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
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
SUITABILITY OF WATER FOR CONCRETE MIXING OBJECTIVE To assess suitability of water for use in concrete mix. Equipment Measuring cylinder Cube moulds Trowel Tamping rod Vibrating table Testing machine Procedure Analyse water for its chemical compositions as per IS 3025-1964 and compare these with permissible limits given in IS: 456-2000. In case water does not … Read more
FACTORS AFFECTING CHOICE OF CONCRETE FOR A STRUCTURE The choice of whether a structure should be built of concrete, steel, masonry, or timber depends on the availability of materials and on a number of value decisions. 1. Economy Frequently, the foremost consideration is the overall cost of the structure. This is, of course, a function … Read more
TYPES OF DEFECTS IN PLASTER This post describes 7 different categories of defects most frequently noticed in plaster (as mentioned below) Non-structural cracks Structural cracks Debonding Lack of hardness Grinning Expansion Popping The causes and repair methods for each are discussed below. 1. Non-structural cracks Crazing is a network of fine cracks, usually in a … Read more
AIR ENTRAINED CONCRETE A major advance in concrete technology in recent years is the introduction of tiny disconnected air bubbles into concrete called air entrainment. Air entrained concrete results from using either an air-entraining cement or an air-entraining admixture during mixing. Adding entrained air to concrete provides important benefits in both plastic and hardened concrete, … Read more
FLEXURAL STRENGTH TEST OF CONCRETE Objective To determine the Flexural Strength of Concrete, which comes into play when a road slab with inadequate sub-grade support is subjected to wheel loads and / or there are volume changes due to temperature / shrinking. Reference Standards IS: 516-1959 – Methods of tests for strength of concrete Equipment & … Read more
Engineering Properties of Aggregates Aggregates are used in concrete to provide economy in the cost of concrete. Aggregates act as filler only. These do not react with cement and water. But there are properties or characteristics of aggregate which influence the properties of resulting concrete mix. These are as follow. Composition Size & Shape Surface … Read more
Technical Properties of Mortar For the sake of projects, the newly mixed mortar should have good workability, and the hardened mortar should have the required strength, the bending power to the bottom face, little deformation and durability. 1. Workability of Fresh Mortar The workability of fresh mortar refers to the comprehensive properties of mortar easy … Read more