Introduction

This video presentation from 1998, depicts a site at Weston-Super-Mare, Somerset (Principal Contractor - HBG), where subsoil stabilisation works, to engineer soils (with an inherently low bearing capacity - average natural CBR value of untreated soils was in the region of 2%) for use as capping replacement materials, with a CBR value of 15%.

Soils can also be treated for use as sub-base replacement materials, where the design matrix can produce a processed material which is non-susceptible to frost.

The opening scenes on the presentation show brief excerpts from various process stages - excavations in the mainly dense cohesive candidate clays (with Plasticity Index ranging from 13% to 36%), the spreading of binders, soil mixing, compaction and trimming/grading to level.

The site formation to the car parks, to be treated, in this instance to a depth of 250mm, was prepared by the earthmoving contractor, either by excavation to reduce levels and/or by filling to make up levels, and was then compacted to seal the surface, prior to being made available for stabilisation.

The subsequent stabilisation process was carried out in the following stages:

Stage 1 - Lime spreading

Stage 2 - Rotavating lime

Stage 3 - Checking depth of mix and MCV (Moisture Condition Value)

Stage 4 - Levelling back to tolerance

Stage 5 - Second phase rotavating

Stage 6 - Re-trimming to tolerance

Stage 7 - Cement spreading

Stage 8 - Rotavating and MC (moisture content) adjustment

Stage 9 - Compaction

Stage 10 - Final trimming to tolerance

Stage 11 - Bitumen Curing Membrane

Stage 12 - End product testing