Cement mortar is one of the most commonly used construction materials in building and infrastructure works. From brick masonry and blockwork to plastering and pointing, it plays a vital role in bonding, finishing, and protecting structural elements. Although it appears simple, a mixture of cement, sand, and water, its performance depends heavily on proper material selection, mix ratios, workmanship, and curing practices.
This technical guide explains what cement mortar is, how it is made, and why its properties matter in real construction conditions. It covers key characteristics, standard mix ratios used for different applications, and the common types of cement mortar adopted in practice. The aim is to provide a clear, field-oriented reference that helps engineers, supervisors, and students apply the right mortar mix for the right job and avoid common site mistakes.
What is Cement Mortar?
Cement mortar is a homogeneous mixture of Portland cement, fine aggregate (sand), and water, proportioned to create a smooth, workable, and consistent material commonly used for masonry, plastering, and bonding applications. The ratio of cement to sand varies depending on the application, from 1:3 to 1:8, but a common ratio is 1:3, which means one part cement to three parts sand. In addition to sand, Pozzolana may also be added to prepare the mortar (Punmia. p214). Water is added to the mixture gradually until it achieves the desired consistency.
Mortar made with cement must be utilised within 30 minutes of adding water or within 1 hour of mixing. Cement-based mortars are typically better for creating high-strength mortars. It is one of the most widely used materials in the construction industry, particularly in masonry work, plastering and pointing works. Sealing the concrete pipe joints and preparing the bed of the manhole or inspection chamber.
Also, read: What is mortar?
Cement Mortar Against Nature of Works
Mortars that are made using Portland cement and blast furnace slag cement are highly effective for constructing walls with bricks, stones, and large blocks. In contrast, mortars made using Puzzolana Portland cement and sulphate-resisting cement are suitable for constructing buildings that are exposed to corrosive and wastewater. Furthermore, it can be utilised for plastering, rendering smooth finishes, and for damp-proof courses.
| Types of Work | Cement | Sand | |
|---|---|---|---|
| Masonry | 1 | 4-5 | |
| Plastering | Internal Plastering | 1 | 4 |
| External Plastering | 1 | 5-6 | |
| Pointing | 1 | 1-3 | |
| Reinforced Brick Work | 1 | 3 | |
| Foundation | 1 | 3-5 | |
From the above table, it is understood that, for brick masonry works or stone masonry works, the cement sand ratio is ideally selected as 1: 4 and 1: 5. There is no harm in applying cement mortar stronger than 1:4 for masonry works but it becomes uneconomical in large scale and it is not advised to apply weaker mortar than 1:5 for the same work.
Also, read: What is Lime Mortar?
Properties of Cement Mortar:
The following are the important properties of cement mortar:
- Adding water to a dry mix of cement and sand initiates the hydration of cement, which binds sand particles and the surrounding surfaces of masonry and concrete.
- Mixes that are richer than 1:3 have a tendency to shrink.
- Mortar that is well-proportioned forms a surface that is impervious.
- Plastered surfaces made using leaner mixes cannot fill the voids in the sand, resulting in a porous surface.
- Table 2 illustrates the strengths achieved with various combinations of cement and sand, demonstrating that the strength of mortar is influenced by the ratio of cement and sand.
| Sl.No | Cement: Sand | Compressive Strength |
|---|---|---|
| 1. | 1:3 | 10N/mm2 |
| 2. | 1:4 | 7.5N/mm2 |
| 3. | 1:5 | 5.0N/mm2 |
| 4. | 1:6 | 3.0N/mm2 |
| 5. | 1:8 | 0.7N/mm2 |
Uses of Cement Mortar:
- It is used to secure and lay different types of masonry elements, such as stones, bricks, and cement blocks.
- It is also utilised in plastering slabs and walls to make them resistant to moisture.
- Additionally, it is used to create a smooth and polished finish on walls and concrete structures (beams, columns, slabs, etc).
- CM can be used for preparing beds for laying tiles.
- Another application of mortar is to fill gaps and crevices between masonry units.
- It is also used in the production of building blocks and as a filler material in ferrocement works.
- Moreover, it can be utilised to fill in joints and cracks in walls as well as in stone masonry.
- Portland cement mortar may also be used to fill the gap between the eave tiles and the underlying part of the roof.
Also, read: Types of Plaster Finishes
FAQs:
Q. What is cement mortar?
Answer: A homogeneous mix of cement, fine aggregate, and water is known as cement mortar.
Q: What is the thickness of cement mortar for masonry works?
Answer: For the masonry works, the thickness of the cement mortar is recommended between 10 to 15 mm thick.
Q. What are the different types of cement mortar?
Answer: The most common types of cement mortar include cement-lime mortar (Gauged mortar), cement-sand mortar (cement mortar), and cement-lime-sand mortar. The type used depends on the specific application and the desired properties. However, cement-sand mortar is the most common type of mortar.
Q. What is the function of cement mortar?
Answer: The main function of CM is to bind together masonry units such as bricks, stones, or blocks. It is also used to create a smooth and polished finish on walls and concrete structures, fill gaps and crevices between masonry units, and as a filler material in Ferro cement works.
References:
- Bureau of Indian Standards. (1981). Code for Practice for Preparation and Use of Masonry Mortars (1st rev.) (IS 2250).
- Punmia. B.C (2006). A Textbook of Building Construction. Laxmi Publications (P) Ltd.
- Bhavikatti, S. S. (2010). Basic civil engineering. IK International Publishing House Pvt. Ltd.
- Mehta, M., Scarborough, W., & Armpriest, D. (2017). Building constructions: Principles, materials, and systems. Pearson Education, Inc.
- Cement mortar. (n.d.). Designing Buildings. https://www.designingbuildings.co.uk/wiki/Cement_mortar
- Sulphate Resistant Cement – Composition, properties, uses and advantages. (2018, August 25). theconstructor.org. https://theconstructor.org/concrete/sulphate-resistant-cement/23428/
