NITTE MEENAKSHI INSTITUTE OF TECHNOLOGY YEHALANKA BANGALORE560064 Department

NITTE MEENAKSHI INSTITUTE OF TECHNOLOGY YEHALANKA, BANGALORE-560064 Department of CIVIL ENGINEERING

LIME Lime is a white caustic alkaline substance consisting of calcium oxide, which is obtained by heating limestone with water.

Composition of lime • The main constituent of lime is calcium carbonate (Ca. Co 3 ) • It is available in nature in the form of limestone , kankar and shells of a sea animals. • Limestone from stone hills is the main source of lime , but shells of sea animals are its purest form. the other constituents of lime stone are as follows: 1. Clay: 8 -30 % 2. Magnesium carbonate : maximum of 30 % 3. Soluble silica : a small quantity 4. Alkalis and metallic oxides : 0 -5 % 5. Sulphates : a small quantity 6. Iron : a small quantity

When limestone is burnt, carbon dioxide is given out and quicklime (Ca. O) is obtained. Ca. CO 3→Ca. O +CO 2 Quicklime is not stable. Water should be poured on quicklime to turn it into calcium hydroxide. This process is known as slaking. During slaking , the following chemical reaction takes place: Ca. O+H 2 O = Ca(OH) 2

�Slaked lime is known as lime in market. �This is used for civil engg construction with sand course aggregates, it reacts with carbon dioxide and exhibits a cementing property. The following chemical reaction takes palace: Ca(OH) 2 + CO 2 = Ca. CO 3 + H 2 O

CLASSIFICATION OF LIME Lime is broadly classified into 1. Fat lime 2. Hydraulic lime 3. Poor lime

1. FAT LIME Fat lime is obtained from burning of limestone, marble, white chalk, seashells, coral… Fat lime is pure lime. It contains about 95 % of calcium oxide. Thus, Impurities constitute hardly 5 %. When water is added, it slakes vigorously and its volume increases 2 - 2. 5 times. Fat lime has the following properties: 1. Its colour is perfectly white. 2. It slakes vigorously. 3. It has a high degree of plasticity. 4. It sets slowly in the presence of air.

Uses of fat lime �Used for whitewashing. �It forms good mortar for brick work and plastering when mixed with sand. �When ground with burnt bricks (surkhi) , it forms good surkhi mortar, which is preferred for building foundations and thick masonry walls.

2. HYDRAULIC LIME Hydraulic lime is obtained by burning of Kankar(ie dug out from the underground sources) Hydraulic lime sets by chemically combining(silica, alumina , ironoxide )with calcium oxide component with water. It contains 5 -30% clay. Its hydraulicity varies depending upon the percentage of clay. Based on this property, Hydraulic lime is classified as: 1. Feeble Hydraulic lime – contains 5 -10 % clay. 2. Moderately Hydraulic lime - contains 10 -20% clay. 3. Eminently Hydraulic lime - contains 20 - 30 % clay. Uses – lime is preferred for making mortar for plastering work

COMPARISON BETWEEN FAT LIME AND HYDRAULIC LIME ITEM FAT LIME Composition Colour Contains less than 5% Contains 5 - 30 % clay Sets in the presence of air Sets in the presence of water Slakes vigorously. Slakes slowly. Increase Volume is increased 2 in volume is marginal 2. 5 times. Pure white Not so white Strength Not so strong Uses For plastering, white washing For making mortar suitable for thick walls and for using damp places Setting Slaking HYDRAULIC LIME

POOR LIME Lime contains More than 30 % Clay is considered as poor lime. It sets very slowly. Its binding property is poor and its colour is dull. IS : 712 -1984 classifies lime into 6 categories from class A to class F as shown below. CLASS A: �It is an eminently hydraulic lime. �It is normally supplied as hydraulic lime. �When mixed with sand in the proportion of 1: 3 and tested for compressive strength after 14 days and 28 days, standard mortar cubes should have a compressive strength of 1. 75 N/ mm 2 and 2. 8 N/ mm 2. �Used for structural purposes like arches and domes.

Class B : �It is a semi- hydraulic lime �It is supplied as quicklime or hydrated lime. �Standard mortar cubed prepared with class B lime and sand in 1: 3 proportion should show 14 days strength as 1. 25 N/ mm 2 and 28 days strength as 1. 75 N/ mm 2. �It is used for masonry works.

Class C: �It is fat lime �It is supplied both as quicklime and hydrated lime. �Used for whitewashing and to give finishing coat to plastering walls. �With addition of pozzalanic, it is used for building masonry works.

Class D: �It contains a substantial amount of magnesium oxide and is similar to fat lime. �It is used for whitewashing and give the finishing coat to plastered walls. is supplied both as quicklime and hydrated lime. Class E: �It is also known as Kankar lime. Lime nodules found in fields or mines are burnt to get this class of lime. It is hydraulic in nature and is used for masonry mortar.

Class F: It is siliceous dolomite lime and is generally used for the undercoat and finishing coats of plaster. �The details of chemical and physical requirements of above classes of limes are given in IS: 712 -1973.

How is lime produced? Carbonation Takes Place Calcium Carbonate Ca. CO 3 Carbon Dioxide Reabsorbed Burnt in a Kiln at 900 o. C Carbon Dioxide Given Off Water Given Off Quicklime Slaked Lime Calcium Oxide Calcium Hydroxide Ca(OH)2 Add to Water Ca. O

Calcium air lime cycle Ca. O Calcium oxide Quicklime T > 900°C + Water Ca. CO 3 Ca(OH)2 Calcium hydroxide Hydrated Lime Calcium carbonate Limestone + CO 2 18

MANUFACTURE OF HYDRAULIC LIME i) NATURAL HYDRAULIC LIME ii) ARTIFICAL HYDRAULIC LIME

MANUFACTURE OF NATURAL HYDRAULIC LIME

MANUFACTURE OF NATURAL HYDRAULIC LIME �There are THREE operations involved in manufacture of natural hydraulic lime: �Collection of Kankar ( preparation ) �Calcination of Kankar ( burning ) �Slaking and Grinding of Burnt Lime ( hydration )

Collection of Kankar • The Kankar is an impure limestone and it is used for manufacturing natural hydraulic lime. • The Kankar is available in TWO forms, namely, » Nodules » Block

Nodules • • The nodules found either on surface of ground or slightly below ground level and easy to collect. • The Kankar in nodular form is considered as superior material for following reasons: ü It can withstand heat and rain without disintegration. ü It contains higher percentage of clay.

Blocks • The blocks of Kankar are found from the underground strata below or on or near the banks of rivers. • The thickness of blocks is usually 50 mm to 300 mm. Both nodules and blocks are quarried with pick-axes & crowbars and its cleaned and converted in to suitable sizes.

Calcination of Kankar �The calcination or burning of Kankar to bright red heat is done either in clamps or kilns as in case of manufacture of fat lime. �Limestone may be burnt in any of the following, i)Clamps ii)Intermittent kilns iii)Continuous kilns

Slaking and Grinding of Burnt Lime • The slaking of hydraulic lime occurs very slowly. • The grinding of quick lime can be carried out in one of the following ways, with the help of » Hand or » Wooden beaters or » Mills working with bullocks or steam power or » Special machines.

Slaking Difference Between Fat Lime and Hydraulic Lime � FAT LIME � The required quantity of water for slaking is added at a time and usage of water quantity is high. � After slaked 1 part of lime is converted into 1 1/2 parts in paste form and 2 parts in powder form. � Time taken for slake is about 3 to 4 hours. � HYDRAULIC LIME • • • The required quantity of water for slaking is added gradually and usage of water quantity is low. After slaked 1 part of lime is converted into 1 parts in paste form and 1 1/2 parts in powder form. Time taken for slake is about 12 to 48 hours.

MANUFACTURE OF ARTIFICIAL HYDRAULIC LIME

MANUFACTURE OF ARTIFICIAL HYDRAULIC LIME • If natural raw material is not suitable for the manufacture of hydraulic lime, it is possible to prepare the hydraulic lime artificially. • Following are the TWO methods of preparing the artificial hydraulic lime: » Conversion of Soft limestone » Conversion of Hard limestone

Conversion of Soft Limestone �The available limestone is in soft as in chalk form and converted in to powder form and mixed with the required proportion of clay. �It is then burnt in a kiln and slaking is carried out as manufacture of natural hydraulic lime.

Conversion of Hard Limestone • The available limestone is in hard then it first burnt and slaked with required proportion of clay to obtain raw material. • This mixture is converted into balls of suitable size and after drying these balls are burnt in kiln. • As this lime is produced after burning twice in kiln, also known as TWICE-KILNED LIME.

MANUFACTURE OF HYDRATED LIME Hydrated lime is a type of dry powder made from limestone. It is created by adding water to quicklime in order to turn oxides into hydroxides. Hydrated lime is most often used to make mortars and plasters. Its chemical name is calcium hydroxide, or Ca(OH) ₂

� Producing dry calcium hydroxide by slaking finely divided or ground, softly burnt lime by carrying out the blending of slaking liquid consisting of 30 to 50 parts by volume water and 70 to 50 parts by volume organic solvent with the lime at a temperature below 45° C. �Subsequently transferring the reaction mixture into a main reaction vessel where the mixture is heated by means of a heating device to a temperature of from 50° to 70° C. �Carrying out the final reaction in another reaction vessel. In the mixing vessel, the ratio of lime to slaking liquid is selected in a way such that a final reaction temperature of 85° to 110° C. is reached in the final reaction vessel.

Fat lime is also known as quick lime, for preparation for fat lime first of all a limestone (calcium carbonate) is taken and calcination is carried out. In presence of atmospheric air it gives quick lime. The obtained bulk stone is grained finely to obtain quick lime powder.

�Pure calcium carbonate from a relatively impure source of calcium oxide, characterized in that the method comprises the steps of slaking the calcium oxide source in water to produce an aqueous hydrated lime slurry. �Treating the slurry by the addition thereto of a water soluble source of anions which anions are capable of forming a salt with calcium ions which salt has a dissociation constant greater than the dissociation constant of calcium hydroxide. �Separating the solid content of the slurry from the liquid fraction content thereof to obtain a substantially solids-free solution of calcium ions and anions. �Intimately contacting the solids-free liquid fraction with carbon dioxide gas at a selected rate to maintain the temperature of the solution within a specific range and to lower the p. H of the solution to a pre-set value conducive for the formation of a precipitate of calcium carbonate in which one of the crystalline forms, selected from the group consisting of calcite, vaterite and aragonite, predominates and separating the precipitated calcium carbonate from the mother liquor.

Lime in conjunction with burnt clay (pozzolana i. e surki and flyash) is used as a material of construction. This mixture possess superior bond. The activated lime pozzolana mixtures are rapid setting, the initial sets being obtained in 1 -2 hr and the final within 24 hr. The mixtures possess high water resistivity and are easily workable.

Cement A Cement is a binder, a substance used in construction that sets and hardens and can bind other materials together. Mixture of Calcareous, Siliceous, argillaceous and other substances Used as binding material in mortar and concrete

Lime Silica Alumina Iron Oxide Gypsum 63% 22% 06% 03% 01 to 04%

Portland Cement Lime Silica Alumina Iron Oxide magnesia Sulphur trioxide Soda and/or Potash 60 to 67 % 17 to 25% 03 to 08% 0. 5 t 0 06% 0. 1 to 04% 01 to 03% 0. 5 to 1. 3%

Hydration of Cement

Hydration of Cement

Hydration of Cement

Why Hydration of Cement is Important?

It is a low cost cement composition that can be admixed with water and hydrothermally closed cured to give acid -resistant products of high compressive strength consisting essentially of, in parts by weight, 1 to 1. 5 parts of a calcium oxide material containing at least about 60% Ca. O, 10 to 15 parts of pozzolanic material containing at least about 30% by weight amorphous silica, and 0. 025 to 0. 075 parts by weight of an alkali metal catalyst and building materials made therefrom as well as the method of making such building materials by closed curing.

Types of cement Ordinary portland cement(opc) Rapid hardening portland cement Quick setting cement Pozzuolana portland cement Low heat cement Blast furnace cement White cement Sulphate resisting cement Coloured cement

Uses of cement It is used in making joints for drains , pipes. It is used to prepare RCC structures of building by using reinforcement with cement concrete. it is used in construction of buildings, bridges, tanks, domes, flyovers, dockyard etc. It is used to prepare cement mortar for building construction works like masonry, plaster, painting, flooring etc. It is used to prepare cement concrete for various construction works.

Types of Cements are considered hydraulic because of their ability to set and harden under or with excess water through the hydration of the cement’s chemical compounds or minerals There are two types: Those that activate with the addition of water And pozzolanic that develop hydraulic properties when the interact with hydrated lime Ca(OH)2 1. Pozzolanic: any siliceous material that develops hydraulic cementitious properties when interacted with hydrated lime. 2. HYDRAULIC CEMENTS: Hydraulic lime: Only used in specialized mortars. Made from calcination of clay-rich limestones. Natural cements: Misleadingly called Roman. It is made from argillaceous limestones or interbedded limestone and clay or shale, with few raw materials. Because they were found to be inferior to portland, most plants switched.

Portland cement: Artificial cement. Made by the mixing clinker with gypsum in a 95: 5 ratio. Portland-limestone cements: Large amounts (6% to 35%) of ground limestone have been added as a filler to a portland cement base. Blended cements: Mix of portland cement with one or more SCM (supplementary cemetitious materials) like pozzolanic additives. Pozzolan-lime cements: Original Roman cements. Only a small quantity is manufactured in the U. S. Mix of pozzolans with lime. Masonry cements: Portland cement where other materials have been added primarily to impart plasticity. Aluminous cements: Limestones and bauxite are the main raw materials. Used for refractory applications (such as cementing furnace bricks) and certain applications where rapid hardening is required. It is more expensive than portland. There is only one producing facility in the U. S.

CEMENTS AND THEIR USES Portland Pozzolana Cement 1. They are used to gain compressive strength with age. 2. They are used to give better workability during preparation of concrete. 3. They have good tensile strength. 53 Grade Cement These cements are used where high early strength in 1 to 28 days are required.

MORTAR

LIME MORTAR

PREPARATION OF LIME MORTAR

CEMENT MORTAR

PREPARATION OF CEMENT MORTAR