tran.157.3.143.pdf (199.85 kB)
A philosophy for a performance specification for road foundations
journal contribution
posted on 2008-09-08, 08:32 authored by C.D.F. Rogers, Paul R. Fleming, Matthew W. FrostThe road foundation layers perform several functions
both during construction and when the road is in service,
for example load-spreading, temporary haul routes, and
a base for the overlying construction layers. The critical
loading condition is usually directing trafficking where
the applied stresses are greatest. The capping and subbase
layers during construction require adequate
stiffness and strength to resist these stresses. The
current UK specification for road foundations is based on
a recipe approach, and, unless permission is granted to
use an analytical design, the pavement foundation
designs are based entirely on the California Bearing
Ratio (CBR) to characterise the subgrade, capping and
sub-base materials. Here CBR is used as an index of both
material strength and stiffness, although it measures
neither directly. Such an approach is potentially
inefficient and does not readily facilitate the use of new
and marginal materials or alternative design procedures.
Recent technical advances in laboratory and in situ
testing of pavement foundation materials now allow the
performance parameters of stiffness, strength and
resistance to permanent deformation to be measured
both for design and during construction. This in turn
enables a performance-based specification for road
foundation layers to be introduced to provide some
assurance of the as-constructed quality, and by
permitting the use of secondary or recycled aggregates,
to contribute to the parallel goal of sustainable
construction. This paper sets out an idealised philosophy
for a performance-based specification for road
foundations, examines the individual elements of the
specification in relation to current knowledge and makes
recommendations for a phased introduction alongside
CBR-based methods.
History
School
- Architecture, Building and Civil Engineering
Citation
ROGERS, C.D.F., FLEMING, P.R. and Frost, M.W., 2004. A philosophy for a performance specification for road foundations. Proceedings of ICE, Transport, 157 (3), pp. 143-151 [DOI:10.1680/tran.157.3.143.41181]Publisher
© Thomas TelfordPublication date
2004Notes
This is a journal article. It was published in the journal, Proceedings of ICE, Transport [© Thomas Telford] and is also available at: http://www.thomastelford.com/journals/ISSN
0965-092XLanguage
- en