Factors Affecting Strength Test Results of Concrete Compressive strength is the most important property of concrete. The compressive strength of concrete is determined in the laboratory in controlled conditions. On the basis of this test result we judge the quality of concrete. But sometimes the strength test results vary so widely that it becomes difficult … Read more
Capping of Concrete Cylinders Capping is required to give a smooth surface for applying compressive load to concrete cylinders. Only cylindrical concrete test specimens are capped using appropriate method. When the ends of cylindrical test specimens are not plane within 0.05 mm, it is required to cap those test specimens. The capped surfaces should be … Read more
Aim To determine volume of concrete per batch, where nominal maximum size of aggregate does not exceed 38 mm. Apparatus Balance – Sensitive to 0.01 kg Tamping bar – Length 38 cm, Weight 1.8 kg Cylindrical mould – Dia = 250 mm, Height = 280 mm, Capacity = 0.01m3 Step by Step Procedure to Calculate … Read more
Sampling of Fresh Concrete To ensure it is representative of the whole truck load, a standard sample consists of scoopfuls taken from different parts of the batch and collected in bucket. Scoopfuls must be taken through the moving stream, as the load is discharged, sampling the whole width and depth (not just the top part). … Read more
Effects of Hot Weather on Concrete Any operation of concreting done at atmospheric temperature above 400C may be put under hot weather concreting. The effect of hot weather may be as follows: Accelerated setting: A higher temperature of fresh concrete results in a more rapid hydration and leads to reduced workability/ accelerated setting. This reduces … Read more
Objective Determination of unit weight or bulk density and void of aggregates. Equipments Name Capacity 1. Balance Sensitive to 0.5% of weight of material 2. Cylindrical metal measure Of 3 litre capacity (for fine aggregate) Of 15 litre capacity (for aggregate upto 40mm) 3. Tamping rod 16 mm dia. and 60 cm long Sample Preparation … Read more
Miniature Stockpile Method The miniature stockpile method is used for reducing all samples of fine aggregates when the material is in damp or moist condition. If the sample to be split is dry, the material is required to be moistened before using this method. Procedure Place the original sample on a clean, dry plate or … Read more
Sample Reduction Using Mechanical Splitter Use of a mechanical splitter is considered to be the best method to reduce the gross sample of aggregate. The mechanical splitter splits the sample into two halves as the material passes through the spaces between the bars in the splitter. The same number of each particle size goes into … Read more
What is Quartering? The process of reducing a representative sample to a convenient size, or of dividing a sample into two or more smaller samples for testing, is called quartering. This is a non-mechanical method of reducing a sample. Steps or Procedure for Quartering Place the original sample in the center of a clean, dry, … Read more
The amount of aggregate sample to be collected is dependent on the maximum nominal size of aggregate. The quantity of aggregate sample should be of such amount, so that the required test can be performed to judge its quality. Sample of aggregate is collected using a sampling scoop. Collect a no of increments (at least … Read more