Performance Requirements of Needle Vibrators The operational frequency of vibrator when operated in air (i.e. when not immersed in concrete) shall not be less than 100 Hz and should preferably be higher. For different sizes of needle, the optimum operational amplitude when operated in air, measured in the middle of the vibrating needle should satisfy … Read more
Aim This test method describes the procedure for determining the drying shrinkage or change in length of concrete specimen due to changes in moisture content. Apparatus A length measuring apparatus incorporating a dial gauge capable of measuring the length accurately to 0.005 mm. (see fig shown below) Drying oven capable of maintaining a temperature of … Read more
Properties of Fresh Concrete Concrete remains in its fresh state from the time it is mixed until it sets. During this time the concrete is handled, transported, placed and compacted. Properties of concrete in its fresh state are very important because the influence the quality of the hardened concrete. The fresh concrete has the following … Read more
QUALITY REQUIREMENTS OF COMMON BURNT CLAY BUILDING BRICKS 1. General Quality Bricks shall be free from cracks and flaws and nodules of free lime. Bricks shall have smooth rectangular faces with sharp corners Bricks shall be uniform in colour Frog size of a hand moulded brick having height of 90 mm or 70 mm shall … Read more
Basic Components of a Building A building consists of following basic components. 1. Foundation A foundation is necessary to evenly distribute the entire building load on the soil in such a manner that no damaging settlements take place. Hence, the foundations need to be constructed on good/solid ground. 2. Plinth A plinth is normally constructed … Read more
Tremie Method of Under Water Concreting Tremie method is the most acceptable method of concreting under water. In this method a tremie pipe is inserted in the water up to the point where concrete is going to be placed. Generally the diameter of a tremie pipe varies from 20 cm to 30 cm. Depending upon … Read more
Retempering of Concrete When water is added to a stiffened concrete or partially set fresh concrete in order to bring it back to the desired consistency or workability, then it is called “retempering of concrete’. Importance of Retempering of Concrete The one and only reason for retempering of concrete is to regain the lost workability … Read more
Pile Load Capacity Calculation Using Static Cone Penetration (SCPT) Test Data The safe load capacity of bored cast in situ piles can be calculated using the test data obtained from static cone penetration test as described below. We know that the ultimate load capacity of pile consist of two terms, i.e. End bearing resistance Skin … Read more
Pile Load Capacity Calculation in Weathered or Soft Rock This method of calculating pile load capacity was suggested by Cole & Stroud. Cole & Stroud used ‘N’ values or results of standard penetration tests to find allowable load capacity of the pile in weathered rocks. The formula suggested by Cole & Stroud is given below. … Read more
Guidelines to Follow While Constructing Pile under Water While placing concrete by tremie method, all tremie pipes should be cleaned before and after use. The diameter of tremie pipe should be preferably 200 mm for constructing piles of all diameters within 600 mm. For 25 mm down aggregate, tremie pipe should have a diameter not … Read more