Aggregate is one of the basic constituents of concrete. Its quality is of considerable importance because about three-quarter of the volume of concrete is occupied by aggregates. One of the physical properties of aggregate that influence the property of concrete is the grading of aggregate. The grading of aggregate defines the proportions of particles of different size in the aggregate. The grading of fine (size < 5 mm) and coarse (size > 5 mm) aggregates are generally required to be within the limits specified in BS 882: 1992.
The objective of this experiment is to obtain the grading curve for both fine and coarse aggregate.
1. Balance - balance or scale used in testing fine and coarse aggregates shall have readability and accuracy as follows: For fine aggregate, readable to 0.1 g and accurate to 0.1 g or 0.1 % of the test load. For coarse aggregate, or mixtures of fine and coarse aggregate, readable and accurate to 0.5 g or 0.1 % of the test load. 2. Sieves – the sizes and apertures appropriate to the specification of the material being tested, complying with BS 410: For coarse aggregate, standard sieve size of 50.0 mm, 37.5 mm, 20.0 mm, 14.0 mm, 10.0 mm, 5.0 mm and 2.36 mm (Fig. 2C1-1). For fine aggregate, standard sieve size of 10 mm, 5.00 mm, 2.36 mm, 1.18 mm, 600m, 300 m and 150 m (Fig. 2C1-2). 3. Mechanical Sieve Shaker -a mechanical sieving device, used to create vibration of the sieve to cause the particles to bounce. 4. Oven - an oven of appropriate size capable of maintaining a uniform temperature of 105°±5°C.
1. Representative sample was chosen by quartering (according to BS 812: Part 102: 1984) or by use of a sample splitter (Fig. 2C1-3). The sample to be tested should be the approximate weight desired when dry. For this experiment, about 500 grams of fine aggregate was weighed. 2. The samples was dried to constant weight in the furnace at a temperature of...