1. Pig iron The crude impure iron, which is extracted from iron ores, is known as pig-iron and it forms the basic material for the manufacture of cast-iron, wrought iron and steel. The pig iron is manufactured by the following operations (i) Dressing: Crushed into pieces 25mm, impurities of clay, loam and other earthy matter removed…

Types of defects in timber Types of Defects in timber are grouped into the following divisions. 1. DEFECTS DUE TO CONVERSION During the process of converting timber to commercial form, the following defects may occur. §  Chip mark: mark or sign placed by chip on finished surface of timber §  Diagonal grain: Due to improper sawing of timber §  Torn grain: Due…

Properties of mortar Properties of mortar which are sought for use in masonry are: workability, water retentivity, rate of stiffening, strength, resistance to rain penetration and durability. These properties have been discussed below explaining their effect on masonry. Choice of masonry mortar is governed by several considerations such as §  Type of masonry unit and its…

                             REQUIREMENTS OF FORMWORK Requirements of formwork – quality, safety & economy In the selection of materials for formwork, the three general principles of quality, safety and economy must be paramount. Material quality can ensure safety, and significantly contributes to the achievement of economy. Formwork failure can result in loss of life and always causes catastrophic financial loss. Some general guidelines can…

Brickwork check list for site engineers                                                  Quality of brickwork While on site, a site engineer must ensure that the brickwork is going on as per quality requirements. Some of the general requirements of quality of brickwork are mentioned below. Use this as a checklist while executing brickwork. 1.      The thickness of joint in brick masonry should…

Minimising defects in plastering work Defects in plastering work can be minimised by following the below mentioned techniques. The brick and plastering work should be carried out by skilled masons in the best workmanship manner. Bond of brick work should be properly maintained. Efflorescence is removed by rubbing brushes on the damaged surface. A solution of…

Causes Of Disintegration Of Concrete The primary reasons that cause disintegration of concrete member are described below.                        DISINTEGRATION OF CONCRETE 1. SULPHATE ATTACK Soluble sulphates are present in §  Ground water §  Soil §  Clay bricks Soluble sulphates react with Tricalcium Aluminate of cement I n the presence of moisture and form products which occupy much bigger volume than…

Fire resisting properties of common construction material Fire resisting properties of common building materials such as stone, brick, timber, cast-iron, glass, steel and concrete are mentioned below. 1. STONE The stone is a bad conductor of heat. But it suffers appreciably under the effects of fire. The stone is also liable to disintegrate into small pieces…

Properties Of Aggregates Approximately 75% of the volume of concrete is occupied by aggregates, so quality of aggregates plays an important role in determining properties of concrete.  Aggregates are chemically inert, solid bodies held together by the cement. Aggregates come in various shapes, sizes, and materials ranging from fine particles of sand to large, coarse…

                        Foundation design There are, in foundation design, a number of practical construction problems and costs to be considered. The chief ones are: 1.      The foundations should be kept as shallow as possible, commensurate with climatic effects on, and strength of, the surface soil; particularly in waterlogged ground. Excavation in seriously waterlogged ground can be expensive and…