New approach in measuring water absorption of recycled aggregates

With the increase in the use of recycled aggregate concrete, the demand on recycled aggregate (RA) is escalating. As such, the behaviour and characteristics of RA need to be clearly understood. In practice, the testing procedures of aggregates in Hong Kong follow those laid down in British Standard Institution (BSI) (BS: 812), which provide a good foundation for assessing properties of natural aggregates. As RA may have cement paste attached that may detach from the mass during sample preparation when repetitive soaking in water and drying are employed. Thus, the traditional testing approach for water absorption cannot give accurate results for RA, based upon which, errors in concrete mix designs may result. This paper proposes an innovative method for testing the water absorption of RA named real-time assessment of water absorption. The detailed testing procedure of the new method is illustrated with examples. (C) 2006 Elsevier Ltd. All rights reserved.