Lime is a very popular, widely used material in all kinds of construction. It is precisely because of its wide use in the construction and building materials industry that hydrated lime, also known as hydrate, has been given the common name of building lime. But what is construction lime and what qualities does it possess to make it a high-quality product?
What is construction lime?
Lime is the only binding material which has a closed cycle in nature and its processing is simple. The raw material is extracted from a lime stone deposit and then fired in lime plants. In this process, another form is obtained – quicklime. It is subjected to the process of quenching with water which results in hydrated lime, commonly known as slaked lime. The process of “quenching” with water is carried out in plants in machines called quenchers. Interestingly, nowadays only the finished product in this form, the so-called “dry quenched lime” arrives at building depots, but in the past the process of lime quenching was carried out directly on construction sites. The last stage is the use of building lime directly as an ingredient of masonry and plastering mortars in which, without any chemicals, in a simple and ecological way, hydroxide is changed into the original calcite.
Currently, the main customers for hydrated lime are wholesalers of building materials, manufacturers of dry masonry and plaster mortars as well as sewage treatment plants, waterworks, power plants and others.
Benefits of lime
The use of lime as a building material has a number of advantages, such as:
- beneficial effect on hygiene and microclimate in rooms,
- antibacterial and disinfectant properties – protection of masonry and wall elements against the development of fungi and mould,
- water vapour permeability through the plaster, which eliminates the accumulation of moisture in walls
- better adhesion of mortar to the surface
- increased mortar flexibility,
- reduction of occurrence of salt efflorescence,
- ability to self-heal micro cracks.
What is the composition of Building Lime?
The composition of Building Lime is completely natural. The pure starting material is the simplest and most versatile among binding materials. Therefore, hydrated building lime is a completely natural and ecological product.
Its lime content has a very positive effect on the parameters and properties of building materials. The addition of lime in plasters, mortars, as well as in silicate bricks and post-concrete blocks with a high pH, effectively reduces the possibility of microbial insects and inhibits the development of fungi and moulds. The use of building lime in construction and finishing thus improves the hygienic parameters of the room.
Advantages of Building Lime
When used as an independent mortar component, lime acts as a binding material, but its use as an additional component to cement in mortar makes it possible to exploit other properties of lime. In modern construction, cement-lime mortars are the most commonly used type of mortar. The use of lime in fresh mortar mixes increases plasticity, workability and better adhesion to the substrate – up to twice that of a mix using chemical plasticising additives. On the other hand, hardened mortar mixes provide better crack resistance as in cement mortars. Lime in the mortar composition prolongs the setting time of the material and retains moisture, thus reducing volume changes and the formation of cracks and pores. Lime consists of fine particles, which is what contributes to the material’s flexibility and better water binding properties.
Flexible lime mortars are widely used, for example in seismic and paraseismic areas where only cement-lime mortars are recommended. Furthermore, only in lime-containing mortars is there a self-healing process for micro-cracks. The sealing of the masonry joint is made possible by the movement of the lime into the cracks and the change of form from hydroxide to calcite with a larger volume.
Extremely durable cement-lime plaster
Good quality hydrated lime is a product that meets all the basic requirements for this material, namely durability, resistance and universal application. In masonry, plastering and finishing work a high degree of durability and longevity of the material is required. The durability of cement-lime plaster is estimated at min. 50 – 80 years.
Buildings such as the Great Wall of China, aqueducts in Rome, the Leaning Tower of Pisa, Wawel Castle, etc. bear testimony to the durability of buildings erected using lime mortars which have proved their worth both in climates with a mild climate (e.g. Italy, France, Greece) and in regions with harsh winters (e.g. Poland, Lithuania, Ukraine, etc.).