Bulking of Sand – What, Why & How? After watching this video you will be able to answer following questions. What is bulking of sand? Why bulking happens? What are the factors affecting bulking of sand? How to measure bulking of sand at site? What are the effects of bulking on concrete? How to apply … 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
Impurities in Sand Clay, silt, salts, mica and organic matter are a source of impurities in sand. All sands are generally found to contain some percentage of silt and clay. Mica is easily discernible from its shining surface. A certain percentage of impurities are inevitable in sand; a maximum of 6 % of silt and … Read more
Sand Equivalent Value Test Purpose To determine the percent of undesirable particles in the fine aggregate fraction used in the design of Portland cement concrete mixtures. The method is also applicable for determining the relative proportions of detrimental fine dust or claylike material in soils. Equipment and Materials The Sand Equivalent test kit consists of … Read more
Test for Clay Lumps and Friable Particles Purpose Clay and friable particles may be present in the form of lumps in natural aggregates. If they are near the surface, these lumps can cause pitting under the influence of traffic. Specifications frequently limit these particles to a maximum of 1%. Equipment and Materials Weighing device accurate … Read more
Rodded Unit Weight of Coarse Aggregate Purpose Determination of the unit weight of coarse aggregates in a compacted condition. This test method is applicable to aggregates not exceeding 15 cm (6 inches) in nominal size. The unit weight so determined is necessary for the design of a concrete mixture by the absolute value method. Equipment … Read more
Tests on Aggregate Aggregate plays an important role in pavement construction. Aggregates influence, to a great extent, the load transfer capability of pavements. Hence it is essential that they should be thoroughly tested before using for construction. Not only that aggregates should be strong and durable, they should also possess proper shape and size to … Read more
Aggregates influence the properties of concrete/mortar such as water requirement, cohesiveness and workability of the concrete in plastic stage, while they influence strength, density, durability, permeability, surface finish and colour in hardened stage. Field Tests for Aggregate 1. Surface Moisture Content & Absorption The surface moisture in the aggregate, influences the water cement ratio, strength … Read more
Surface Index of Aggregates Surface index of aggregates is another way to represent the specific surface of aggregate. This method was suggested by Murdock. Murdock provided some empirical numbers to represent the specific surface of different aggregates grading (as shown in the table below). Surface Index Values for Single Graded Aggregate TABLE-1 Sieve Size Within … Read more
Methods of Aggregate Sampling Due to the various sampling locations and the availability of equipment, there are several methods of taking aggregate samples. Uniformity of obtaining the sample cannot be emphasized enough, since it eliminates one variable in test results. The technician must remember that safety comes first. 1. PRODUCTION SAMPLING Bin Sample Sampling the … Read more