Proctor & CBR Testing | Soil Mechanics Laboratory

Methodology

Our methodology follows BS 1377:1990, Parts 4 (compaction) and 9 (CBR). For Proctor testing, we prepare soil at varying moisture contents, compact it in a standard mould using a 2.5 kg rammer (4.5 kg for modified Proctor) in three layers with 27 blows per layer. The dry density is plotted against moisture content to determine the optimum moisture content (OMC) and maximum dry density (MDD). For CBR testing, we soak compacted specimens for 96 hours, then penetrate at 1.27 mm/min using a 50 mm diameter plunger, recording loads at 2.5 mm and 5.0 mm penetration. The CBR value is calculated as the ratio of test load to standard load (13.24 kN for 2.5 mm penetration). We also offer Granulometry & Atterberg tests to complement compaction analysis.

Reference Technical Parameters

Local Considerations — United Kingdom

Soil conditions across the United Kingdom vary significantly, from the clay-rich soils of London and the South East to the glacial tills of Scotland and the peatlands of Northern Ireland. In cities like Aberdeen and Bangor, where glacial deposits dominate, compaction characteristics differ markedly from the alluvial soils found in Ashford or Aylesbury. Our team adapts testing protocols to local conditions, ensuring representative sampling and appropriate compaction efforts. For instance, in Barnsley, where coal measures influence soil properties, we often recommend modified Proctor for heavy traffic loading. Our mobile laboratory units serve Basildon and other locations, bringing equipment directly to site for timely results.