Mortar and Grout: Comprehensive Guide to Composition, Types, and Differences

What is Mortar?

The term mortar is used to indicate that a paste prepared by adding the required quantity of water into a mixture of binding material (cement or lime) and fine aggregate (sand). The above two elements of mortar, namely, the binding material and fine aggregate, are sometimes referred into as the matrix and adulterant, respectively.

The matrix binds this particle of the adulterant. The durability, quality, and strength of mortar will mainly depend on the quantity and quality of the matrix. The combined effect of the two components of mortar is that the mass can binds the bricks or stones firmly.

Classification/ Type of Mortar

The classification of mortars may be done in many ways, i.e., based on the binding agent, possessions of binding agent and aggregate, etc.

In general, Mortar are classified as follows:

1. Cement Mortar
2. Lime Mortar 
3. Lime-Cement Mortar
4. Special Mortar

Cement Mortar

Cement mortar consists of cement as binding material, sand into different proportions, and water. It’s the strongest type of mortar and is therefore preferred to be used in the construction of structures subjected to heavy loading.

Lime Mortar 

Lime mortar can be lime and sand mortar, lime, and surkhi mortar, sand, lime, and surkhi mortar or lime and cinder mortar (also known as black mortar). Lime used for mortar can be fat lime (quick or hydrated lime) or hydraulic lime. Fat lime has a high calcium oxide content.

It’s hardening solely depends on the loss of water and absorption of carbon dioxide from this atmosphere and possible recrystallization in due course. Hydrated lime is a dry powder obtained by treating quick lime with water enough to satisfy its chemical affinity for water under the conditions of its hydration.

Hydraulic lime contains small quantities of alumina and silica and/or iron oxide, which can be in chemical combination with a few of calcium oxide contents, giving a putty or mortar that has the property of setting and hardening underwater. Slaked fat lime is used to prepare mortar for plastering, whereas hydraulic lime is used in preparing mortar for masonry construction.

Lime-Cement Mortar

It’s also called composite mortar or gauged mortar. When lime mortar made from fat lime is desired to be improved with regard to its hydraulic properties, initial setting time and strength, cement is added into it. Cement should be added only to that much quantity of lime mortar, which can be used within an hour after the addition of cement.

Special Mortar

Following are the few special Kinds of mortars based on the binding material or certain specific characteristics:

1. Mud mortar,
2. Cement-clay mortar,
3. Light and heavy mortars,
4. Decorative mortars,
5. Air-entrained (plasticized) mortar,

Test for Mortars

To test the quality of mortars, these can be subjected to several tests:

1. Crushing Strength 
2. Adhesiveness
3. Cohesiveness or Tensile Strength 
4. Test for Setting 

What is Grout?

Grout is used to filling pints between tiles and is selected with a compatible mortar. Grout is either a portland cement-based mixture or a mixture of other compounds to enhance its performance or ease its installation. The type and size of tile, service level, climatic conditions, tile spacing, and individual manufacturer’s recommendations are factors that should be considered when selecting grout.

Portland cement-based grout is a mixture of portland cement and sand (for floors) or lime (for walls) and is used for thickset installations. Portland cement-based grouts include commercial portland cement grout, sand portland cement grout, dry set grout, and latex portland cement grout.

Grouts based on mixtures of other compounds include solid epoxy, furan, silicone, and mastic grouts. Mastic grout eliminates the need for mixing on-site.

1. Epoxy grout is a two- or three-part mixture (epoxy resin hardener with silica sand filler) that is highly resistant to chemicals and has great bond strength. This grout and furan grout are made for different chemical and solvent resistance
2. Furan resin grout is a two-part furan mixture (similar to loran mortar) that resists high temperatures and solvents
3. Silicone rubber grout is an elastomeric mixture of silicone rubber. It has high bond strength, is resistant to water and staining, and remains flexible under freezing conditions.

Silicon, urethane, and modified polyvinyl chloride are used in pre-grouted ceramic tile sheets. Silicone grout should not be used on kitchen countertops or other food preparation surfaces unless it meets the requirements of FDA Regulation No. 21, CFE 177.2600. Joint widths are only guidelines.

Individual grout manufacturer’s products may vary. Consult the manufacturer’s instructions. Joint width is only guidelines. Individual grout manufacturer’s products may vary. Consult the manufacturer’s instructions. Some types of glazed ceramic tiles, polished marble, marble agglomerates, and granite can be permanently scratched or dam-aged when grouted with sanded grout formulas.

Do not use sanded grout or add sand to grout when grouting polished marble, marbled agglomerates, and ceramic wall tiles with soft glazes. Check the tile or marble manufacturer’s literature and test grout on a separate sample area prior to grouting.

Some types of ceramic tiles and dimension stones may be permanently stained when grouted with pigmented grout of a contrasting color. White grout is best suited for grouting white or light-colored marble or granite. Colored cementitious grouts may darken when wet.

Type of Grout

To test the quality of mortars, these can be subjected to several tests:

1. Dry-Set Grout
2. Latex Grout
3. Silicone Rubber Grout
4. Epoxy Grout
5. Furan Resin Grout

Dry-Set Grout

Dry-Set Grout is a prepared mixture of portland cement and sand, with additives to improve water retentivity. Dry-set grout has the same properties as dry-set mortar and is suitable for grouting walls subject to ordinary use. It eliminates soaking of tile, although dampening sometimes is desirable under very dry conditions.

Latex Grout

Latex grout is a mixture of one of the three preceding products, consisting mainly of portland cement with a latex additive to increase stain resistance and resilience of the joints. Latex grout is suitable for installations subject to ordinary use.

It is less rigid and less water-permeable than sand-portland cement grout, allowing for more movement and greater exposure to moisture. This grout, therefore, is particularly suitable for tub and shower areas.

Silicone Rubber Grout

Silicone rubber grout is an engineered elastomeric grout system for interior use employing a single-component nonslumping silicone rubber, which, upon curing, is resistant to staining, moisture, mildew, cracking, crazing, and shrinking. It adheres tenaciously to ceramic tile, cures rapidly, and withstands exposure to moisture as well as subfreezing temperatures and hot, humid conditions.

Epoxy Grout

1. Epoxy grout is a two-part system consisting of an epoxy resin and a hardener.
2. It is made in several formulations, each intended for a specific ceramic tile.
3. It is highly stain-resistant and impervious and is used with epoxy mortar or epoxy adhesive.
4. Its use requires special skills and is usually expensive.
5. Epoxy grout is formulated without coarse fillers that might scratch glazed wall tile or mosaic tile.
6. It may be used on floors, walls, and counters subject to food staining.
7. It is also formulated with a coarse silica filler for use with quarry tile and pavers.
8. It is formulated for industrial and commercial installations where chemical resistance is of paramount importance.
9. It has excellent bonding characteristics.

Furan Resin Grout

1. Furan resin grout is a two-part grout consisting of furan resin and a hardener.
2. It is intended for use with quarry tile and quarry tile and pavers, mainly in industrial areas requiring a maximum of chemical resistance.
3. It is generally used in conjunction with furan mortar.

Difference Between Mortar and Grout ( Mortar Vs Grout )

FAQs about Mortar and Grout

What is the main difference between mortar and grout?

Mortar is a paste used primarily as a binding agent in masonry to hold bricks or stones together. It has a lower viscosity and is used in joints and plastering. Grout, on the other hand, is used as a filler material to fill gaps between tiles or in cracks, and has a higher viscosity.

What are the common types of mortar?

The common types of mortar include Cement Mortar, Lime Mortar, Lime-Cement Mortar, and Special Mortars (such as Mud Mortar and Cement-Clay Mortar).

What types of grout are available?

Grout types include Dry-Set Grout, Latex Grout, Silicone Rubber Grout, Epoxy Grout, and Furan Resin Grout.

How do you choose between different types of mortar and grout?

The choice depends on the application and requirements: Cement Mortar is used for heavy-loading structures, Lime Mortar is used for masonry with hydraulic properties, and grouts like Epoxy and Silicone Rubber are selected based on chemical resistance and flexibility needs.

How is mortar tested for quality?

Mortar quality is tested through several methods including crushing strength, adhesiveness, cohesiveness (tensile strength), and setting tests.

What factors should be considered when selecting grout?

Factors include the type and size of tile, service level, climatic conditions, tile spacing, and the manufacturer’s recommendations.

Can grout be used in outdoor applications?

Yes, but you should select grout types that are suitable for outdoor conditions, such as Epoxy Grout or Furan Resin Grout, which offer better resistance to weather and environmental conditions.

How should mortar and grout be applied for best results?

Mortar should be applied evenly between bricks or stones, and cured properly. Grout should be filled into joints and then cleaned off the tile surface before it sets to ensure a smooth finish.

What precautions should be taken when using grout on polished surfaces?

Avoid using sanded grout on polished marble or ceramic tiles with soft glazes, as it may cause scratching or damage. Always test grout on a separate sample area first.

How do curing requirements differ between mortar and grout?

Mortar typically requires curing with water to harden and achieve its full strength. Grout, particularly those based on epoxy or silicone, does not require additional water for curing.