Cement-lime Mortar: Proportions And Technical Characteristics Of 75 Mortar And Finished Masonry Grade 50

2024 Author: Beatrice Philips | [email protected]. Last modified: 2024-01-18 12:09

Over the past decades, the use of cement-lime mixtures in construction and finishing has remained at the same level. But this is not due to a lack of new materials and technologies, but only because this composition meets all modern requirements for building materials. Cement-lime mortar remains relevant and in demand.

Main advantages

Cement-lime mortar is a durable and plastic material that is excellent as a binder for construction and for finishing work.

• It can be used as masonry mortar or plastering material. In the form of a masonry mixture, it reliably connects blocks or bricks used in construction. As a plaster, it can be used for interior and exterior finishing works.
• It is excellent for casting monolithic floors due to its characteristics. Lime, which is part of the solution, increases the period of its hardening. An increase in the setting time and viscosity of the composition allow you to avoid the formation of cracks, help to more evenly distribute the putty over the surface.

Penetrating ability

Cement mortar with lime has a high degree of adhesion to the surface. It is able to easily fill small cracks and depressions, which increases the adhesion strength to any materials to which it is applied.

Such a solution is characterized by a high degree of adhesion, so it can be used even when working with wood. Plastering on shingles (wooden crate) is made with just such a solution.

The increased characteristics of strength, elasticity and moisture resistance make it possible to use the mixture for any finishing work indoors, even with high humidity, since dampness and precipitation do not destroy the finished coating. The mortar can be used, for example, for finishing work in bathrooms, on facades or on foundations, even in that part of it where it directly adjoins the blind area and, as a result, is exposed to moisture.

Specifications

The composition of such a solution necessarily includes cement, sand, slaked lime and water. It is worth paying attention to the fact that it is necessary to add slaked lime. Otherwise, the quenching reaction will begin in the solution itself when water is added, and bubbles, forming already inside the solution, will lead to cracking of the plastered surface. This process of bubble formation will lead to a deterioration in the quality of the solution and to brittleness after it dries.

Due to the lime that is part of the material, pathogenic bacteria and fungi do not develop on it, in addition, lime prevents rodents and various pests from entering the home.

Building mixtures, their composition and properties are regulated by various GOSTs . This is necessary for the standardization and regulation of building codes. GOST 28013-98 is the main regulatory legal act governing the technical requirements for mortars and materials included in the composition.

This standard also includes the characteristics of quality indicators, acceptance rules and conditions for the transportation of ready-made solutions. It contains the qualitative and quantitative characteristics of masonry mortars, materials for plastering and for interior work, used in various operating conditions.

Properties

The main properties of cement-lime mortars:

• mobility;
• the ability of the solution to retain water should be from 90%;
• the delamination of the prepared mixture should be up to 10%;
• application temperature up to 0 degrees;
• average density;
• humidity (this parameter is used only for dry mortar mixtures).

The composition of the mixture is selected depending on the type of material on which it will be applied, and on the conditions for further operation of the finished coating.

There is such a thing as the fat content of the finished mixture. Fat content depends on the amount of astringent included in the composition.

Cement-lime mortars are divided into three categories of fat content

• Normal - these are solutions with such plasticity, which is most universally suitable for use in various conditions. In solutions with such a fat content, shrinkage and, as a result, cracking of the finished coating do not occur.
• Skinny Are mortars with minimal shrinkage. They are ideal for tiling work.
• Fatty - These are mixtures with a high degree of plasticity, which is due to the large number of binders included in the composition. This material is best used for masonry work.

The fat category can be adjusted by adding components to the composition that can change the plasticity of the solution. For example, porous sand reduces fat content, while lime, on the contrary, can increase it.

Thus, you can easily adjust the plasticity of the finished solution and adjust its properties for specific operating conditions.

Density and grades

The components that make up the cement-lime mortar have a direct effect on its density. Also, the ratio of these components has an important effect.

As a result, solutions of the following types can be distinguished:

• low density or light - up to 1500 kg / m³;
• high density or heavy - from 1500 kg / m³.

Also, according to the ratio of components, solutions are divided into grades from M4 to M200 in accordance with GOST 28013-98. For example, mortars of the M100 and M75 brands are best suited for masonry. They are characterized by high levels of moisture resistance and strength. The components that make up these materials are more homogeneous, since, unlike concrete of similar grades, they do not include crushed stone.

Ready-made mortar of grade 100 or grade 75 is suitable for the construction of civil and industrial facilities . To prepare solutions of these brands, it is necessary to mix cement, lime and sand in a certain proportion. So, for M100 mortar when using cement grade 500, the proportions will be 1: 0, 5: 5, 5. And for M75 mortar using a similar cement brand, the proportions will already be different - 1: 0, 8: 7.

For plastering works, M50 and M25 mortars are very popular. They have such undeniable advantages as cheapness and ease of preparation.

Solutions of grade 50 and grade 25 can be used at indoor humidity above 75% . This allows them to be used in the construction of baths and other premises where high humidity persists for a long time. Also, the lime included in the composition prevents the formation of any kind of fungus on the plastered surface, which, of course, is the advantage of such a coating.

Diversity

Plaster mixes can be divided into several types.

• Basic - are used for the initial, rough leveling of the surface and the sealing of large flaws and holes;
• Decorative - such options may contain decorative additives such as pigment for coloring, crushed mica to create a shimmering effect, plasticizing and hydrophobic additives;
• Special - are used to improve the technical properties of the treated premises, they can serve for moisture-proof, sound-proof and heat-insulating tasks.

Dry mix or do-it-yourself composition?

The indisputable advantage of this material is its cost. It is significantly cheaper than a cement-sand mortar with a similar application. The benefit is due to the economical consumption when applied to various surfaces in comparison with the analogue. Sandy mortar is less plastic due to the scattered fraction of sand and the absence of a plasticizer. It has less adhesion and is less well distributed over the surface.

Cement-lime mortar can be purchased as a dry mix from various manufacturers, or you can make it yourself. Now there is a wide selection of manufacturers of ready-made mixtures with their own characteristics and areas of application.

You should pay special attention to the labeling on the packaging to find the optimal mix suitable for the type of work you need.

To use such a mixture, add water in accordance with the instructions on the package, mix thoroughly to obtain a uniform texture. For these purposes, you can use a construction mixer or, in the old fashioned way, knead the composition with a trowel and shovel.

In the event that you decide to make the mixture yourself, then this is not difficult to do. It is enough to purchase all the necessary ingredients (cement, lime, sand) and mix them in the proportion of the appropriate brand that you want to get.

When making a cement-lime mortar, it is necessary to add slaked lime, but if you only have quicklime available, you can extinguish it yourself.

Lime slaking method

This procedure must be carried out in compliance with safety precautions, wearing gloves, goggles and a mask.

• In a metal bowl in which you plan to extinguish lime, they place quicklime and water in a 1: 1 ratio, in that order.
• After the end of boiling of the mixture, which is accompanied by a violent quenching reaction, more water must be added so that it completely covers the material.
• The contents of the container are mixed and covered with a lid.
• The lime container should be left alone for 14 days. The process of making slaked lime is not so much laborious as long.

It is up to you to make a choice in favor of buying a ready-made mixture or preparing a solution with your own hands . But when making this or that decision, it is better to weigh the pros and cons of such an act in advance, because the manufacturers have done most of the work, and you will only have to seal the solution.