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 … Read more
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 … Read more
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 … Read more
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 … Read more
TYPES OF LOADS External loads on a structure may be classified in several different ways. In one classification, they may be considered as static or dynamic. Static loads are forces that are applied slowly and then remain nearly constant. One example is the weight, or dead load, of a floor or roof system. Dynamic loads … Read more
Determine Splitting Tensile Strength of Cylindrical Concrete Specimens Objective: This method covers the determination of the splitting tensile strength of cylindrical concrete specimens Reference: IS: 516 – 1959, IS: 1199-1959, SP: 23-1982, IS: 10086-1982 Theory: Age at Test – Tests shall be made at recognized ages of the test specimens, the most usual being 7 … Read more
Why Beam-Column Joints are Special In RC buildings, portions of columns that are common to beams at their intersections are called beam-column joints (Figure 1). Since their constituent materials have limited strengths, the joints have limited force carrying capacity. When forces larger than these are applied during earthquakes, joints are severely damaged. Repairing damaged joints … Read more
PLASTERING Applying mortar coats on the surfaces of walls, columns, ceiling etc. to get smooth finish is termed as plastering. Mortar used for plastering may be lime mortar, cement mortar or lime-cement mortar. Lime mortar used shall have fat lime to sand ratio of 1 : 3 or 1 : 4. If hydraulic lime is … Read more
THE COMMON TYPES OF PLASTIC Different types of plastics that are used in construction industry are described below. 1. Polyethylene Plastic (PE) Polyethylene plastic is made from the polymerized vinyl monomers. Monomer is a kind of simple compound, which can be polymerized to become macromolecular compound. Three ways are used to polymerize the monomer: high-pressure … Read more
SCAFFOLDS AND LADDERS 1. General provisions Where work cannot safely be done on or from the ground or from part of a building or other permanent structure, a safe and suitable scaffold should be provided and maintained or other equally safe and suitable provision should be made. Scaffolds should be provided with safe means of … Read more