How to Choose Cement, Mortars, Plasters and Additives

These products perform multiple functions for the house. They can be used as gripping materials allowing the joining of different elements since once dried they are very solid and resistant. They are also used to fill joints between masonry or ceramic pieces, to build partitions, and to place pavements and coatings.

How to Choose Cement

Plaster, cement and mortar are essential elements in construction or masonry for their strength, cohesion strength and stability.

The same material can offer many different uses: joining pieces such as bricks, covering walls and floors or covering surfaces, waterproofing, isolating and offering decorative use.

Additives can be added to enhance the properties of the material or to give it the aesthetic finish that best suits the house.

Plaster

What is it?

Plaster is a material that hardens quickly when mixed with water and can act as a conglomerate (material that binds, glues or agglomerates other materials). Plaster can be one of the components for forming the mortar

Being permeable to water can only be used inside the house. It is a good thermal insulator, moisture regulator and fireproof (fire-resistant).

Plaster stains are cleaned with hot water and detergent.

What is it used for?

Plaster is generally used in construction to plaster, smooth rough or drip surfaces, cover surfaces such as grooves or open channels on a wall to recess pipes, cables… and for small repairs.

Types of gypsum:

• Strong or masonry plasters are very resistant. They are used in masonry and to make mortars to build partitions or reinforce walls. You can choose between fast setting (indicated for cracks, cracks and urgent repairs) and slow (for inner plasters).
• White or fine plasters are less resistant, are used as finishing material and plastered in, for example, mouldings, panels, internal divisions of the house…
• Textured plasters offer an embossed finish and are used to disguise damage to a surface.
• Plaster: Plaster is a type of plaster. It can be used to create false ceilings and, decoratively, in columns, mouldings and furniture due to its high malleability. Plaster is less porous than other materials and its drying process is faster so it is recommended to make little plaster each time.
• Lime plaster is a mixture of lime and sand. This type is used for the finishing of walls and ceilings. Maybe hydrated or dehydrated
• Perlita is a type of plaster that provides better thermal and acoustic insulation, greater protection against fire, more lightness, more elasticity, better performance and greater acoustic absorption. The final result it offers gives a whitewash-like finish.
• It is also necessary to distinguish between plasters that are applied manually or and those that are applied with the machine. For example, the perlite can be applied mechanically or manually.

Preparation of plaster.

Plaster is mixed with water: one part water per three-quarters of plaster. The setting time (hardening) depends on the density of the gypsum and water mixture that has resulted.

Mortar

What is it?

Mortar is a mass formed by water, sand and conglomerate (material that binds, glues or agglomerates other materials), whether cement, gypsum or lime.

It may contain additives that, added to the mortar in a small proportion, are able to modify and enhance some of its original properties. For example, there are plasticizing additives that improve cohesion and resistance; emulsifiers that improve adhesion for coatings; setting accelerators for plugging waterways; and also waterproofers indicated for applications in facades, basements, wells or swimming pools.

What is it used for?

Serves as grip and bonding material. It is used to join elements such as bricks, create walls and cover surfaces, line walls, repair disconnects… There are also waterproofing and self-levelling mortars to apply on uneven supports.

How is the mortar prepared?

You have to mix the sand and the binder (gypsum, cement, lime) dry. Then a gap is made in the centre and water is added gradually, without stirring. Once the mixture is done, it should be applied for the first hour. You should know that you should not apply a mortar below 5oC or above 30oC.

Tip: If you want a homogeneous mixture you can use a mixer to ensure homogeneity and to facilitate its subsequent application.

1. Mortar components.
2. Concrete components.

How to calculate the volume of concrete needed

Concrete volume x length x width x height

Ex: 10 x 5 x 0.3 m x 15 m3

Types of mortar

There are different mortars depending on the binder:

• Cement mortars are sturdy, hard and waterproof. They are used to build load walls and for bathroom partitions (for their waterproofness)
• Lime mortars are more flexible, easier to apply and highly plastic. They are used to build interior and exterior walls.
• Tail mortars (also called glue cement) are mixed cement and resin adhesives. They are used to fix elements such as ceramic tile and stoneware adhesive indoors and outdoors, in the sand and natural stone. Below we detail its characteristics and peculiarities for its widespread daily use.

Moreover, there are ready-made mortars (which do not need to be mixed with cement, lime, etc.). Within these ready-made mortars we find different classes depending on their use:

• Dry mortar: It is the base mortar for masonry (composed of sand, binders and additives) and is with which bricks are placed.
• Plaster Mortar: Used to level a wall and leave it ready to be painted over and finished in a colour.
• Special mortars: Such as coloured mortars (specially designed to offer a decorative finish) or as specific ones for mounting glass blocks; refractory (which resist fire, ideal for mounting fireplaces, ovens and barbecues); waterproofing (to apply a thin layer of repair and protection in water tanks, swimming pools…); water-repellent; for bindings; for filling; boards; soil levelling mortars; repair (to cover cracks); and single-layer or facade mortars.
• Tail mortar: Glue cement or mortar glue is a cement adhesive, used to fix ceramics and stoneware, concrete, prepared walls, plasterboard, etc. as long as they are not very large parts. It is suitable for both pliers and paving but is not suitable for levelling.

In the case of ceramics, there are different varieties of glue cement depending on the type of ceramic you want to paste (tile, stoneware, porcelain stoneware…), the place of installation (indoor or outdoor) and the type and size of the piece. The type of cement glue also varies depending on the weather conditions to which the ceramic soil is to be exposed: water, heat, ice and thaw.

Therefore, glue cement is classified into two types (C1 and C2) depending on their higher or lesser adhesion:

• C1: Offers normal or basic adhesion. Applies to floors installed indoors. Designed for stoneware floors. Not recommended for large tiles. Its drying time is fast.
• C2: Offers improved adhesion. It is applied both indoors and outdoors. Especially suitable for porcelain floors. This glue cement can be used for tiles of any size. It is applied on underfloor heating, for example, or on floors in contact with water, such as outdoors near swimming pools.

On the other hand, the glue cement must also be chosen depending on the degree of deformability or elasticity that is needed (S1 or S2). The greater the deformability of the glue cement, the greater its ability to compensate for the stresses between the support (surface of the floor on which the tile is placed) and the tile itself.

• S1: Deformable adhesive. Drying time can belong. For example, it is the one used to install underfloor heating floors.
• S2: Very deformable adhesive. Recommended for outdoor use.

Another property of glue cement is their ability to dissolve or reduced slip (specified with the letter T). This prevents tiles from moving once installed and losing adhesion. The T can be accompanied by E, which is the extended open-time (maximum time interval after application of the adhesive, during which the tiles can be placed without losing adhesion).

To apply the glue cement it is necessary that the ceramic piece is dry and clean. A thin layer, less than 0.5 cm, is applied with a flat throughout the ceramic piece and on the surface on which the tile or tile is to be attached.

Cement

What is it?

Cement is a mixture of clay, limestone, gravel and other materials that are mixed with water. It is a thermal, acoustic and electrically insulating material. The resulting paste is fast drying so it must be used immediately. Dry cement is very heavy so it is placed on beams, formwork or columns.

– We have already seen that if the cement is mixed with water and sand the mortar is obtained.

– On the other hand, if cement is mixed with water, sand and gravel, the result is concrete

What is it used for?

It is an essential material in the construction. Its most common use is agglomerate. It is also used for soils where a smooth and unobstructed surface is needed and to make tiles. It can be used in low-temperature conditions as it is an exothermic material (heat releases).

Types of cement

There are different types depending on factors such as drying time (quick-drying ones are used in masonry work that require haste such as a water leak in a pipe…), its flexibility, among others.

• Grey cement is more resistant, are used to make mortars and concrete, and to build all kinds of supports such as beams and columns.
• White cement is less resistant, they are used as finishing material.

Cement can have additives that improve its elastic, hydraulic properties or appearance. It can be pigmented and painted, smoothed and treated.

How is cement prepared?

The cement must be poured slowly and constantly removed to preserve the appropriate thickness and texture.

How to apply these materials?

The surface on which cement, mortar or plaster is to be applied must be clean, dust-free, oil-free, paint or any dirt and also level.

It is very important to respect the drying times recommended by the manufacturer of the product so that the properties of the material do not deteriorate and to achieve a perfect grip.