner mixes (a ratio between 1:4 and 1:8) tend to be harsh when mixed with coarse sand. In these cases, plasticisers are recommended to help improve the workability of the mortar.
6. Sand affects the strength of mortar – The following factors of sand affect the strength of cement mortar, regardless of the ratio between cement and sand:
- The grading of the sand.
- The fineness or coarseness of the sand.
- The angularity and roundness of the sand particles.
- The fineness or coarseness of sand affects the plasticity of the mortar mix. Plasticity can also be increased by adding more cement to the ratio.
- Fine sand results in a more workable mortar but more cement and water will be needed in the mix. This increases the water-cement ratio which reduces the strength of the mortar.
8. Curing is critical – The curing process is absolutely necessary to achieve the maximum strength of the mortar mix. Curing can take about seven days after bricklaying.
9. Common mistakes in brickwork mortar – The following are common mistakes that are made by contractors when making mortar mixes for bricklaying:
- Not mixing the mortar properly.
- Adding too much water to the mixture.
- Laying a thick bed of mortar between bricks.
- Using dry bricks that suck moisture out of the mortar.
- Uneven joints between corners and bricks.
- Voids in vertical joints between bricks.
- Disturbance of bricks after laying.
10. Addition of pozzolana – Adding pozzolana to the mortar mix increases its strength and makes it more resistant to chemicals and harsh substances.
LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges.
LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.
At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.
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