Abstract

MUJTABA, H; FAROOQ, K; SIVAKUGAN, N  and  DAS, B M. Laboratory and field investigations in granular soils to correlate relative density, relative compaction and grain size. J. S. Afr. Inst. Civ. Eng. [online]. 2020, vol.62, n.2, pp.12-21. ISSN 2309-8775.  http://dx.doi.org/10.17159/2309-8775/2020/v62n2a2.

An attempt has been made to correlate relative density and relative compaction based on laboratory and field test data. In this investigation, 185 sandy soil samples were tested in the laboratory. The experimental investigations include classification tests, maximum and minimum density tests, and standard and modified Proctor and in-situ density tests. The values of the dry unit weight of these samples obtained by performing different tests fall between 14.7 kN/m³ and 20.8 kN/m³. Based on these results, linear and multivariate regression analyses were carried out to (a) relate relative compaction and relative density, (b) relate maximum (e_max) and minimum void ratios (e_min), and (c) express e_max and e_min in terms of median grain size (D₅₀) and uniformity coefficient (C_u). Experimental and predicted values varied ± 5%, with a 95% confidence interval for the relation between relative compaction and relative density, and for other relations the variation was ± 10%. The proposed equations were validated using a new data set which had not been used for the development of the correlations. Proposed equations were also compared with equations presented by various other researchers. Validation of the proposed equations suggests that these equations may be used for future prediction of the respective variables.

Keywords : relative density; relative compaction; void ratio; uniformity coefficient; curvature coefficient; effective grain size; median grain size.

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