What Type Of Mortar To Use For Plastering

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If plastering is the only job left in your masonry project, you may be confused by the available mortar varieties. We've composed a list of typical mortar types and their most common applications to assist you.

Among many distinct types of mortar used for plastering, cement is the most common. Generally, the type of plastering mortar will differ by the finish requirements.

When choosing a mortar material, you may also need to consider the durability, climate tolerance, etc. The most common ones include:

  1. Cement mortar
  2. Gypsum mortar
  3. Mud mortal
  4. Lime mortar

Continue reading to learn more about other types of mortar plastering and each ideal application. We will also address some of the common questions that people have. So let's dive right in!

Spreading mortar on the wall, What Type Of Mortar To Use For Plastering

What Is The Purpose Of Mortar?

Mortars aren't just for cement. Other varieties of mortar have distinct purposes in construction. The following is the different types of mortar and their typical usage in masonry project.

Special Purpose Mortar: By Type

Generally, mortar is made by mixing up some special adhesion to ensure quality when applied to their specific application. These will often include:

Fire-Resistant/Refractory Mortar

A refractory mortar is a fireclay with cement and sand that can resist intense heat from fireplaces, ovens, and fire pits. When cured, this substance has great adherence and sets rock hard enough to withstand heat at approximately 3000° Fahrenheit.

In addition, it has calcium aluminate specialized properties making it an ideal heat absorber.

Smoothing out plastering mortar on the house exterior wall

Lightweight Mortar

lightweight mortar is best for vertical and overhead applications, such as rendering walls and pools. It comes pre-mixed, so you don't have to blend powders, it's polymer fortified, and it can be applied up to 3/4 inches on a vertical surface in one lift, saving you a lot of time.

In addition, it is prepared with lime, sand, cement, sawdust, and rice husk.

Sound-Absorbing Mortar

Today, sound-absorbing mortar is the most potent and cost-effective sound-absorbing and noise-reducing substance.

It is commonly used in road tunnels, subway stations, train stations, and underground garages.

X-Ray Shielding/Barite Based Mortar

Adding an extra layer of protection is necessary for places such as medical diagnostic and CT scanner rooms. To deal and interact with X-ray radiation, lowering penetration depth is essential.

Because of the improved shielding capabilities of barite-based mortar, you can use it to render plaster instead of standard sand mortar.

Chemical Resistant Mortar

Chemical resistant mortar is formed by mixing sand, water, and cement/lime right proportions from workable mortar, solidifying after setting and curing the liquid, and producing black strongly crosslinked composites.

A bucket filled with mortar for plastering

Acron is also used in this chemically resistant Mortar, which is highly resistant to corrosive acids and organic solvents such as aromatic and chlorinated ketones.

When constructing walls, a mixture is used to adhere bricks or stones to one another.

What Is The Best Cement Mix For Plastering?

There are two usual methods of determining the cement mortar's exact ratio by volume and weight. However, the right and accurate way of measuring the different aggregates of cement mortar is to measure them in volume.

Cement mortar comprises three vital ingredients sand, cement, and water.

Here below is the account of recommended cement mixing ratios:

The quantity of dry mortar = 1.3 x the amount of mortar wet. The dry mortar is much larger in volume because there's a gap in cement and aggregates.

This is how you ratio the gap value of the ingredients. Also, (part) refers to the type of quantity measurement you prefer, such as bags or buckets, etc.

Therefore, the dry cement mortar mixture volume is 1 x 1.3 = 1.3m3.

The formula for calculating the volume of each ingredient is as follows:

The volume of dry ingredients = Volume of dry mortar x (parts by volume of ingredients / total parts of ingredients)

The volume of dry ingredients = 1.3 x (Parts by volume of ingredients / Total amounts of ingredients)

Quantity Of Cement

Here, to get the total volume of ingredients in the mortar using a 1:6 mix ratio, 6+1 = 7 is the total ingredients. The 1:6 mix ratio is 1 part of cement and 6 part of sand.

Therefore, the volume of cement in mortar = Volume of dry mortar x (Parts of cement / Total parts of ingredient)

Your cement mortar volume = (1.3×1)/7 = 0.185 m3.

Since most cement is available in bags in the market today, the volume of 1 cement bag (50kg) is 0.0347 m3. To convert it into bags, follow the formula below.

0.185 m3 = (1.3×1)/(7×0.0347) = 5.35 of bags.

Quantity Of Sand

Since we know the volume of the dry mortar and how many parts of sand are needed, and the total amounts of ingredients, kindly follow the formula below to get your exact sand volume.

The volume of sand = Volume of dry mortar x (Parts of sand / Total parts of ingredient)

The volume of the sand = (1.3×6)/7=1.14 m3 of sand.

A broken brick wall

Quantity Of Water

The recommended water-cement ratio for wet mortar ranges from 0.4 to 0.6. Furthermore, any admixture added to mortar to improve its workability affects the amount of water required.

Admixtures must be added according to the supplier's instructions.

Therefore, using the same formula to compute the water required is as follows:

The volume of water is = Volume of cement x the cubic meter per 1 bag (1 bag 50kg = 0.0347m3). Use this formula to convert m3 into liter.

What Is The Standard Thickness For Cement Plastering?

Mason spreading plastering mortar on the side of a wall

Determining the standard thickness of cement plastering ensures that your internal and external walls are within the standard defined by the International Code Council (ICC).

In masonry walls, the recommended thickness is 1/2 inch. When put over metal lath, cement plaster materials must be three coats thick and two coats thick when applied over other bases, according to ASTM C91.

Except if it is applied in one layer coat for veneer plaster with a maximum thickness of 3/16 inch.

What Is The Difference Between Type S And Type M Mortars?

Mixing concrete mortar for plastering

Type S Mortar

This type-S mortar is a versatile mortar; you can use this type mortar for high or low-grade masonry work. Additionally, the increased amount of lime mixed enhances its binding ability to withstand extreme moisture.

Furthermore, it is a medium-strength mortar that offers a compressive strength (1800 psi).

Type M Mortar

This mortar type is best for retaining walls and foundation application and has the highest compressive strength at 2500 PSI.

This type of mortar can withstand strong gravity and lateral loads. Type M mortar is also a viable choice for projects involving hard stone.

How Do You Hard Plaster A Brick Wall?

One of the characteristics of brick wall surfaces is water can easily penetrate; in other words, they like to suck water from the outside if left not covered with plaster.

To accomplish the highest level of brick plasterwork, kindly follow these steps below:

  1. Clean your brick wall with a paintbrush to remove dust and debris.
  2. Wear a mask, safety goggles, and gloves before preparing your plaster.
  3. When you're ready, mix your plaster ingredients in a bucket.
  4. Scoop your plaster onto the trowel, resting it on the hawk and tilting it back.
  5. Work from top to bottom, right to left while plastering the brick wall.
  6. Screed the wall once your plaster dries.
  7. Check that the plaster is flat by holding a level vertically along the wall.
  8. Smooth any uneven spots of plaster, and you're ready for drying!

For a visual demonstration, you may want to watch this YouTube video:

To Wrap It Up

Spreading mortar on the wall

Now that you know what type of mortar to use for plastering and knowing the ingredient composition will assist you in deciding which one is the right to use. We hope that this information benefits you in your masonry project.

However, we highly suggest letting the expert do the job for you to attain a high-quality finish job. Also, ensure that your plastering work can sustain the load it will face in the long run.

Made it to the end? Check out these helpful related posts below!

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