CEN 213 CIVIL ENGINEERING MATERIALS Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS BRICKS Md. Mahfuzur Rahman Assistant Lecturer, Department of Civil Engineering International University of Business Agriculture and Technology (IUBAT), Dhaka Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Lecture Contents Definition of Brick Factors that Affect the Quality of Bricks Constituents of Brick Clay and their Functions Harmful constituents of Brick-Clay Manufacturing Process of Bricks Characteristics of Good Bricks Field Tests of Brick Standard Brick Size Classification of Brick Uses of Brick Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Definition A brick is an artificial kind of stone made of clay whose chief characteristics are a plasticity when wet and stone like hardness after being heated to high temperature. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Factors that Affect the Quality of Bricks Chemical properties of the clay used Preparation of the clay Process of drying Different degrees of burning Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Constituents of Brick Clay and their Functions A good brick-clay should be such a mixture of pure clay and sand that when prepared with water, it can easily be moulded and dried without cracking or warping. Chemical analysis of a good brick-clay should give the following percentage of chemical composition: Constituents % Silica 55% Alumina 30% Iron Oxide 8% Magnesia 5% Lime 1% Organic Matters 1% Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Silica Silica exists in all clays in a state of chemical combination with alumina forming silicate of alumina and some times exists in a free state when it is called sand. The presence of sand prevents cracking, shrinking and warping. The higher the proportion of sand, the more shapely and uniform in texture shall be the brick. But too much of sand makes the brick brittle and weak. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Alumina (Aluminum Oxide) This is the principal constituent of brick clay. It imparts plasticity to clay which is very essential for the purpose of moulding. It also imparts density. But the clay containing too much alumina should not be used because bricks will crack and warp during drying. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Iron Oxide The presence of iron oxide in clay enhances the impermeable and durable qualities. Iron and lime in small quantities give creamy color to bricks. The color of bricks is very much dependent upon the contents of iron and the color ranges from light yellow to orange and red. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Magnesia (Magnesium Oxide) Presence of magnesia in small quantity decreases shrinkage and gives yellow tint. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Lime It reduces shrinkage of bricks during drying and enables the silica to melt in burning and thus binds the particles of brick together. In excess, however, it will cause the brick to fuse too readily and the shape will be lost. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Alkalies and Organic Matter A small quantity of organic matter will assist burning bricks. Excess is bad, because if it is not completely burnt, the bricks will be porous. Small quantity of alkalies will lower the fusion point of clay. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Harmful Constituents of Brick-Clay Iron Pyrites Presence of pyrites causes crystallization and disintegration of bricks on burning. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Harmful Constituents of Brick-Clay Alkalies They are mainly the chlorides and sulphates of calcium, magnesium, sodium and potassium. They produce a dark greenish hue on the surface of bricks on drying. They cause the bricks to fuse, twist and warp during burning. Alkalies in bricks absorb moisture from atmosphere and on drying cause efflorescence. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Harmful Constituents of Brick-Clay Alkalies…. Efflorescence – If soluble salts are present in bricks they absorb moisture from atmosphere and go into solution which appears on the surface in the form of whitish substance as the moisture dries out and the salt crystallize. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Harmful Constituents of Brick-Clay Stone Particles Small particles of stones do not allow the clay to be mixed thoroughly and uniformly. These are harmful to the uniformity of brick texture. These make bricks porous and weak. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Harmful Constituents of Brick-Clay Vegetation and Organic Matter They make the bricks porous and weak because vegetations and organic matter get burnt during the burning of bricks leaving small pores in them. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Harmful Constituents of Brick-Clay Lime If Lime present in excess amount causes the brick to fuse too readily and the shape is lost. Lime in the form of limestone and kankar nodules is very harmful and cause serious troubles to bricks such as it causes the bricks to split and crumble to pieces and deteriorates the quality of a good brick. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Manufacturing of Bricks Different steps are as follows: Selection of brick clay Preparation of brick clay Brick moulding Machine moulding Brick drying Brick burning Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Characteristics of Good Bricks Bricks should be uniform in color, size and shape. They should be sound, hard, well burnt and compact. They should be free from cracks and other flaws such as air bubbles, stone nodules, holes, grit of lime etc. They should not absorb more than 1/5 of their own weight of water when immerged in water for 24 hours (15 to 20% dry weight). The compressive strength of bricks should be in the range of 5000 to 8000 psi. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Characteristics of Good Bricks… The percentage of soluble salts (sulphates of calcium, magnesium, sodium and potassium) should not exceed 2.5% in burnt bricks, because the presence of excess soluble salt causes efflorescence. They should be neither over burnt nor under burnt. Their weight should be generally 6 lbs per brick and the weight per cu ft should not be less than 125 lbs. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Field Tests of Bricks To determine the quality of good bricks: Sound Test: Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Field Tests of Bricks… To determine the quality of good bricks: Strength Test: Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Field Tests of Bricks… To determine the quality of good bricks: Take a brick and try to make mark on the surface by nail. If you can make it, it is not a good brick. If not, it is very hard and compact. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Size of Standard Brick According to P.W.D specification the standard size of bricks in our country is 9.5 ’’ x 4.5 ’’ x 2.75 ’’. This size is most economical. 9.5’’ 4.5’’ 2.75’’ Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Classification of Bricks The following is the classification of bricks by P.W.D. in our country. First Class Bricks Second Class Bricks Third Class Bricks First Class Bats Second Class Bats Picked Jhama Bricks Jhama Bricks Jhama Bats Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE CEN 213 CIVIL ENGINEERING MATERIALS Uses of Bricks Construction of walls of any size. Construction of floors. Construction of arches and cornices. Making khoa (broken bricks of required size) to use as an aggregate in concrete. Manufacture of surki (powdered bricks) to be used in lime plaster and lime concrete. Md. Mahfuzur Rahman, Assistant Lecturer, CE

Md. Mahfuzur Rahman, Assistant Lecturer, CE