The test for the apparent specific gravity and absorption of coarse aggregate

Abstract

The British Standard test for the apparent specific gravity and absorption of coarse aggregate (B.S. 812: 1951) has been found to give variable results. The present paper describes an investigation made to devise a test that would not suffer from this variability.The factors thought to affect the results of the test were studied, and it has been found that the following modifications to the standard procedure are desirable:I . The size of aggregate tested should preferably be $-k in.The rate of corrosion of cast iron by the action of sulphate-reducing bacteria is increased by the addition of ferrous iron alone or the combined addition of ferrous iron and yeast extract. The addition of yeast extract alone, however, has a retarding effect upon corrosion. The specific action of the added ferrous iron is discussed and the rates of corrosion in heterotrophic conditions are compared with those in autotrophic conditions.

Hydraulic Performance of Lined Permeable Pavement Systems in the Built Environment

“…In line with this, it was observed during tests dry RCA containing the highest fraction of fine material showed the biggest reduction of 8.9% between SC dry and SC moist , a value similar to the 9.4% difference found by Jorge et al [21] on C&D aggregates. However, the level of storage capacities found in this study are in the lower range of what could be expected according to Shergold [15] and Ferguson [16]. This probably reflects the greater C u of the real-life materials (Figure 3) than normally accounted for in open-graded sub-base aggregates, where C u is often below 2 [16].…”