MCU14/0106 Appendix E - Engineering Report

August 2004 -11- 04682104(AB)

 

Table 2: Preliminary Pavement Design Parameters

 

 

 

 

 

 

 

 

Subgrade Material Type’ | _—- Design CBR (%)
Imported Select FILL) 5-15
SAND Be 10

Low to Medium Plasticity 7
(CL-C).CLAY

Medium to High Plasticity, 5
(CI-CH) CLAY _ :

 

Detailed subgrade evaluation should be undertaken during construction following bulk
earthworks to confirm design CBR values. This should include CBR testing and inspection by
Golder Associates.

6.5 General

It is recommended that ‘good’ construction practices are adopted so that moisture variations are
minimised in the high plasticity clays which have an estimated moderate to high potential for
shrink-swell movements. In particular the following recommendations should be followed:-

> Site drainage should be designed to readily remove surface water and to prevent ponding of
water on subgrade areas during construction and also adjacent to foundations and perimeter
slabs once construction is completed.

> Construction methods involving subgrade preparation for earthworks, foundation .
excavation and service trenching should be such that the clay soils are not subjected to
continued exposure, as this may result in excessive drying followed by moisture
readjustment (with associated expansive movements) when areas are overlaid by pavements
or slabs. :

> Trees or moisture drawing shrubs should not be planted in close proximity to movement
sensitive building elements.

Golder Associates