Here in this we are going to cover the topics like Lime definition and meaning, uses of lime in construction and types of lime in civil engineering.
Let’s first begin to throw light on the uses and then definition and meaning of lime for construction.
Use of Lime in Construction Work
Here are the uses of lime in construction work:
- Due to its high availability, lime is very popular in construction and has many uses. In this area, it has found the broadest application and can serve for radically different end tasks.
- Lime is extracted from natural rocks in which carbonate is present. Such rocks include shell rock, limestone and chalk.
- Processing of minerals takes place in a furnace at high temperatures of about +1290 ° C. After this treatment, the rock turns into pieces of lime, of a wide variety of sizes. In most cases, the resulting pieces of lime are crushed to small sizes. Lime may contain in its composition a small amount of impurities, which contain mineral additives and clay.
- Whitewashing of various elements. Lime is diluted with water, and a wonderful building mixture for whitewashing is obtained. This mixture can be used to whitewash walls, ceilings and other elements both inside buildings or premises, and outside. Lime-bleached areas are bright white. Due to the fact that inside the building the influence of external environmental factors is not as intense as outside, therefore, inside the lime painting lasts for a rather long time, compared to painting on the streets. Very often, the walls of the basements are whitewashed with lime, which in turn disinfects the basement and gives it a clean and well-groomed appearance. Such popularity of the use of lime is due to its low cost and sufficient durability.
- Wall plasters. During the plastering of the walls, quicklime plays the role of an additional binder component;
- In the production of bricks. In the process of producing sand-lime bricks, a dry construction mixture is used, where quicklime is used as an additive;
- As a component for insulation. Inexpensive heaters, in which lime is used as one of the components, allow filling the voids during finishing work;
- To improve the elasticity of mortars. The addition of lime to mortars significantly improves their elasticity and adds comfort during use.
The main advantages of lime are as follows:
- Low cost;
- The constancy of its properties under the influence of external factors;
- Antiseptic effect;
- Environmental friendliness;
- Wide application.
In any situation during construction, if possible and appropriate, use building materials and mixtures made on the basis of lime, this will not only save your financial resources, but also protect your health.
Definition & Meaning of Lime
As a rule, lime all over the world is conventionally combined by the general term products of roasting (and subsequent processing) of limestone, chalk and other carbonate rocks.
Most often, under the name “lime” they mean quicklime CaO and the product of its interaction with water – slaked lime Ca (OH) 2 .
Depending on the chemical composition, it is divided into building air lime, which mainly consists of calcium and magnesium oxides, and hydrated lime, which contains a significant amount of silicon, aluminum and iron oxides.
In construction, lumpy and powdery lime are distinguished. Powdered lime is divided into:
- ground quicklime,
- slaked fluff lime (obtained by slaking calcium, magnesian and dolomite lime with a limited amount of water).
Other types of lime are soda lime and bleach.
Quicklime is a product of calcination of limestone rocks, where calcium oxide CaO is the main chemical component that actively interacts with water with the further formation of Ca (OH) 2 .
Building lime is a chemical substance where calcium and magnesium oxide, in varying proportions, are the active components of the mixture. Due to the interaction of the compound with water, slaked lime is obtained, a white powder, which is poorly soluble in water.
Types of Lime in Civil Engineering
When chemical analysis is made on lime, they generally have the chemical properties of the raw material. Lime is composed of calcium oxide or calcium hydroxide depending on the main substance. However, they contain small amounts of magnesium, Mg, silicon, aluminum and iron.
If there is a small amount of clay mineral in the lime raw material, the color of lime is darker than other lime types. The extinction process of this lime is longer. Since the demand in the market is low, its production is low and at the same time its efficiency is low. 1.0-1.5 m3 of quicklime is obtained from one ton of quicklime.
Here are the types of lime in civil engineering:
It is a lime composed of calcium oxide or hydroxide that hardens slowly in air by reacting with atmospheric carbon dioxide. Since they do not have hydraulic properties, they generally do not harden under water.
Air limes produced by calcination of limestone or dolomitic rocks and contain mainly calcium oxide and magnesium oxide. When hydrated lime interacts with water, they react exothermically. The quicklime is placed on the market in the form of large chunks called heads or ground fine powder.
They are quick lime composed mainly of calcium oxide.
They are quick lime composed mainly of calcium oxide and magnesium oxide. Lime obtained by firing dolomite stone at a temperature of 900-1000 C is called dolomite lime.
It is air lime formed by controlled quenching of quicklime with water and mostly composed of calcium or magnesium hydroxide. Slaked lime does not react exothermic in contact with water. Slaked limes are produced as dry powder or pulp.
Hydrated Calcium Lime:
They are mainly lime containing calcium hydroxide, magnesium hydroxide and magnesium oxide.
Semi-Hydrated dolomitic lime:
They are mainly hydrated lime that oxidize calcium hydroxide and magnesium.
Fully hydrated dolomitic lime:
Hydrated dolomitic lime containing mainly calcium hydroxide and magnesium hydroxide.
It is slaked lime produced by calcination and quenching of shells.
It is the slaked lime obtained as a by-product in the production of acetylene in calcium carbide. Carbide is formed as a result of the reaction between limestone and coke in arc furnaces. In arc furnaces, reaction occurs around 2000C temperature. Carbide emits acetylene gas (C2H2) during contact with water. These limes are preferred not to be used indoors because of the irritating odor and burning.
It is a dough-like slaked lime that contains or does not contain magnesium hydroxide and is mainly composed of calcium hydroxide, which is produced by mixing with water to reach the desired consistency.
Hydraulic Lime and Natural Hydraulic Lime:
They are lime produced by burning and quenching and grinding clayey-sandy limestone or mixing suitable materials with calcium hydroxide and containing mainly calcium silicate, calcium aluminum and calcium hydroxide.
These have the properties of solidifying and hardening under water. Atmospheric carbon dioxide contributes to the hardening process. They contain at least 3% free lime by mass.
Hydraulic lime produced in powder form by burning high and low clay-sandy limestone and quenching by grinding or not grinding are called “Natural Hydraulic Lime” (NHL).
Lime with suitable pozzolanic or hydraulic materials up to 20% by mass is called NHL-P. Organic additives are added to all HL and NHL types.
Testing on Limestone
The following practical tests are carried out on limestones to determine their suitability:
- Physical test
- Heat test
- Chemical test
- Ball tees
Pure white limestone. Hydraulic limestones are bluish gray, brown or medium dark in color. Hydraulic lime gives off a nice smell. They have clayey tastes. The presence of lumps indicates quick lime and unburned limestone.
A piece of dry stone weighing W1 is heated in an open fire for several hours. If the sample weight after cooling is W2, the weight loss is W2 – W1. Loss of weight indicates the amount of carbon dioxide. From this amount the calcium carbonate in limestone can be processed.
A teaspoon full of lime is placed in a test tube and dilute hydrochloric acid is poured into it. The contents were stirred and the test tube was kept in the container for 24 hours. A feeling of fatigue and a slight residue indicates pure limestone. If the effervescence is less and residue is more then it indicates impure limestone. If a thick gel is formed and after the test tube is placed upside down it is possible to identify the class of lime as shown below:- Class A chalk, if the gel does not flow.- Class B chalk, if the gel tends to fall.- Class C chalk, if there is no gel formation.
This test is performed to identify whether the lime belongs to class C or class B. By adding about 40 mm of sufficient water, the size of the chalk ball is made and is not disturbed for six hours. Then the ball is placed in a basin of water. If within minutes slow expansion and slow disintegration begins, it indicates class C lime. If there is little or no expansion, but only cracks appear it belongs to class B lime.
Hope you find this article helpful, check out our other articles on civil engineering:
- Principles of Building Planning in Civil Engineering (Explained)
- Types of Wood Used for Building Houses
- 12 Tools That are Used for Stone Masonry Works
Thanks for reading our blog on types and uses of lime in construction.