Common use of Aggregates Clause in Contracts

Aggregates. Aggregate shall comply with British Standard as follows: Fine - B.S. 882 Table 2 Zones 1 to 3 only Coarse - B.S. 882 Table 1 “All in” - B.S. 882 Tables 3 Each type of aggregate shall be obtained from one approved source, capable of maintaining adequate supplies of consistently graded material throughout the Contract. Aggregates for exposed concrete shall be free from all impurities likely to cause discoloration and shall be on consistent colour throughout the work. Fine aggregates and sand shall be clean, sharp, coarse, hard material and equal at all times to the samples, which shall be deposited with and approved by the Engineer. The caustic soda test for organic impurities shall show a colour not deeper than that of the standard solution. The settling test for natural sand shall be made and after being allowed to settle for three hours the layer of silt deposit on the coarse material shall not exceed 10%. The Contractor shall supply all necessary equipment for the testing of fine aggregates and sand for the use of the Engineer. Coarse aggregates shall be hard, clean gravel or broken stone from approved quarries and shall be free from earth, decomposed stone, and extraneous matter. They shall conform to B.S. 882 Table 1 and shall be “Grade Aggregate” 19 mm to 5 mm. Thin, elongated, friable, flaky or laminated pieces; mica or shale shall only be present in such small quantities as not to affect adversely the strength and durability of the concrete. The amount of fine particles occurring in a free state or as loose adherent shall not exceed 1% when determined by the laboratory sedimentation test. After twenty-four hours in water, a previously dried sample shall not gain more than 10% in weight. Each grade of aggregate shall be stored in the works in separate heaps so that there shall be no possibility of any inter-mixing. Any materials which have become inter- mixed shall be removed from the site forthwith by the Contractor. If, in the opinion of the Engineer, the aggregate is dirty or adulterated in any manner, it shall be washed and/or screened by the Contractor to the satisfaction of the Engineer.