Compare gypsum and cement plaster

We decided to ask the experts if there is a fundamental difference between gypsum and cement plaster, and whether they can be combined. The opinions of the builders turned out to be contradictory, but we were able to draw some conclusions for ourselves. In both cases, we are talking about solutions used to level walls and ceilings, giving them a flat surface. Both gypsum-based compositions and cement-sand mixtures are very popular, being ahead of competitors in many respects, and the choice depends on the characteristics of the premises and other conditions. More about this, but we will start with an analysis of the composition of materials.

Composition of cement plaster

It is possible to talk about the advantages of a particular building material only by studying the composition. The popularity of the cement-sand mixture is explained by many by the fact that it contains available components.

1. 1. Cement. The main binder is cement, the brand of which determines the strength of the solution and the durability of the coating. If M400 cement is used for exterior work and leveling walls in rooms exposed to aggressive environments, then cheaper M150 cement can be used for interior work.

       

 

1. 1. Sand. To give strength and plasticity, different fillers are used, but most often sand is used for these purposes, which differs in origin (river, quarry, alluvial) and fraction. Coarse-grained sand is ideal for road construction and foundation pouring, while fine-grained sand is most often the basis for plaster cement-sand mixtures. Important! Experts do not recommend chasing sand of too fine a fraction, since the plaster mixture prepared on its basis can quickly crack. On the other hand, when using coarse sand, be prepared for the fact that it will take a lot of time to grind the surface, so you need to find your «golden mean».

       

 

1. 1. Water, the amount of which must also be selected in each individual case.

       

 

1. 1. Additives improving plasticity, vapor permeability and other characteristics of the material, and the most accessible of them is lime, but it must be slaked and aged for at least two weeks. If the lime is not cured, undesirable bulges may appear on the surface.

       

 

1. 1. Polymer Additivesimproving the strength of the material and its resistance to aggressive influences, and many builders prefer PVA glue in this matter, and again because of its availability.

       

 

Depending on the features of use and the properties that the plaster mixture should be endowed with, cement and sand are mixed in different proportions, but as a standard, three or four volumes of sand are used for one volume of cement. Looking ahead, we want to say that it is the possibility of experimenting with the quantity and quality of the components used to prepare the mixture that experts consider the main advantage of the cement-sand mortar.

After listening to an alternative opinion, we came to the conclusion that it is not necessary to prepare the cement mixture ourselves, and the quality of modern ready-made mixtures based on already familiar components is a vivid confirmation of this. As an argument for connoisseurs of the «classics», one can cite especially durable polymer-cement mixtures, which are distinguished by resistance to premature abrasion, high resistance to impact and temperature extremes. Among the companies involved in their production, Knauf products are on a special account. These are ready-to-use mixtures used for rough and finish finishing.

The composition and features of gypsum plaster

Gypsum plaster — this is a whole group of ready-made mixtures used mainly for interior decoration of premises with a normal humidity regime. It is easy to guess that the main binder here is gypsum powder. It is obtained from a natural mineral, subjected to pre-heat treatment and crushing. To reduce consumption, give the mixture strength and improve adhesion, natural or synthetic fillers and polymer additives are used.

Gypsum mixtures are supplied in different packaging, they are completely ready for use, for which it is enough to add the right amount of water. The «fat content» of the solution and the scope of its application depend on the amount of liquid. If it is necessary to close a crack in the wall, the amount of water added should be minimal. For finishing (decorative plaster), the solution must be sufficiently liquid and spread well on the wall.

Advantages and disadvantages of cement plaster

A simple analysis of the composition does not give a complete picture and an answer to the question of which plaster mixture is preferable. Practitioners can best tell about it. The advantages of cement-sand mortar, they include:

1. 1. high resistance to high humidity, which underlies the use for outdoor decoration;

       

 

1. 1. high strength of plaster, which, with the correct dosage of components, can serve for a long time, resisting atmospheric and mechanical influences;

       

 

1. 1. the plasticity of the material, and the mixture prepared in advance can be used for several hours;

       

 

1. 1. low cost and availability.

       

 

At the same time, builders talk about the shortcomings of cement plaster, and it does not fit well on concrete, which requires additional surface treatment (etching). Experts also note a long drying time, and the cement mixture must withstand at least two weeks, while for cement to crystallize, the finished mixture must be sprinkled with water for some time. After shrinkage, irregularities may appear, and in order to avoid cracking, heating devices should not be used to dry the premises. The cement mixture is heavy, so it is not suitable for leveling ceilings. The cement has an unsightly gray color, so the facade of the building requires finishing cladding, which takes a lot of time and money.

Advantages and disadvantages of gypsum mixtures

Having assessed the advantages and disadvantages of cement plaster, you can proceed to the study of the properties of gypsum mixtures. Unlike a competitor, they have high adhesion, so they fit perfectly on any surface and do not require additional surface treatment. Gypsum coating does not require additional cladding, as the surface looks perfect.

The consumption of gypsum plaster per square meter of surface is 1.5-2 times lower than in the case of cement coating, and this is a question of the cost of the material. Among the advantages of the cement-sand mixture, many note the low cost compared to the gypsum counterpart, but this issue is debatable, since the price also differs by one and a half to two times, so there is no need to talk about savings. Do not forget that the gypsum coating has good sound and heat insulation properties, unlike a mixture based on cement and sand. But not everything is as good as it turned out with gypsum, so I would like to talk separately about the shortcomings of gypsum coatings:

1. 1. the surface plastered with a gypsum powder mortar is not resistant to mechanical damage, therefore it is absolutely not suitable for finishing facades;

       

 

1. 1. gypsum is afraid of high humidity, and this also underlies the use of the material, and it is recommended exclusively for finishing interior surfaces;

       

 

1. 1. it is necessary to work with gypsum mortar quickly, as it sets quickly, and therefore the mixture is prepared in small quantities, which increases the time for completion of work;

       

 

1. 1. despite high adhesion, additional finishing of concrete surfaces and application of a primer are required if it is necessary to plaster metal surfaces without waterproofing.

       

 

At the construction site, three types of gypsum plaster are used: fine, medium and coarse-grained fractions. The fine-grained mixture is applied in a layer up to 0.8 mm, requires an additional layer, and is used mainly for plastering ceilings. Gypsum plaster of medium-grained fraction, applied with a layer of up to 5 cm, is the main competitor to cement-sand coatings. A large fraction is used to hide significant surface defects, and often for facade cladding, but in the case of good waterproof performance. Rotband gypsum plaster mixtures are very popular.

Gypsum and cement plaster in comparison

A comparative analysis of the characteristics of gypsum and cement-sand plaster suggests that each of them has its own advantages, not without coverage and disadvantages. You can avoid possible troubles by choosing the right material, depending on the features of operation. Outside the building and in rooms with high humidity (bathroom, kitchen), it is definitely better to use cement mixtures, and gypsum is better for finishing inside buildings, which does not require additional cladding.

Useful advice: it is believed that gypsum is afraid of moisture, therefore it is not used for plastering bathrooms, pools, kitchens and other rooms with high levels of humidity. Experts recommend using varnish for this purpose, which is applied on top of the plaster. Such a surface is not afraid of water, moreover, it looks perfect.

Gypsum coating looks more attractive, it is plastic and easy to work with, and it’s hard to argue with that, but if you don’t have plastering skills, then it’s better to learn on cement mortar. Gypsum dries up literally before our eyes (10-15 minutes), while reusing such a mixture is impossible, but this is an indispensable property when leveling the ceiling and hard-to-reach places. For its part, the cement-sand coating dries out only after a few hours, and during this time even a novice specialist can plaster a large area.

Even an experienced builder, having weighed all the pros and cons, cannot unequivocally say whether it is better to use gypsum or cement plaster. With a large number of obvious advantages of gypsum, it should be understood that it is practically not suitable for finishing facades, so there is no alternative to the cement-sand mixture. Meanwhile, working with cement plaster is more difficult, so you can only do the work if you have the appropriate experience. Gypsum mixes are more expensive, but their consumption is less, which also causes certain difficulties in choosing. It is necessary to take into account multiple factors, and in order for understanding to come faster, we have collected all the information presented in a table.

 

Characteristic	Gypsum plaster	cement plaster
Compound	Gypsum powder of different fractions, polymer modifiers	Cement, sand, water, lime and some other additives (as needed)
Drying speed of the finished plaster	2-3 days, and if we are talking about a thick coating — up to 7 days	Two to four weeks (depending on layer thickness, humidity and temperature)
moisture resistance	Low, therefore, when used in rooms with high humidity, the use of protective compounds is recommended	High, so it can be used in the bathroom, swimming pool, kitchen and facade cladding
Shrinkage	Not affected	Within 2mm per 1 meter
Average consumption of material at a layer thickness of 10 mm	10 kg per 1 sq. m.	17 kg per 1 sq. m.

Life hacks: how best to plaster a brick wall

Assessing the advantages of gypsum and cement plaster, our specialists gave some useful recommendations in parallel on how best to plaster a brick wall.

Tip 1

Contrary to the opinion that it is necessary to plaster the walls in cloudy weather, they are sure that it is better for the sun to be, but the air temperature was within 5-30 degrees above zero. It is also a proven fact that plaster dries better in the heat, but this will not benefit the surface, which is guaranteed to crack in the near future.

Tip 2

To improve the strength of cement plaster applied manually or by machine, it is necessary to use a hardener in an amount of 1-2% of the total volume of the mixture. In order for the surface to look perfect, it is necessary to apply a layer of the same thickness over the entire surface.

Tip 3

When asked about the possibility of laying bricks on gypsum plaster, the builders answered unambiguously in the negative. Gypsum has a different composition than the cement mixture used in bricklaying, and it can also be easily removed from the wall surface. It is better to lay a brick on top of cement-sand plaster, while both gypsum and cement mixtures are not suitable for laying ordinary bricks.