Mortar vs Grout | Characteristics, and Types of Mortar and Grout


What is Grout?

Grout is quite viscous fluid or slurry obtain by admixing the cementing or binding materials along with required chemicals, a polymer that increases adhesive property and water so that they can be easily pressurized or flow in a gap space and capillaries.

Thus they are used in reinforcement techniques where there is no easy accessibility to perform the works as the connection of precast concrete, filling cavities in rock and soil, sealing of joints of tiles, etc.

Mortar vs Grout | Characteristics, and Types of Mortar and Grout

Grout is often available in premixed powder form, design with required chemical composition and polymer so that only water is added to form the slurry mix. Sometimes very fine sand is also added to the grout to make grout economical and of desired properties.

During the process of grouting, the air entrained in grout should be avoided. Grout shouldn’t contain any amount of lime, this is because lime has a high amount of swelling and shrinkage on variations of water.

The expansion on grout due to gas generation must be avoided. Grout can be compressed and pressurized in the cavities but cannot support the pressure or load in absence of such enclosed space or cavity.

Thus, they only prefer to use over enclosed space and voids not in open space. Before moving toward Mortar vs grout, let see some characteristics.

Characteristics of Grout

  • Grout is quite a viscous fluid that has high flow property and hydraulic efficiency.
  • There is no segregation and bleeding in the grout. They form dense slurry at the time of use.
  • Grout has high strength development after their hardening.
  • Grout has noncorrosive property due to the absence of aggregates.
  • Grout doesn’t contain lime, so they don’t expand and swell.
  • Grout has high water content during its wet form. So it doesn’t require curing for countering heat of hydration.

Types of Grout

  1. Cement grout
  2. Bituminous grout
  3. Bentonite grout
  4. Chemical grout
    1. Epoxy grout
    1. Furan resin grout
    1. Polymer grout
    1. Silicone grout

Uses of Grout

  • Use for ceramic tiles: The joint space between ceramic tiles is sealed with help of Grout by pressing it in joint with help of metal plates and trowels. And also, for the renovation of the tiles that have trapped air pockets while placing, the grout is pressurized by forming drill holes in tiles.
  • Use to infill cavities: The minute cavities in any structure can be filled by grout by pressing it through pipes or nozzles.
  • Use to stabilize the soil: The soil with low bearing capacity is grouted with help of cementitious mix or Bentonite slurry.
  • Use to infill the joints and cracks in rock: The rock bed with very weak joints containing many fractures and joints are grouted before use. This is generally adopted in the tunneling process.

What is Mortar?

Mortar is a thick plastic paste formed by a mix of cementing or binding materials (clay, cement, lime) along with the sand, water, and sometimes admixture with the purpose of sticking or spreading over the surface so that it can adhere over it and also can adhere two surfaces.

Mortar vs Grout | Characteristics, and Types of Mortar and Grout

They have very low water content n comparison to grout and thus have a very little or negligible amount of flow. Due to this, they can support their own weight along with some additional weight over it even in open space.

The plastic property of weight mortar enables easy molding or casting too. They don’t get much structural strength after hardening. They required curing at least for 7 days.

Characteristics of mortar

  • Mortar in the wet state has very good plastic property, thus has great workability. Sometimes even plasticizers are used to decrease the workability decreasing water content.
  • Mortar can be spread up to thin( 10-20mm) layer even over vertical surfaces
  • They have the capabilities of binding two material like stone, brick, concrete blocks
  • On excessive mixing and water content, they tend to segregate
  • They have the property of efflorescence due to more lime content
  • The strength of mortar is relatively low.

Types of mortar

  1.  Lime mortar
  2. Cement mortar
  3. Clay mortar
  4. Surkhi  and Bajra  mortar

Uses of mortar

  • Use as binding material in masonry works
  • Use to create the shotcrete: Shotcrete is the pressurized spray of the mortar over the surface of the tunnel or retaining slopes for higher stability.
  • Use for the wall jacketing and retrofitting along with the reinforcement bars and wire mesh
  • Used for plastering.
  • Used for creating different shapes of corbels and cornice.

Now, let us see summary of Mortar vs grout below.

Mortar vs grout – Difference between Mortar and Grout

StateThey are viscous fluid states or slurry states in the earliest form and thus have extremely hydraulic flow properties.They are plastic thick paste state. Thus have great plastic property and low flow property
WorkabilityDue to their slurry state, they are hard to handle on hand. Thus have less workability and are only pressurized through the injection or trowels in cavities They are only to be work with a cavity or enclosed space as they cannot sustain themselves in free open spacesThey have very good plastic property thus have high workability to work with hand.     They can be worked on open surface and also in enclosed surface to some extent
Water contentThey have an extremely high water contentThey have relatively low water content
UsesUse for the reinforcement works and sealing purposeUse for general masonry construction, surface treatment
Strength and durabilityThey have high structural strength and are targeted for more durabilityThey have comparatively low strength and durability.
Lime contentThey shouldn’t contain lime.The lime is sometimes added to make mix.
Sand contentVery small amount of sand (sometimes) or almost no sand it many groutHigh amount of sand than binding material
PermeabilityGrout have very less permeability after they hardenThey are porous, so gave high permeability
CuringNo curing is requiredCuring is required at least of 7 days.

I hope this article on “Mortar vs grout” remains helpful for you.

Happy Learning – Civil Concept

Contributed by,

Civil Engineer – Rajan Shrestha

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