Understanding Mortar: Types, Properties, and Uses in Masonry

Mortar is a necessary  building material that helps stick bricks, stones, or concrete blocks together to form sturdy structures. There are different types of mortar, such as those made with cement, lime, or epoxy, each designed for specific uses. Some mortars are strong, some are easy to apply, and others set quickly. Understanding these properties is important to make sure you choose the right mortar for your building project, making sure the structure will be durable and perform well.

Mortar for Masonry: Types, Properties, Uses & Precautions

"One tonne of ready mixed lime: sand, when gauged with the specified quantity of cement on-site, will generally be sufficient to lay approximately 1000 bricks", according to the Brick Development Association in the UK. These numbers show the importance of a fundamental understanding of mortar before mixing!

From traditional construction to modern innovations, mortar for masonry is pivotal in achieving structural integrity. However, proper precautions, like maintaining correct water ratios and protecting against harsh weather, are vital to prevent cracking and deterioration, ensuring masonry projects stand the test of time.

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What is Mortar?

Mortar in masonry serves as a crucial bonding agent during construction. It is usually created by combining a cementing or binding material, like lime or cement, with a fine aggregate and water. The main purpose of mortar is to firmly bind various building blocks, such as bricks and stones, creating a strong and stable structure. Moreover, mortar's versatility allows it to be used creatively, forming decorative patterns within brick or stone masonry, adding strength and aesthetic appeal to the finished construction.

What are the Different Types of Mortar Used in Masonry?

Each mortar type presents distinct properties and advantages, catering to specific construction needs and ensuring the longevity of masonry structures. Depending upon the materials used for mortar mixture preparation, the mortar could be classified into various types: 

Cement Mortar

Cement mortar, composed of cement as the binding material and sand as the fine aggregate, finds a wide range of uses in construction. It is a fundamental bonding agent for various building blocks, like bricks and stones, ensuring structural integrity and stability. Cement mortar is commonly used for masonry, plastering walls, and laying floors, providing a strong and durable bond between surfaces. Its versatility allows it to adapt to different construction needs, making it a reliable choice for traditional and modern building projects.

Lime Mortar

Lime mortar incorporates lime as the binding material (fat lime or hydraulic lime) and sand as the fine aggregate, which serves distinct purposes in construction. Due to its compatibility with historical restoration projects, lime mortar is commonly used for preserving heritage structures like Independence Hall. Its breathable properties make it ideal for older masonry, allowing moisture to escape and preventing damage from trapped water. Additionally, lime mortar's flexibility and self-healing abilities contribute to its durability over time. It remains a preferred choice for restoring historic buildings and ensuring their continued preservation for future generations.

Surkhi Mortar

Surkhi is a powdered form of over-burnt broken brick or clay balls. In specific construction scenarios, a mason would opt for surkhi mortar, consisting of lime as the binding material and surkhi as the fine aggregate. Surki mortar proves economical and is commonly used in less critical areas of masonry work where high strength is not a primary requirement. Its cost-effectiveness makes it a practical choice for non-load-bearing walls, plastering, or as a base coat before applying a final finish. With lime's inherent qualities and surkhi's availability, this type of mortar offers an efficient and budget-friendly solution for certain construction projects.

Gauged Mortar

The gauging process for gauged mortar involves combining two binding materials, cement, and lime, with sand as the fine aggregate. The purpose is to create a mortar that harnesses the best properties of both materials. Typically, the proportion of cement or lime to sand is carefully measured to achieve the desired balance of strength, workability, and durability. The gauging process ensures that the resulting mortar possesses enhanced properties compared to traditional lime mortar, offering higher strength while still being more economical than pure cement mortar. It is useful for various masonry projects, like building walls, foundations, columns, and floors, as well as for plastering and repairs. 

Mud Mortar

Mud mortar mixes mud as the binding material and sawdust, rice husk, or cow dung as the fine aggregate. It becomes a valuable option where lime or cement might not be readily available or affordable. Mud mortar's eco-friendly nature makes it sustainable and suitable for certain traditional or rural building practices. Additionally, it exhibits decent thermal insulation properties, making it beneficial for regions with extreme climates. Although it may not possess the same strength as cement-based mortars, mud mortar's accessibility, affordability, and environmentally-friendly characteristics make it a viable choice in appropriate building scenarios.

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What are the Properties of Good Mortar

Good mortar provides structural integrity, ensuring the stability and durability of the construction. The following is a list of key ideas to look for when observing high-quality mortar:

• It should possess strong adhesion, effectively binding building units like bricks and stones
• Water resistance is important, allowing the mortar to resist water penetration
• Low deformability is preferred to maintain the structure's integrity
• Ideally, mortar should be cost-effective
• It needs to be easily workable according to site conditions
• Good mortar should have high mobility for thin and even application
• High durability ensures the longevity of the structure
• Quick-setting mortar can improve the speed of construction
• It should not develop cracks, ensuring longevity without losing appearance

What is Mortar Mix Used for?

Mortar mix is an indispensable material in civil engineering, acting as a vital bonding agent between various building materials. Comprising water, fine aggregates like sand or surkhi, and binding materials such as cement or lime, mortar finds diverse applications in construction:

• Binds bricks or stones in masonry
• Provides a soft, even bed between masonry layers for equal pressure distribution
• Fills spaces between bricks or stones, making walls tight
• Serves as a matrix in concrete
• Used in plastering works to conceal joints and enhance appearance
• Utilized for molding and ornamental purposes

What Precautions are Required while Using Mortar Mix?

To ensure optimal use of mortar mix, consider the following precautions:

• Mix mortar in small quantities before setting; avoid using set mortar

• Time limits for usage post-grinding vary by ingredients:

Hydraulic lime (Class A lime) - use within 4 hours

Surkhi - use within 24 hours

Cement mortar - use within 90 minutes of adding water

• Bricks or stones should be thoroughly soaked in water for at least 12 hours before use to prevent moisture absorption from the mortar
• Excess water in mortar should be avoided and as stiff as possible without causing inconvenience
• Fresh water, free from oils, dust, and alkalies, should be used in the mortar mix.
• Avoid the use of seawater in the mortar mixture
• Joints should be well-filled with mortar
• After casting, keep mortar works wet for 1-2 weeks to prevent rapid drying, especially in hot weather
• Avoid working in frosty weather as it affects the setting of cement

Considering the various requirements recommended, we advise that you seek professional guidance from masonry contractors with sufficient experience. Contact APS Masonry today!

What is the function of sand in mortar?

Sand is a commonly used ingredient of mortar. The quality of sand is important to produce good mortar. Important notions to consider: 

• Sand in mortar mainly acts as an inert material, increasing the volume for economic benefits.
• Correct proportions of sand can make mortar affordable without compromising its strength.
• It subdivides the paste of cementing materials into a thin film, a basic principle in using cementing materials.
• The thin film provides surface area for adhesion and spreading. - Sand can prevent shrinkage and cracking of mortar during setting.
• Well-graded sand enhances the density of the mortar.
• In lime mortars, sand allows Carbon-Dioxide from the atmosphere to penetrate, improving setting capability.
• There may be a chemical reaction between sand silica and the cementing materials' constituents, contributing to a hardened mass.

What is the difference between mortar and concrete?

When it comes to concrete vs mortar, the main differences between them lie in their strength and primary functions. Mortar is less robust than concrete and is typically not used as the primary building material. Instead, it is the glue that binds bricks, concrete blocks, stones, and masonry elements together. Concrete, on the other hand, is a much stronger material and is commonly employed as the main structural component in construction projects, providing the framework and load-bearing capacity for buildings and infrastructure.

How do I choose the right masonry mortar type for my project?

When choosing the right masonry mortar type for your project, several factors should be considered. Firstly, assess the project's structural requirements and load-bearing capacity to ensure the mason's expertise aligns with the specific needs. Secondly, evaluate the environmental conditions and exposure to elements, as this can influence the choice of materials and construction techniques. Lastly, select a mason who understands the importance of using the appropriate mortar type, considering factors like compatibility with the masonry units and the desired aesthetics to achieve a successful and durable outcome.

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