Engineers Australia

A comparison of inferred CBR test results on ‘Perth Sands’

Stephen Flux

Abstract

This paper presents a comparison of inferred California Bearing Ratio (CBR) results obtained from a 4.5 kg Clegg Hammer, 20 kg Clegg Hammer, Perth Sand Penetrometer (PSP) and Dynamic Cone Penetrometer (DCP). Fieldwork was undertaken on four occasions at three locations within the Perth metropolitan area, namely at Preston Beach (Safety Bay Sand), Muchea (Colluvial Sand), and twice at Cockburn (engineered fill and Tamala Sand, the name of the sand derived from the Tamala Limestone). CBR values were inferred and the results from the different pieces of field equipment compared. Overall, at the locations tested, the 4.5 kg Clegg Hammer gave results that produced higher inferred CBR values, whilst the PSP inferred lower CBR values, with the CBR values inferred from the DCP and 20 kg Clegg Hammer in between.