Aggregate testing using 2nd-, 7th- and 10th-order interpolation polynomials

Owing to the space shortage for land reclamation in Hong Kong, it is difficult to dispose of tonnes of masonry waste generated daily from construction activities. Adoption of recycled aggregate from concrete waste thus becomes a burning issue. The Hong Kong SAR Government has set up a recycling plant in Tuen Mun Area 38 to transform concrete waste into recycled aggregate with practice notes and specifications issued to control the quality of recycled aggregate. This paper studies the relationships of six parameters describing the characteristics of recycled aggregate: (i) particle size distribution, (ii) particle density, (iii) porosity and absorption, (iv) particle shape, (v) strength and toughness, and (vi) chemical composition. Samples of recycled aggregate from ten demolition sites were obtained with the average service life ranging from 10 to 40 years. In addition, one set of samples was specifically collected from the Tuen Mun Area 38 Recycling Plant. The characteristics of these 11 sets of samples were then compared with normal aggregate samples so that recommendations can be made. A Vandermonde matrix is used to estimate coefficients of 2nd-, 7th- and 10th-order interpolation polynomials. From that, mathematical relationships between pairs of tests can be formed, which can be used to simplify aggregate testing processes. This study reveals that there is strong correlation among the parameters, and by measuring two of them: either "particle density" or "porosity and absorption" or "particle shape" or "strength and toughness", and "chemical content", it is sufficient to test recycled aggregate.