Composition, proportions and application of cement-lime mortar

Welcome to "All about Concrete," where we explore the principles of building materials to enhance your construction endeavors. Today, we delve into the diverse realm of cement-lime mortar, a vital element in plastering and masonry that is renowned for its workability and durability.

Portland cement’s binding qualities and lime’s plasticity are combined in cement-lime mortar to produce a mortar that works well in a variety of applications. Usually, a carefully balanced mixture of sand, lime, and cement is used to achieve the best results. Because of its exceptional water retention capabilities and ability to work with a variety of substrates, this type of mortar is widely used in both historical restoration and contemporary construction.

To achieve the appropriate strength and workability, it is crucial to comprehend the ratios of cement to lime mortar. Depending on the particular application and the surrounding circumstances, the ratio of cement to lime to sand may change. More cement increases strength and durability, while more lime generally improves workability and adhesion. Achieving the ideal balance between flexibility and bonding strength between mortar and masonry units is crucial.

Cement-lime mortar is used for many different tasks, such as plastering, rendering, and stone masonry in addition to bricklaying. Because of its superior adhesion to non-porous and porous surfaces, it is a highly recommended option for bonding and finishing materials in construction. Cement-lime mortar is the best way to achieve long-lasting and visually beautiful finishes, whether you’re building new construction or repairing older ones.

In this article, we’ll delve into the subtleties of cement-lime mortar and discover how to mix, apply, and cure this adaptable substance. Stay tuned to learn how the perfect combination of strength, flexibility, and dependability in this tried-and-true mortar blend can elevate your construction projects.

Composition Cement-lime mortar typically consists of lime, cement, and sand. Lime provides workability and enhances bonding. Cement adds strength and durability. Sand gives volume and texture.
Proportions The ratio of lime to cement to sand in mortar varies but commonly ranges from 1:1:6 to 1:1:9 by volume. Adjustments depend on specific project requirements such as strength and weather conditions.
Application This mortar is versatile, used for masonry work, plastering, and finishing surfaces. It"s applied with a trowel, ensuring even distribution and adequate coverage. Proper curing enhances its strength over time.

Classification of solutions

Lime mortars are categorized based on the kind of filler used, the quantity of lime used, density, and mechanical and physical characteristics.

Lime mortars are separated into simple and complex categories based on the kind of filler used. A complex mixture also includes sand, gypsum, cement, or clay if a simple mixture only contains lime.

Lean, normal, and fat solutions are distinguished by the amount of lime in them. With a 1:5 ratio between the binder and filler, lean mixtures have the highest concentration of sand, gypsum, or cement and the least amount of lime. Lime content in fat compositions is 50% or higher than that of the filler material. Fatty lime mixtures’ primary benefit is their malleability.

Take note! Significant shrinkage and cracking occur when a layer of fatty solution is approached that is too thick.

The lime-cement solutions are the densest, whereas the gypsum-containing lime mixtures are less dense.

Strength and frost resistance are the two metrics that best describe the mixture’s durability. Lime is the least powerful M4 solution in terms of compression when compared to other brands (like M25, M50, and M75), and these compounds have no effect on frost resistance.

Prepare a lime solution for plastering

Plaster is commonly used for ceilings and walls because it is a relatively simple solution to make. Three steps make up the technological plastering process: spray, soil, and cover (total layer thickness of no more than 25 mm).

Fluff and sifted sand should be mixed in a ratio of 1:3 or 1:4 for splashing, 1:2 for priming, and 1:1.5% for "covering" when preparing a plaster solution. After that, add water and stir, making sure to get rid of any quicklime fragments in the mixture.

Counseling! To facilitate the mixing process, we suggest combining the slaked lime with only one-third of the needed volume of sand and water at first. Then, add the remaining sand and water and mix everything well once more. Additionally, use a watering can rather than a straight stream when pouring the water.

The following is how the slaked lime is made:

  • Put the lump lime in a metal (without signs of corrosion) or wooden container (but not plastic).

Crucial! Choose the container capacity keeping in mind that the slaked lime will increase by three and a half times during the slaking process.

  • Pour cold water over the lime (1 liter of water per 2 kg of slaked lime) and cover with a lid. The boiling process begins.

Crucial! A significant amount of heat is released along with a fairly violent chemical reaction that takes place during slaking. As a result, it is essential to wear boots, rubber gloves, protective clothes, and glasses.

  • After boiling, mix the mixture thoroughly and let the solution sit for 2 weeks.
  • Before direct use, sift dry calcium hydroxide through a construction sieve (to prevent poorly quenched particles from getting into the mixture).

Fluffy compositions offer a variety of benefits.

  • plasticity;
  • antibacterial (especially important when finishing wooden surfaces);
  • relatively low cost;
  • sufficient hardening period.

Advice! We recommend preparing lime mortar for plastering immediately before use. If it hardens: just pour water into it and stir.

The drawbacks of these combinations:

  • Lime hardens slowly: therefore, such a composition begins to “float” after a day.

Advice: Wait until the first layer has fully dried before applying the second layer of the mixture when plastering walls.

  • Lime absorbs moisture well: therefore, it is not recommended to finish rooms with high humidity with mixtures based on it.

Lime-cement mortars

Plastering walls in rooms with high humidity (above 65%) and finishing building facades are two applications where cement-lime mortars work well. Lime gives the mixture good plasticity, and cement, which is a component of the mortar, increases strength, water resistance, and resistance to frost. Because cement is expensive, lime-cement mortar for plastering has a comparatively high cost.

To create a splash, combine sand, cement, and lime in a 2:1:5 ratio. Add water until the mixture resembles thinned-out sour cream. Using a trowel, apply a thin layer of this solution to the wall. It doesn’t need to be leveled.

The following is the algorithm that we use to prepare the composition for the main plaster layer, with a maximum thickness of 50 mm:

  • mix the dry components of the mixture: cement (grade M400) and sand in a ratio of 1:2, 1:3, 1:4 or 1:5 (depending on how heavy the finished finishing solution should be);
  • in a separate container, dilute the lime dough to the consistency of a suspension: to do this, mix the dough and water in a 1:1 ratio;
  • pour this suspension into the cement-sand mixture and mix (moreover, the mass of the suspension is equal to the mass of cement);
  • Continuing to stir, add water until the required thickness is obtained.

After applying the primary layer of plaster to the wall, use the guidelines below to remove any excess, and make sure the level is both vertically and horizontally.

Next, we level it and apply a thin finishing layer with the same composition as spraying.

Speaking of which, For every 25 kg of cement, you will need the following ingredients to make a plastic plaster mortar: 235 kg of sand, 60 liters of water, and 14 kg, or 37 liters, of lime. Moreover, to obtain a sturdy composition: 25 kg of cement, 175 kg of sand, 50 liters of water, and 7.5 kg or 18 liters of lime.

Lime-gypsum mortars

If a composition with a quick setting time is required, make a lime mixture with gypsum (it takes roughly 10 minutes to harden).

  • prepare a regular slaked lime mixture and divide it into two parts;
  • combine the first part with gypsum in a 2:1 ratio and mix;
  • add the second part of the slaked lime mixture to this gypsum mixture and mix again;
  • use the resulting mixture for 5÷8 minutes (while continuing to stir the mixture constantly).

Counseling! It is advised to work quickly and to mix the lime-gypsum solution in small amounts.

Fine grain and non-shrinking are characteristics of such compositions. The fact that they must be used as quickly as possible and that they cannot be used in damp rooms are drawbacks. These mixtures are mostly used for plastering interior spaces; they are rarely used outside.

We explore the foundations of cement-lime mortar in this article from "All about concrete," including its composition, appropriate ratios, and useful uses. A vital component of construction, cement-lime mortar provides durability and adaptability for a range of building projects. Builders can guarantee the best performance and longevity of their structures by knowing its ingredients and the precise ratios required. Understanding the composition and proportions of cement-lime mortar is crucial for achieving strong, durable, and aesthetically pleasing results in construction projects of all sizes, whether it is used for plastering, masonry, or restoration work.

Lime mixture for bricklaying

Lime mortars have a very narrow range of applications in brickwork; they are primarily utilized in the construction of one-story buildings, primarily for interior partitions and low-load walls. Such masonry mortar’s plasticity, low heat conductivity, and strong adhesion are its primary benefits. Low strength (0.4 MPa in compression) and brittleness are among the drawbacks. Lime mortar ready for bricklaying:

  • Mix dry calcium hydroxide and sand in a ratio of 1:3, 1:4 or 1:5 (it all depends on the fat content of the binder).

Counseling! Sift the dry ingredients of the mixture through a fine sieve to prevent lumps in the mortar.

  • Stirring constantly, pour in water in small portions and bring the mixture to a consistency resembling thick sour cream.

The following conditions must be fulfilled by masonry lime mortar:

  • be sufficiently plastic to completely fill all the voids in the bricks and smooth out the unevenness of the seams;
  • be strong enough not to cause deformation of the wall;
  • remain plastic for a long time until hardening.

Cement can be added to the mixture in place of lime. For instance, we mix cement, lime, and sand using M400 cement in the following ratios: 2:1:10 for the M75 mixture and 1:1:8 for the M50 mixture. Composition of cement M300: M75 = 2:0.5:8; M25 = 1:1.7:12. For M200 cement, M75 – 2:0.5:5.

Cement-lime mortar is an adaptable building material that can be used in a variety of construction applications. It is made up of different amounts of cement, lime, and sand to achieve different strengths and properties. Portland cement, hydrated lime, and sand make up the majority of its composition; however, additional additives may be added for particular uses, such as increased durability or workability.

The mortar mix’s performance characteristics are largely determined by the ratios of sand, cement, and lime. Generally speaking, the ideal strength, workability, and setting time of the mortar will determine the cement to lime to sand ratio. For instance, higher cement content results in stronger mortar but may also make it harder to work with; on the other hand, lime increases workability and can help the mortar heal minor cracks on its own.

It’s crucial to use the right mixing and application methods when using cement-lime mortar. It is important to fully blend the dry ingredients in the mortar mix before adding water to guarantee consistency and homogeneity. It is important to carefully monitor the amount of water added in order to attain the appropriate workability of the mortar without sacrificing its strength or durability.

Cement-lime mortar is frequently used for plastering and wall rendering, as well as masonry tasks like stone and brick laying. Because of its adaptability, it can be used both indoors and outdoors and, when properly applied, provides a finish that is weather-resistant and durable.

In conclusion, due to its adaptability, toughness, and simplicity of use, cement-lime mortar is still a basic component in the building industry. Builders and homeowners can both benefit from the composition, proportions, and appropriate application techniques of this material to create sturdy, long-lasting structures that endure over time.

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Anna Vasilieva

Journalist with a technical education, specializing in construction topics. I can explain complex technical topics in simple and accessible language.

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