FEATURED AUTHOR

Cliff Nicholls

Dr
TRL Limited (retired)

Cliff retired as Senior Academy Fellow at TRL Limited in 2015. He was mainly involved on research into asphalt surface course materials with projects ranging from hot rolled asphalt to surface dressing and including porous asphalt, high-friction surfacings, thin asphalt surfacings and road markings. Cliff was the convenor of CEN TC227/WG1/TG2, asphalt test methods, for 15 years and has worked on several European projects. Cliff has written many TRL reports and other articles.

Subjects: Engineering - Civil, Materials Science

Biography

Cliff was educated at King’s School, Worcester and Imperial College of Science and Technology, University of London.  On leaving university in 1972 he joined Rendel Palmer and Tritton as a graduate engineer.  Initially he worked on steelwork design, including the Merrison check of the south sidespan of the Scotswood road bridge, preliminary designs for a high level crossing of the river Suir at Waterford and the detailed design of a bascule bridge for Benghazi harbour.  Subsequently, he worked on site at the Thames Barrier Project, involved with dredging, temporary works and tremie concrete.
After four years, he left to join Property Services Agency as a project engineer in the Directorate of Post Office Services.  He had responsibility for the structural aspects of about ten projects at any time between inception and completion.  The majority of the structures were reinforced concrete extensions, although some were in steel.  In 1978 he was sent back to Imperial College on detached duty for two years to carry out research into reliability analysis of structures, a mathematical technique to evaluate appropriate safety factors for use in Codes of Practice.
He then joined the Building Regulations Division of DoE as Technical Secretary of UK Eurocode panels with responsibility for receiving comments from interested parties on early draft Eurocodes and developing them into UK comments.  He was a member of the UK delegation to various committees as well as a member of EC Co-ordinating Panel.
In 1983 he joined Building Research Establishment as Head of Materials Section of the Civil Engineering Laboratory at Cardington.  He was responsible for organising the testing of materials for airfield pavements and other civil engineering uses on behalf of Property Services Agency and other organisations. As well as the standard tests on aggregates, cements, bitumens and mixtures thereof, wind-loading tests on roof and wall sections were carried out.  He then moved the Building Research Station at Garston as Head of Concrete Construction Section.  He had responsibility for the Concrete Laboratory as a service unit to other Sections.
In 1986 Cliff joined TRRL (later TRL) as Head of Civil Engineering Section in the Technical Services Unit with responsibility for the accommodation at the Crowthorne site and the provision of civil engineering services for research projects.  After two years, he moved into the research side to work on highway materials, particularly asphalt surfacing materials, for the remainder of his career.  He retired in September 2015 but remains involved on some projects on a standby basis.
The research involved laboratory testing and site trials, with Cliff leading an inspection panel of experts from across the industry to assess the relative performance of different trial sections.  Cliff was heavily involved in the introduction of thin surface course systems in the UK and setting up their approval scheme.  Subsequently, the inspection panel monitored the durability of sections over a nine-year period.
When Cliff joined TRRL, the research was for the Department of Transport but, following privatisation, the range of clients increased.  He has worked on projects for Highways England (and its predecessors), private companies in the asphalt and bitumen industries, the Ministry of Defence, Transport for London and Transport Scotland.  He has also been involved in collaborative research projects for the European Commission and Conferences of European Directors of Roads (CEDR).
Whilst working, Cliff has been involved in British and European standardisation committees.  In particular, he was the convenor of the European task group responsible for asphalt test methods, CEN TC227/WG1/TG2, from 2000 to 2015 during which time nearly fifty tests were published.
During his working career, Cliff has been a member of following professional bodies:
• Institution of Civil Engineers: Member 1976 to 2001; Fellow 2001 to present
• Institution of Structural Engineers: Member 1980 to 2014
• Institute of Asphalt Technology: Member 1990 to 2000; Fellow 2000 to present; Western Branch Chairman: 2002 to 2004; National Council member: 2011 to 2014
• (Chartered) Institution of Highways and Transportation: Member 1994 to 2014
• Society of Chemical Industry (Construction Materials Group): Member 2005 to 2014
• Worshipful Company of Paviors: Liveryman 2004 To 2014
Cliff has also received the following awards:
• 2001: Argent Award for best technical paper in IAT Yearbook
• 2004: Freedom of the City of London
• 2005: SCI Construction Materials Group Award for services to the Group
• 2009: ICE Howard Medal for paper on recycling
• 2012: SCI Distinguished Service Award
• 2015: Paviors’ Medal for lifetime achievement

Education

Areas of Research / Professional Expertise

Personal Interests

Websites

https://trl.co.uk/reports/ROAD+NOTE++RN43

Books

Featured Title

Asphalt Surfacings - 1st Edition book cover

Articles

Compendium of sites and the extent of ravelling

Published: Oct 10, 2016 by DRaT Deliverable D3
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

Data on the performance of sites in the Netherlands, Belgian and the UK with respect to ravelling was reviewed. The findings included significant scatter in ravelling for individual mixtures, higher binder contents and polymer-modified bitumen reduce ravel, slag aggregate and smaller aggregate sizes increase ravelling, ravelling increases with age, the ranking of mixture types for resistance to ravelling is SMA, BBTM, AUTL and then PA.

Correlations between bitumen and asphalt properties – Stiffness

Published: Aug 01, 2016 by FunDBitS Deliverable D2a
Authors: J C Nicholls, J Valentin and L Benešová
Subjects: Engineering - Civil, Materials Science

The correlations between the asphalt stiffness (which can be determined by several methods) and bitumen tests/properties related to stiffness/elasticity behaviour and performance-based characteristics were reviewed. Recommendations were given with respect to future steps and most suitable tests available so far. There is a sufficiently strong correlation between the stiffness modulus of asphalt mixture and complex shear modulus of the used bitumen.

Review of hydraulically bound materials for use in Scotland

Published: Jul 22, 2016 by TRL Published Project Report PPR792
Authors: D Bateman and J C Nicholls
Subjects: Engineering - Civil, Materials Science

The use of hydraulic bound materials (HBMs) for the sub-base layer in Scotland is investigated. The preferred material is the slow setting HBMs although fast setting HBMs show good strength after initial construction but often experience thermal stress cracks. The performance of HBMs can be monitored by extracting cores for analysis and/or by using the Falling Weight Deflectometer.

Best Practice guide for the selection of pothole repair options

Published: Jul 07, 2016 by TRL Road Note 44
Authors: M J McHale, J C Nicholls and I Carswell
Subjects: Engineering - Civil, Materials Science

The principal options for repairing potholes before describing a procedure for selecting an appropriate option for different situations using a series of flowcharts, including default, are defined. Whilst better selection will not affect the generation of new potholes, it should mitigate the effect of those potholes and reduce the potential for them to reappear after maintenance treatment.

Identified correlations between bitumen and asphalt properties (Interim Report)

Published: Dec 31, 2015 by FunDBitS Deliverable D1
Authors: J C Nicholls, J Valentin, L Soukupova, K Mollenhauer, M Tušar, N Bueche, S Bressi, C Karcher, F Batista, M Sá da Costa,
Subjects: Engineering - Civil, Materials Science

An extensive review of existing knowledge available worldwide in the field of bitumen testing, bitumen durability assessment and the relation between bitumen and asphalt mixture properties was undertaken. The results are shown for plenty of technical or scientific papers summarizing their contents and providing basic comments. Particular attention was paid to identifying possible contexts and relationships between the assessments done for the binder and the final composite material.

Review of parameters influencing the propensity of asphalt to ravel

Published: Dec 22, 2015 by DRaT Deliverable D2
Authors: J C Nicholls, J de Visscher, F Hammoum and M Jacobs
Subjects: Engineering - Civil, Materials Science

A literature review into the phenomenon of ravelling (or scuffing or fretting) of asphalt surface course pavements. There are sections on the definition and mechanism of ravelling, the various potential causes of ravelling and strategies for prevention and cure. Some correlations of other asphalt or bitumen parameters with a tendency to ravel have been found. Factors that influence ravelling are materials, mix design, construction and in situ conditions.

Changes in the properties of asphalt mixtures on a trial site after two years in

Published: Oct 28, 2015 by EARN Deliverable D10
Authors: J C Nicholls, S King, C McNally, K Mollenhauer and A Varveri
Subjects: Engineering - Civil, Materials Science

A site trial with four different mixtures containing varying proportions of RA and warm mix additive were laid and monitored for initially, after 12 months and after 24 months for site properties and evaluation of moisture sensitivity with the MIST procedure. The site properties were international roughness index (IRI), mean profile depth (MPD) and corrected SCRIM Coefficient (SC). The results were evaluated for the effect of RA and warm mixture asphalt on durability.

Use of lower temperature asphalt in pavement construction

Published: Apr 22, 2015 by TRL Published Project Report PPR742
Authors: M Wayman, J C Nicholls, and I Carswell
Subjects: Engineering - Civil, Materials Science

A demonstration site with sections of lower temperature asphalt surface and binder course mixtures was laid and monitored for initial properties in order to establish criteria for specifying lower temperature asphalt mixtures. The initial and ongoing performance of the lower-temperature asphalts on the site together with advice on the durability obtained with lower temperature asphalts in the USA and Scandinavia is reviewed.

In service performance of Steelphalt products

Published: Apr 17, 2015 by TRL Published Project Report PPR737
Authors: A Dunford, J C Nicholls, H Viner and P D Sanders
Subjects: Engineering - Civil, Materials Science

A number of sites of different ages with various Steelphalt mixtures were monitored for skid resistance using a Sideway-force Routine Investigation Machine and for visual condition. Samples were also tested in the laboratory using a Wehner-Schulze machine. The conclusion is that Steelphalt products can be used with confidence in non-event situations and could be used in some high risk locations with engineering judgement.

Final report on effects of using reclaimed asphalt and/or lower temperature asph

Published: Dec 15, 2014 by EARN Deliverable D9
Authors: J C Nicholls, S Cassidy, C McNally, K Mollenhauer, R Shahmohammadi, A Tabaković, R Taylor, A Varveri and M Wayman
Subjects: Engineering - Civil, Materials Science

A site trial with four different mixtures containing varying proportions of RA and warm mix additive were laid and monitored initially and after 12 months for site properties and evaluation of moisture sensitivity with the MIST procedure. The site properties were international roughness index (IRI), mean profile depth (MPD) and corrected SCRIM Coefficient (SC). The results were evaluated for the effect of RA and warm mixture asphalt on durability.

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