Title: Replacement of Natural Sand with Manufactured Sand While Maintaining Packing Density

Author(s): Barbara Aboagye, Ryan Gosselin, William Wilson

Publication: Symposium Paper

Volume: 362

Issue:

Appears on pages(s): 189-201

Keywords: Manufactured sand, natural sand, packing density, intensive compaction tester (ICT), modified central composite design (CCD), response surface methodology (RSM), Fuller-Thompson curve, Funk and Dinger model

DOI: 10.14359/51740883

Date: 6/5/2024

Abstract:
As the worldwide availability of natural sand for concrete continues to decline, attention has turned to manufactured sand obtained from coarse aggregates as an alternative. However, there is still limited information regarding its use in concrete mixtures beyond adhering to standard particle gradation bounds (e.g., CSA A23.1 bounds in Canada). To address the gap, this study presents a central composite design of experiments to analyze the influence of mix proportions on the packing density of concrete mixtures incorporating four types of aggregates: 2 mm sand and manufactured sand, 5-14 mm and 10-20 mm coarse aggregates. The packing density was measured using an intensive compaction tester and results were analyzed using a response surface methodology. The study also included four optimized mix designs obtained using the Fuller-Thompson and the Funk and Dinger methods. Results indicate that a higher proportion of manufactured sand and a higher packing density can be achieved with a particle gradation having a higher proportion of smaller-sized particles. Moreover, the TFA/TA (total fine aggregates/total aggregates) ratio significantly influenced the packing density, whereas the impact of the ratio of 5–14 mm/total coarse aggregates (TCA) was minimal. A prediction model for packing density was developed using multiple regression analysis. These findings provide information on how manufactured sand affects the packing density, which can serve as a foundation for designing concrete mixtures with manufactured sand.