This document discusses lime and cement mortar. It defines lime as a cementing material used in construction that binds structural units together. There are three main types of lime: quicklime, hydrated lime, and hydraulic lime. Lime is produced through the thermal decomposition of limestone, then reaction with water. Cement mortar is a mixture of cement, sand, and water used in masonry. The document outlines the selection of materials, proper proportions, and mixing process for cement mortar. It also discusses the properties and common uses of both lime and cement mortar in construction.
3. INTRODUCTION
•Lime is an important cementing material used in engineering construction.
•A Cementing material may be defined as that material which has capacity
of holding structural unit to-geather with sufficient strength.
•Among this group are included lime, natural cements, gypsum, Portland
cement as well as various other synthetic products.
4. •Lime is available in the market in three
main types which are Quick lime, Hydrated
lime, Hydraulic lime
•Classification: based on its composition
i) Quicklime
ii) Hydrated lime
iii) Hydraulic lime
•
CLASSIFICATION
6. Calcium oxide (CaO), commonly known as quicklime or burnt lime is a widely
used chemical compound.Calcium oxide is usually made by the thermal
decomposition of materials such as limestone that contains calcium
carbonate in a kiln. This is accomplished by heating the material to above
825 °C.
CaCO3 → CaO + CO2
Addition of water will lead to the transformation of quicklime into slaked
lime also called calcium hydroxide or portlandite.
CaO + H2O → Ca(OH)2
Result is a paste, called lime putty. In contact with the atmosphere, lime
putty will react following the carbonation reaction.
Ca(OH)2 + CO2 → CaCO3 + H2O↑
MANUFACTURE OF LIME
7. It should possess good plasticity.
It should be flexible and easily workable.
When used in mortar, it should provide greater strength to the masonry.
It should solidify in less time and become hard.
It should comprise of excellent binding properties which adhere to brick or stone
masonry units perfectly.
It possesses high durable properties as it is less shrinkable when used in mortar.
It should be highly resistant to moisture and can be used for pointing works.
All limes must be slaked before use in building construction.
•
PROPERTIES OF LIME
8. Lime is used in the manufacturing of steel in order to remove the impurities.
Soil stabilization for construction of roads, airfields and building foundation
demands lime in large quantity.
Lime slurry is used as mortar for msonry work and for plastering.
Lime is used as an additive in asphalt which helps to improve the property of
cohesion. Lime helps to increase the resistance of asphalt towards stripping
and aging.
USES OF LIME
10. •Mortar is a homogenous mixture of cement,
sand and water. Different types of mortars are used in masonry construction
based on their applications, binding materials, strength, bulk density and their
purposes
INTRODUCTION
11. Selection of Raw Materials
Proportion of cement mortar
Mixing of ingredients
According to ‘Satheesh Gopi’ (Author of Basic Civil Engineering), the
preparation of the cement mortar involves following steps:
PREPARATION OF CEMENT MORTAR
(a) Selection of Raw Materials
Although there are different types of materials available for the
preparation of Cement Mortar, it is necessary to ensure that the right
materials are selected based on the type of construction and its purpose.
The Portland cement is used to make mortar. Ordinary Portland cement is
most suitable for common construction purposes. For making composite
mortars, Lime is also used.
12. Sand must be of good quality and it should be free of impurities like clay,
dust, oxide of irons etc.
It must be cleaned completely before mixing with cement.
Sand provides strength,
resistance against shrinkage and cracking.
It provides bulk to mortars, hence, making it economical. Using just cement
would not only make it extremely costly, but also impractical.
PREPARATION OF CEMENT MORTAR
13. For ordinary masonry work with brick/ stone as a structural unit. – 1:3 to
1:6
Forreinforced brick work – 1:2 to 1:3.
For all work in moist situations – 1:3
For Architectural work – 1:6
For Load Bearing structures – 1:3 or 1:4
The Proportion means the relative quantity of different components to be
mixed to make good mortar, or simply the ratio between different
materials.
Following are the proportions of cement mortar which is commonly
recommended for different works:
01. Masonry Construction:
(B) PROPORTION OF CEMENT MORTAR
14. For External Plaster and Ceiling Plaster – 1:4
Internal Plaster (If sand is not fine i.e. Fineness Modulus> 3) – 1:5
For Internal Plaster (if fine sand is available) – 1:6
For pointing work proportion of cement mortar should be 1:1 to 1:3
For external plaster work, as per Government of India, ‘CPWD
SPECIFICATIONS (VOL.-2)’ (Central Public Works Department), the under
coat shall consist of cement mortar 1:5 (1 cement: 5 coarse sand) and the
top coat shall be of cement mortar 1:4 (1 cement: 4 fine sand) unless
otherwise specified.
03. Flooring Work:
Mortar ratio of 1:4 to 1:8 (cement: sand, water to be judgmental), for 5 to 7
times thickness of verified tiles, should be given as bed between RCC
floor and tiles.
04. Pointing Work:
02. PLASTER WORK:
15. To prepare cement mortar, cement and sand are properly mixed in dry condition.
Water is then added gradually and mixed using a shovel.
The water should be free from clay and other impurities.
Cement mortar can either be mixed manually (Hand Mixing) or mechanically
(Machine Mixing).
For small construction, hand mixing is commonly used. Mechanical mixing is
required when the mortar is needed in large quantities and needs to be used in
continuous order.
(C) MIXING OF INGREDIENTS
16. Well-proportioned and well laid mortar provides an impervious surface.
When water is added to dry mixture of cement and sand, hydration of cement
occurs, and it binds with sand particles and the surrounding surfaces of
masonry and concrete.
A rich mortar of more than 1:3 is prone to shrinkage.
The leaner mix is not capable of closing the voids in sand, and hence the
plastered surface will remain porous.
As per IS: 2260-1981 (Indian Standard), the strength of the mortar depends
upon the proportion of cement and sand. Strength obtained with the various
proportions of cement and sand are as follows.
The important properties of cement mortar are:
PROPERTIES OF CEMENT MORTAR
17. To bind masonry units like stone, bricks, blocks, cement
For Plastering on walls and slabs to make them impervious.
As a filler material in Ferro cement works and stone masonry.
To fill cracks and joints in the wall.
Use of cement mortar gives a neat finishing work to wall and concrete work.
For pointing the joints of masonry.
For preparing the building blocks.
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USES OF CEMENT MORTAR