Durability testing of fine grained stabilised soils

Notman, C.F. (2011) Durability testing of fine grained stabilised soils. MPhil thesis, University of Nottingham.

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Abstract

Lime and/or cement stabilised fine-grained soils have been successfully used in the construction industry throughout the UK since the early 1970’s. Soil stabilisation has several economic, technical and environmental advantages. Although the vast majority of roads built upon stabilised soil foundations have resulted in durable pavements, a few case studies exist where expansive reactions have locally occurred, resulting in the requirement for extensive remedial works. Two high profile failures attributed to the expansion of stabilised capping layers were the M40 Banbury IV contract and the more recently constructed A10 Wadesmill Bypass. Both were Department for Transport (DfT) contracts in which the California Bearing Ratio (CBR) swell test was used as part of the quality control and/or investigation procedure. The Highways Agency (HA) and the Transport Research Laboratory (TRL) are still recommending the use of the CBR swell test as a means of determining a soils suitability for use within the stabilised process.

This thesis was undertaken at Nottingham University as part of an MPhil study programme conducted by Craig Notman. The main aspect of the research was to review the CBR swell test (B.S.1924-2: 1990) to determine its suitability as an appropriate laboratory test for assessing a soils volumetric change (as it is, and has been, previously recommended by the HA and the TRL).

The research focuses on the volumetric stability of stabilised soils, which require assessment under laboratory conditions. Various laboratory standards for determining the volumetric stability of stabilised soils were selected for comparative purposes. They included the CBR swell test (BS 1924-2: 1990), the European accelerated swelling test (BS EN 13286-49: 2004) and the loss of strength upon immersion test Manual of Contract Documents for Highways Works, Volume1 (MCHW1) Series 800 Clause 880.4.

When comparing the pass/fail criteria from the three test methods, all three resulted in differing recommendations. The research findings indicate that the pass/fail criterion of the CBR swell test (recommended by the HA74/00) is less stringent than the European accelerated swell test for the same material. That is, when assessing a material’s suitability for stabilisation as a Capping material (foundation class 1: IAN73), the CBR swell test is more likely to deem a material suitable than if the European accelerated swell test was used. The loss of strength on immersion test is the most difficult pass/fail criterion to satisfy.

The author concludes that the BS 1924-1990 CBR swell test is an inappropriate test to be used as the sole determinant for the volumetric stability of stabilised soils (as recommended by TRL505), and that further research is required to develop appropriate guidance before this test is used again for assessing the volumetric stability of stabilised soils.

Item Type:Thesis (MPhil)
Supervisors:Thom, N.H.
Faculties/Schools:UK Campuses > Faculty of Engineering > Department of Civil Engineering
ID Code:2060
Deposited By:Mr C F Notman
Deposited On:31 Aug 2011 11:23
Last Modified:31 Aug 2011 11:23

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