Mortar is a fundamental building material that has been used for centuries in construction. It serves as a bonding agent between bricks, stones, or other masonry units, providing strength, stability, and durability to the structure.

Composition of Mortar:

Mortar is typically composed of a mixture of cementitious materials, aggregates, and water. The primary cementitious material used in mortar is usually Portland cement, which is a fine powder made from limestone, clay, and other minerals. Aggregates, such as sand, are added to provide bulk and improve workability. Water is incorporated to activate the cement, causing it to harden and bind the mortar ingredients together.

Types of Mortar:

Cement Mortar:

Cement mortar is the most common type of mortar, consisting of Portland cement, sand, and water. It is widely used for general masonry applications, including brickwork, blockwork, and plastering. Cement mortar provides excellent compressive strength and durability.

Lime Mortar:

Lime mortar is a traditional mortar that predates cement mortar. It is made by combining lime, sand, and water. Lime mortar is known for its high elasticity and breathability, allowing it to accommodate slight movements in the masonry without cracking. It is commonly used in historic restoration projects and for buildings with soft or brittle masonry materials.

Gypsum Mortar:

Gypsum mortar is composed of gypsum plaster, sand, and water. It is primarily used for interior plastering and decorative purposes. Gypsum mortar sets rapidly and provides a smooth, white finish. However, it is not suitable for damp or exterior environments as it is not as durable as cement or lime mortar.

Masonry Cement Mortar:

Masonry cement mortar is a pre-blended mortar that combines Portland cement, hydrated lime, and sand. It offers the convenience of a ready-to-use mortar mix and is commonly used for non-load-bearing masonry applications, such as stonework veneers and bricklaying.

Polymer-Modified Mortar:

Polymer-modified mortar is a contemporary mortar that incorporates polymers, such as latex or acrylic, into the mix. The addition of polymers enhances the mortar's flexibility, bond strength, and resistance to cracking. It is often used in areas prone to high vibration or where increased adhesion is required, such as tile installations and repair work.

Applications of Mortar:

Mortar finds extensive application in the construction industry, including:

Brickwork and Blockwork:

Mortar is used to bond bricks or blocks together in walls, arches, and other structural elements. It provides strength, stability, and weather resistance to the masonry.

Plastering and Rendering:

Mortar serves as a base for plastering and rendering, providing a smooth and durable surface for interior and exterior finishes.

Masonry Repairs:

Mortar is used for repairing damaged or deteriorated masonry, filling cracks, and restoring the structural integrity of buildings.

Tile Setting:

In tile installations, mortar acts as an adhesive to bond tiles to the substrate. It provides support, ensures even spacing, and accommodates minor adjustments.

How Strong Is Mortar?

The strength of mortar can vary depending on several factors, including the type of mortar, the proportions of its ingredients, curing conditions, and the specific application. Mortar strength is typically measured in terms of compressive strength, which refers to its ability to withstand compression or downward force.
The strength of mortar is influenced by the following factors:

Type of Mortar: Different types of mortar have varying strength characteristics. Cement mortar, which is the most common type, generally provides high compressive strength. Lime mortar, on the other hand, may have lower compressive strength but offers greater flexibility and breathability.
Proportions of Ingredients: The proportions of cementitious materials (such as Portland cement or lime) to aggregates (typically sand) can impact the strength of the mortar. The correct balance is crucial to achieving optimal strength. Too little cementitious material may result in weak mortar, while an excessive amount can lead to shrinkage and cracking.
Curing Conditions: The curing process significantly influences the strength development of mortar. Proper curing involves maintaining adequate moisture levels and controlling temperature conditions during the initial setting and hardening stages. Adequate curing allows the mortar to gain strength gradually over time.
Water Content: The amount of water used in the mortar mix affects its strength. The water-to-cement ratio should be carefully controlled to ensure proper hydration of the cementitious materials. Excess water can weaken the mortar, while insufficient water can lead to incomplete hydration and reduced strength.

Generally, cement mortar can achieve compressive strengths ranging from around 7 MPa (1,015 psi) to over 30 MPa (4,350 psi), depending on the specific mixture proportions and curing conditions. Lime mortar typically has lower compressive strength, typically ranging from 0.7 MPa (100 psi) to 7 MPa (1,015 psi).

Items