Cliff  Nicholls Author of Evaluating Organization Development
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.

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

Areas of Research / Professional Expertise

    Asphalt materials (and the tests to assess them) including:
    - Hot rolled asphalt (HRA)
    - Porous asphalt (PA)
    - Thin surface course systems (TSCS) which include SMA, BBTM and AUTL

    Other highway materials including:
    - High friction surfacings
    , Road marking materials
    - Concrete

    Reliability analysis for the calculation of partial safety factors.

Personal Interests

    Cliff was a keen oarsman and still takes out his scull for a gentle outing. He has been a licensed umpire and still regularly officiates at regattas and head of the river races.
    Cliff is a member of four bridge and plays most weeks with different partners at each of them.
    He likes to visit historic houses and museums with his wife, and will also her preferences of visit gardens and art galleries as well.

Websites

Books

Featured Title
 Featured Title - Asphalt Mixture Specification and Testing - 1st Edition book cover

Articles

DRaT Deliverable D3

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.

FunDBitS Deliverable D2a

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.

TRL Published Project Report PPR792

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.

TRL Road Note 44

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.

FunDBitS Deliverable D1

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.

DRaT Deliverable D2

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.

EARN Deliverable D10

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.

TRL Published Project Report PPR742

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.

TRL Published Project Report PPR737

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.

EARN Deliverable D9

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.

EARN Deliverable D7

Laboratory study on moisture and ageing susceptibility characteristics of RA and


Published: Nov 27, 2014 by EARN Deliverable D7
Authors: A Varveri, S Avgerinopoulos, T Scarpas, J C Nicholls, K Mollenhauer, C McNally, A Gibney and A Tabaković
Subjects: Engineering - Civil, Materials Science

Site trials of asphalt mixtures both without and with reclaimed asphalt (RA) were laid and cored 24 h and 12 months after construction for laboratory testing. The testing to investigate the effect of RA on the moisture damage susceptibility of the asphalt mixtures was undertaken without further ageing and following laboratory ageing. The results were compared.

EARN Deliverable D4

Report on the results of laboratory tests for the RA mixtures after field ageing


Published: Nov 27, 2014 by EARN Deliverable D4
Authors: A Varveri, S Avgerinopoulos, T Scarpas, J C Nicholls, K Mollenhauer, C McNally, A Gibney and A Tabaković
Subjects: Engineering - Civil, Materials Science

Site trials of asphalt mixtures both without and with reclaimed asphalt (RA) were laid and cored 12 months after construction for laboratory testing. The testing to investigate the effect of RA on the moisture damage susceptibility of the asphalt mixtures was undertaken without further ageing and following laboratory ageing. The results were compared with those obtained from samples cored 24 h after construction.

TRL Published Project Report PPR695

Filling potholes and making local repairs using Roadmaster® vehicle


Published: Jul 30, 2014 by TRL Published Project Report PPR695
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

A review of the Roadmaster® technology was undertaken including a survey of the durability that has been achieved for repairs undertaken with the equipment. Following inspections of one-year old repairs by Roadmaster® spray injection patching repair system together with some additional evidence, the technique looks ideal for carrying out localised repairs to pavement surfaces including filling potholes, joints, cracks and open areas.

EARN Deliverable D3

Effects of constituent materials, recycled and secondary sources materials and c


Published: May 13, 2014 by EARN Deliverable D3
Authors: K Mollenhauer, J C Nicholls, A Varveri, A Tabaković, C McNally and A Gibney
Subjects: Engineering - Civil, Materials Science

The parameters affecting the durability of road materials and the service life of pavements were listed and evaluated for conventional asphalt materials. The durability effects of asphalt mixture composition as well as the use of additives and or recycled materials were considered. Durability effects were found which can be implemented to LCA and/or LCCA calculations.

EARN Deliverable D2

Report on the results of the laboratory tests for the RA mixtures without consid


Published: Feb 28, 2014 by EARN Deliverable D2
Authors: A Varveri, S Avgerinopoulos, T Scarpas, J C Nicholls, K Mollenhauer, C McNally, A Gibney and A Tabaković
Subjects: Engineering - Civil, Materials Science

Site trials of asphalt mixtures both without and with reclaimed asphalt (RA) were laid and cored 24 h after construction for laboratory testing. The testing to investigate the effect of RA on the moisture damage susceptibility of the asphalt mixtures was undertaken without ageing and following laboratory ageing.

TRL Published Project Report PPP666

Specification for Low Temperature Asphalt Mixtures


Published: Jul 21, 2013 by TRL Published Project Report PPP666
Authors: J C Nicholls, H Bailey, N Ghazireh and D H Day
Subjects: Engineering - Civil, Materials Science

The types of specification that are used for hot mix asphalt are discussed and a series of documents drafted to cover low temperature asphalt mixtures are attached as appendices. The appendices are modelled on the current European standards, supporting national guidance documents and the Specification for Highway Works clauses.

TRL Published Project Report PPR656

Reducing congestion on the road network: Part 3 Early strength gain (rapid cure)


Published: Apr 19, 2013 by TRL Published Project Report PPR656
Authors: J C Nicholls and J M Prime
Subjects: Engineering - Civil, Materials Science

A series of different cementitious mixtures, some with admixtures to accelerate the early-life strength gain, at different ages after curing at two different temperatures were manufactured and tested. Site visits were also made that revealed rapid-cure concrete is not always delivered even specified. Early strength gain (rapid-cure) reinstatement materials were produced but not to extent that was desired.

TRL Published Project Report PPR598

Review of Iterlene ACF 1000 as a bitumen regenerator for hot asphalt mixtures


Published: Mar 09, 2012 by TRL Published Project Report PPR598
Authors: J C Nicholls and J Prime
Subjects: Engineering - Civil, Materials Science

Information on Itelene ACF 1000, a regenerator used rejuvenate the binder, is reviewed and further tests undertaken to assess the effectiveness of the product. It was found that the regenerator does recover the properties that have degenerated in aged bitumen for their incorporation into a new asphalt mixture.

POTHOLE Deliverables 1 & 2

Definition of the term “pothole” and selection of test and evaluation methods fo


Published: Jan 31, 2012 by POTHOLE Deliverables 1 & 2
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

Based on the responses of a questionnaire circulated around Europe, a definition of “pothole” was proposed and existing pothole repair materials and techniques reviewed. The principal requirements of the materials that need to be assessed in order to ensure durability were identified as the standard properties plus compactibility in adverse conditions, setting time before traffic, sensitivity to conditions, adhesion and recyclability. Available test methods were also identified.

TRL Published Project Report PPR535

Asphalt durability tests: Part 1, Widening the applicability of the SATS test


Published: May 12, 2011 by TRL Published Project Report PPR535
Authors: J R A Grenfell, G D Airey, A C Collop, R C Elliott and J C Nicholls
Subjects: Engineering - Civil, Materials Science

Alternative parameters for the Saturation Ageing Tensile Stiffness (SATS) test were investigated to make the procedure less aggressive for lower stiffness materials. A suitable parameter combination for a SATS test for specimens made from 40/60 pen bitumen was found to be 85 °C temperature, 0.5 MPa pressure and 24 h duration.

TRL Published Project Report PPR536

Assessment of asphalt durability tests: Part 2, Comparison of wheel tracking tes


Published: May 12, 2011 by TRL Published Project Report PPR536
Authors: J C Nicholls, J P Harper, K L Green and J M Prime
Subjects: Engineering - Civil, Materials Science

Comparative studies have been undertaken using the wheel track test using the CEN small and large devices plus the old UK method in two laboratories and two methods of compaction: roller and vibratory. The results showed unexpected outcomes of the inability of the large size device to deal with mixtures having limited deformation resistance and the effect of air voids content on the deformation resistance of EME2 mixtures.

TRL Published Project Report PPR537

Assessment of asphalt durability tests: Part 3, Review of SATS test to evaluate


Published: May 12, 2011 by TRL Published Project Report PPR537
Authors: J C Nicholls J Harper K Green and R C Elliott
Subjects: Engineering - Civil, Materials Science

An investigation was carried out into whether the Saturated Ageing Tensile Stiffness (SATS) test can assess the remaining service life of existing asphalt layers. Tests using the current protocol and two variants were undertaken on cores that showed that some discrimination may be possible when supported by results from other, simpler, tests, by validating a layer that was known to be imperfect.

TRL Published Project Report PPR547

Review of Saturation Ageing Tensile Stiffness (SATS) test for use in Ireland


Published: Mar 04, 2011 by TRL Published Project Report PPR547
Authors: J C Nicholls, J Prime, B Meitei and A Lowe
Subjects: Engineering - Civil, Materials Science

Available literature on the saturation ageing tensile stiffness (SATS) test was reviewed and tests undertaken on samples manufactured from aggregates covering the main aggregate types used in Ireland were tested. Both the 15/25 pen bitumen specified and the more widely used 40/60 pen bitumen were used. Little benefit was expected if the test were incorporated into the Irish Specification for Road Works when using native aggregate sources.

TRL Report TRL674

Durability of thin surfacing systems. Part 4 Final report after 9 years moniting


Published: Dec 02, 2010 by TRL Report TRL674
Authors: J C Nicholls, I Carswell, C Thomas and B Sexton
Subjects: Engineering - Civil, Materials Science

The visual condition, SCRIMtex and recovered binder properties were monitored for 3 years at sites with thin surfacing systems. Results from a total of 137 sites were analysed with the findings indicating that, if a thin surfacing system is in a good condition after 1 year in service, it will be serviceable for at least 5 years and the typical life of a thin surfacing system is about 10 years, depending on the type of thin surfacing and the condition of the substrate.

TRL Insight Report INS007

Increasing the environmental sustainability of asphalt


Published: Jun 25, 2010 by TRL Insight Report INS007
Authors: J C Nicholls, I Carswell, M Wayman and J M Reid
Subjects: Engineering - Civil, Materials Science

The environmental sustainability of asphalt requires measures to improve its durability, reuse reclaimed asphalt and incorporate secondary materials. Durability minimises both the environmental impact of and traffic disruption caused by subsequent maintenance; recycling also improves environmental sustainability; and the incorporation of secondary material has great potential. These measures are described and the resulting life-cycle implications considered.

TRL Road Note RN43

Best Practice Guide for Recycling into Surface Course


Published: Mar 24, 2010 by TRL Road Note RN43
Authors: I Carswell, J C Nicholls, I Widyatmoko, J Harris and R Taylor
Subjects: Engineering - Civil, Materials Science

A guide as to what is considered to be good practice when specifying, designing, producing and applying the incorporation of suitable reclaimed asphalt in thin surfacing materials is offered in provided. A method of designing the asphalt mixture taking into account the binder content and binder properties of the reclaimed asphalt is included together with more general advice on the changes needed in the different operations.

TRL Report TRL672

Review of Shell Thiopave™ sulphur-extended asphalt modifier


Published: Oct 02, 2009 by TRL Report TRL672
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

A review of laboratory tests and site trials with sulphur-extended asphalt in a pelletised form, Shell Thiopave™, were reviewed. The technical properties that are achieved with mixtures incorporating it at rates of between 20 % and 40 % by mass of the binder were assessed.

Report on Phase 1 of the BiTVal Project

Analysis of Available Data for Validation of Bitumen Tests


Published: Jan 24, 2009 by Report on Phase 1 of the BiTVal Project
Authors: J C Nicholls (editor)
Subjects: Engineering - Civil, Materials Science

In order to define the performance-related requirements for paving binders, any relationships found between binder and asphalt properties reported in literature. A database, covering publications of the identified bitumen properties and their relationship to asphalt properties and/or road performance, was set up and searched for correlations with the asphalt performance for permanent deformation, stiffness, low temperature cracking, fatigue cracking and adhesion.

TRL Road Note RN42

Best practice guide for durability of asphalt pavements


Published: Jul 18, 2008 by TRL Road Note RN42
Authors: J C Nicholls, M J McHale and R D Griffiths

General guidance on the procedures for maximising the durability of asphalt pavements is given which, whilst not be practical in all circumstances (particularly emergency repairs), should be used as ideals that are strived for whenever practicable. The guidance and advice included encapsulates the overall concepts.

TRL Report TRL666

Durability of continuously reinforced concrete surfaced with asphalt


Published: Jun 25, 2008 by TRL Report TRL666
Authors: K E Hassan, J C Nicholls, H M HArding and M E Nunn
Subjects: Engineering - Civil, Materials Science

The aim was to develop designs for a durable long-life continuously reinforced concrete pavement (CRCP) with a low-noise asphalt surfacing. The performance of selected CRCP slabs, with and without a thin asphalt overlay, was compared with a continuously reinforced concrete road base (CRCB) with a 100 mm asphalt overlay. The ability of various TSCSs to bridge cracks and to prevent reflection cracks from the underlying CRC slabs was also undertaken on laboratory-produced specimens.

TRL Report TRL660

Durability of thin asphalt surfacing systems. Part 3: Findings after six years


Published: Jul 19, 2007 by TRL Report TRL660
Authors: J C Nicholls, I Carswell, C Thomas and L K Walter
Subjects: Engineering - Civil, Materials Science

The results from SCRIMtex, visual assessment and recovered binder properties were measured for selected sites witth thin surfacing systems for 3 years and analysed with data from the previous 3 years. The findings showed that, if a thin surfacing system is in good condition after 1 year in-service, it will be serviceable for at least 5 years and probably in excess of 8 years. The typical life can be over 10 years, depending on the system type and the condition of the substrate.

TRL Report TRL659

Cement Kiln Dust (CKD) as a filler in Asphalt


Published: Jan 10, 2007 by TRL Report TRL659
Authors: J C Nicholls, J M Reid, S D Whiteoak and M Wayman
Subjects: Engineering - Civil, Materials Science

Two laboratory studies were undertaken, one using five different mixture types manufactured both with cement kiln dust (CKD) and limestone filler and one, concentrating on workability and water sensitivity, with the composition of three sources of CKD. A pilot-scale trial was laid for both binder and surface course mixtures with and without CKD as filler. CKD can be successfully used as the added filler in routine asphalt mixtures.

TRL Published Project Report PPR187

Test procedures for durability and adhesion in asphalt


Published: Jan 08, 2007 by TRL Published Project Report PPR187
Authors: J C Nicholls and C D Whiteoak
Subjects: Engineering - Civil, Materials Science

A programme of laboratory tests that incorporated variants of the saturation ageing tensile stiffness (SATS) procedure was undertaken to support the CEN ad-hoc group on adhesivity. The aim was to try to measure the durability of adhesion and cohesion in the asphalt mixtures. The findings of that programme together with the main conclusions that can be drawn from it are given.

TRL Report TRL656

Implications of implementing the European asphalt test methods


Published: Sep 14, 2006 by TRL Report TRL656
Authors: J C Nicholls, C Roberts and P Samuel
Subjects: Engineering - Civil, Materials Science

Each test called up in the Specification for Highway Works was reviewed asainst the harmonised European Standard that will replace it and categorised as being Identical, Related or Distinct. Comparative trials were undertaken on the tests for texture depth of pavements, storage stability of modified binders and wheel-tracking of asphalt mixtures to determine any changes needed to the numerical values of associated requirements.

TRL Report TRL655

Asphalt surfacing to bridge decks


Published: Sep 14, 2006 by TRL Report TRL655
Authors: J C Nicholls, R W Jordan and K E Hassan
Subjects: Engineering - Civil, Materials Science

A literature search, a questionnaire and a laboratory test programme into waterproofing systems on concrete bridge decks overlaid with different thicknesses of asphalt were undertaken. The laboratory test programme identified some differences in their properties that have been used to identify the basis for specification. A secondary test programme was undertaken specifically to look at tests for measuring the flexibility of asphalt materials.

TRL Report TRL645

Feasibility of recycling thin surfacing back into thin surfacing systems


Published: Sep 25, 2005 by TRL Report TRL645
Authors: I Carswell and J C Nicholls, R C Elliott and J Harris
Subjects: Engineering - Civil, Materials Science

Trial sites were laid with up to 30 % recycled asphalt (RA) in the new asphalt mixture. The visual condition, density, texture depth, grading, recovered binder and resistance to permanent deformation were monitored. The suitability of aggregate suitability and calculation of maximum theoretical amounts of RA that can be added were also undertaken. The findings demonstrated that 10 % RA can be easily added to new materials but greater care is needed at great proportions.

SAMARIS Deliverable D23

Procedures for identifying hazardous component in materials for asphalt


Published: May 21, 2005 by SAMARIS Deliverable D23
Authors: J C Nicholls, V Mouillet, B Koenders, F Deygout and P Samuel
Subjects: Engineering - Civil, Materials Science

Research was undertaken unto tests for identifying hazardous aspects of secondary and/or recycled component materials. Such materials need undergo a wide range of investigations to check their suitability, from simple to extensive, because of the distinct properties of the material at source. A procedure was developed around two known hazardous component materials and four more general situations with suitable tests being identified to check for them.

TRL Report TRL606

Durability of thin asphalt surfacing systems. Part 2: Findings after three years


Published: Aug 01, 2004 by TRL Report TRL606
Authors: J C Nicholls and I Carswell
Subjects: Engineering - Civil, Materials Science

The results from SCRIMtex, visual assessment and recovered binder properties were measured for 3 years and analysed for selected sites with thin surfacing systems. The findings show that, if a thin surfacing system is in good condition after 1 year in service, it will be serviceable for at least 5 years and probably in excess of 8 years. The typical life of a thin surfacing can be in excess of 10 years, depending on the system and the condition of the substrate.

SAMARIS Deliverable D7

State of the art for test methods to detect hazardous components in road materia


Published: Apr 26, 2004 by SAMARIS Deliverable D7
Authors: J C Nicholls, M Clark and P Samuel
Subjects: Engineering - Civil, Materials Science

The increased use of both secondary aggregates and recycling in the asphalt industry has increased the need to assess the health and safety hazardous, if any, of such components. The known hazards that occur, even if only under extreme occasions, were reviewed in the available literature. Also, a questionnaire was circulated around Europe for feedback on national legislation, prohibited substances and relevant national tests.

TRL Report TRL570

Texture depth and skid resistance of Gripfibre


Published: Jan 01, 2003 by TRL Report TRL570
Authors: J C Nicholls and M J McHale
Subjects: Engineering - Civil, Materials Science

The skid resistance and texture properties from sites with Gripfibre, a microsurfacing system with polymer modified emulsion and synthetic fibres, were assessed. Skid resistance and texture depth data from road trials were compared to that from adjacent sections with different surfacings.

TRL Report TRL557

Durability of thin asphalt surfacing systems: Part 1 Initial findings


Published: Jan 01, 2002 by TRL Report TRL557
Authors: J C Nicholls, I Carswell and P C Langdale
Subjects: Engineering - Civil, Materials Science

Published information and data currently available from the trial sites with thin surfacing systems, introduced into the UK in 1991, confirmed the suitability of proprietary thin surfacings. The systems were grouped into 5 categories with data on early sites being available from 4 of them.

TRL Report TRL522

A history of the recent thin surfacing revolution in the United Kingdom


Published: Jan 01, 2002 by TRL Report TRL522
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

A review of the major changes that have occurred in the surface course materials used in the UK during the 1990s. Until the mid-1990s, most asphalt surfacing was carried out at nominal thicknesses of 40 mm or greater in hot rolled asphalt or dense bitumen macadam. The types of thin surfacing, and their introduction into the UK, are described.

TRL Report TRL497

The design of porous asphalt mixtures to performance-related criteria


Published: Jan 01, 2001 by TRL Report TRL497
Authors: J C Nicholls and I Carswell
Subjects: Engineering - Civil, Materials Science

Laboratory tests for permeability, particle loss, scuffing and binder/aggregate affinity were used to compare porous asphalt samples from site with laboratory samples. A laboratory design procedure for porous asphalt is proposed to reduce the current high cost of the material when procured under the current specification clause.

TRL Report TRL499

Material performance of porous asphalt, including when laid over concrete


Published: Jan 01, 2001 by TRL Report TRL499
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

The results from trial sites with porous asphalt on the A38 at Burton, the M1 at Wakefield, the M40 in Oxfordshire and the M4 at Cardiff, all carrying heavy traffic, were discussed and conclusions for the use of porous asphalt drawn.

TRL Report TRL496

Protection provided by surface dressings and thin surfacings to structural pavem


Published: Jan 01, 2001 by TRL Report TRL496
Authors: L J Milton, M H Burtwell and J C,Nicholls
Subjects: Engineering - Civil, Materials Science

A literature review and an investigation into existing sites with surface dressing or thin surfacing were made. The findings showed that the treatments have little or no direct strengthening effect on the structural performance of a highway pavement. However, they may have an indirect stiffening effect by virtue of sealing the surface.

TRL Report TRL376

Effectiveness of edge drainage details for use with porous asphalt


Published: Jan 01, 2001 by TRL Report TRL376
Authors: J C Nicholls and I G Carswell
Subjects: Engineering - Civil, Materials Science

Results from in-situ measurements of relative hydraulic conductivity on existing edge details for sections with porous asphalt and a programme of laboratory tests on each of the edge details are reported. The in-situ measures were of the relative hydraulic conductivity across the pavement near edge details after different times in service. The laboratory trials showed that water flows over, as well as through, porous asphalt.

TRL Report TRL435

Information on the properties and performance of Smatex, a proprietary thin surf


Published: Jan 01, 2000 by TRL Report TRL435
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

Information on the properties and performance of Smatex, a proprietary thin surfacing system from Aggregate Industries Limited, was assembled and assessed. The system was found to comply with all stages of the Highways Agency 5-Stage Procedure for Evaluating New Materials for use as a thin surfacing on trunk roads, including motorways, in England.

TRL Report TRL434

Assessment of THINPAVE, a Bardon thin asphalt surface course


Published: Jan 01, 2000 by TRL Report TRL434
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

Information on the properties and performance of Thinpave, a proprietary thin surfacing system from Aggregate Industries Limited, was assembled and assessed. The system was found to comply with all stages of the Highways Agency 5-Stage Procedure for Evaluating New Materials for use as a thin surfacing on trunk roads, including motorways, carrying up tp 1,500 cv/l/d in England.

TRL Report TRL461

The harmonised European standard test methods for asphalt mixtures


Published: Jan 01, 2000 by TRL Report TRL461
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

The proposals for European tests were reviewed with an emphasis on comparison with current British tests and on their suitability for use with performance-related specifications. Tests not currently used in the UK are described and attention drawn to significant differences between draft European methods and their BS equivalents.

TRL Report TRL461

The harmonised European standard test methods for asphalt mixtures


Published: Jan 01, 2000 by TRL Report TRL461
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

The proposals for European tests were reviewed with an emphasis on comparison with current British tests and on their suitability for use with performance-related specifications. Tests not currently used in the UK are described and attention drawn to significant differences between draft European methods and their BS equivalents.

TRL Report TRL292

Assessment of MILLOM HITEX, the Bardon thin asphalt course


Published: Jan 01, 1998 by TRL Report TRL292
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

Information on the properties and performance of Millom Hitex, a proprietary thin surfacing system from Aggregate Industries Limited, was assembled and assessed. The system was found to comply with all stages of the Highways Agency 5-Stage Procedure for Evaluating New Materials for use as a thin surfacing on trunk roads, including motorways, in England.

TRL Report TRL315

Specification trials of high-performance hot rolled asphalt wearing courses


Published: Jan 01, 1998 by TRL Report TRL315
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

A specification clause and associated notes for guidance were prepared for hot rolled asphalt in terms of the wheel-tracking test and air voids content. The clause was trialled and refined on road contracts. Results during construction and subsequent monitoring were analysed to show that the approach is practicable.

TRL Report TRL314

Road trials of Stone Mastic Asphalt and other thin surfacings


Published: Jan 01, 1998 by TRL Report TRL314
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

Road trial sites with surface course materials were monitored for up to six years. Four sites with sections of stone mastic asphalt surface course and one with a multiple surface dressing thin surfacing system complement the previously reported sites with proprietary thin surfacing systems. The overall performances of the materials are encouraging, with several of the proprietary thin surfacings now having Departmental Type Approval for use on trunk roads and motorways in England.

TRL Report TRL125

Trials of high-friction surfaces for highways


Published: Jan 01, 1998 by TRL Report TRL125
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

Road trials, mostly on approaches to roundabouts, compared the performance of 3 alternative resins with those of epoxy-resin in high-friction surfacing systems. The overall ranking order of resins trialled beginning to emerge was epoxy-resin, polyurethane-resin and acrylic-resin just ahead of the rosin-ester system. Laboratory tests gave a similar ranking. A performance-related criterion for a certification procedure was developed.

TRL Report TRL250

Design of long-life flexible pavements for heavy traffic


Published: Jan 01, 1997 by TRL Report TRL250
Authors: M E Nunn, A Brown, D Weston and J C Nicholls
Subjects: Engineering - Civil, Materials Science

Information on the performance of heavily trafficked roads shows that deterioration (cracking or deformation) is usually found in the surfacing rather than deeper in the pavement structure and the majority of thick pavements maintain their strength over time. These roads are referred to as long-life roads.

TRL Report TRL157

Rheological properties of polymer-modified binders for use in rolled asphalt wea


Published: Jan 01, 1997 by TRL Report TRL157
Authors: D R Gershkoff, J Carswell and J C Nicholls
Subjects: Engineering - Civil, Materials Science

Fundamental and empirical tests were performed on 11 binders and bituminous mixtures with the same aggregate grading. The results showed that the empirical binder tests are deficient in predicting the performance of modified binders in mixtures. Dynamic tests are better, but relationships need to be developed. Deformation results from a full-scale road trial using modified binders validated the laboratory tests.

TRL Report 176

Laboratory tests on high friction surfaces for highways


Published: Jan 01, 1997 by TRL Report 176
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

A series of test protocols are proposed which define a laboratory test programme to assess the performance of high-friction surface systems. The programme involves 3 simulative tests, a thermal movement test and 3 conditioning tests together with 3 optional tests.

TRL Report TRL218

Assessment of AXOFLEX, the Redland thin asphalt surface course


Published: Jan 01, 1997 by TRL Report TRL218
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

Information on the properties and performance of Axoflex, a proprietary thin surfacing system from Redland Aggregates Limited, was assembled and assessed. The system was found to comply with all stages of the Highways Agency 5-Stage Procedure for Evaluating New Materials for use as a thin surfacing on trunk roads, including motorways, in England.

TRL Report TRL261

The long-term performance of a surface dressing trial on A413, Amersham


Published: Jan 01, 1997 by TRL Report TRL261
Authors: J C Nicholls and D P Frankland
Subjects: Engineering - Civil, Materials Science

A length of road with sections of differently designed surface dressing was monitored. All dressings performed well with a linear rate of decay of texture during the first two was proportional to the Flakiness Index of the primary aggregate although absolute values of texture could not be confidently predicted from the data types normally available.

TRL Report TRL264

Review of UK porous asphalt trials


Published: Jan 01, 1997 by TRL Report TRL264
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

The experience gained from extensive road trials back to 1967 were reviewed and recommendations are derived to assist those involved in the design, manufacture and application of porous asphalt, particularly with a 20 mm nominal aggregate grading. Aspects of maintenance for porous asphalt that are different from that of traditional, impervious surfacings were discussed.

TRL Report TRL121

Laboratory testing of road-marking materials


Published: Jan 01, 1995 by TRL Report TRL121
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

Laboratory wear tests were carried out to try to replicate the performance achieved in road trials for a set of typical materials. The tests showed that the wear regime could be used to differentiate between materials, but the results do not replicate those obtained on the same materials from the standard road trials. A standardised procedure has been derived.

TRL Project Report PR79

Road trials of thin wearing course materials


Published: Jan 01, 1995 by TRL Project Report PR79
Authors: J C Nicholls, J F Potter, J Carswell and P Langdale
Subjects: Engineering - Civil, Materials Science

The early-life performance of road trials of proprietary thin surfacing techniques (1 site with UL M, 7 sites with Safepave) were summarises. Most of the claims for the materials appear were confirmed, but there were reservations regarding surface texture. Visual surveys showed significant consolidation of material in the wheel-paths whilst SCRIM results were unaffected. Generally good integrity and adhesion of the surfacing was found.

TRL Project Report PR61

Assessment of Multiphalte, the Shell multigrade bitumen


Published: Jan 01, 1994 by TRL Project Report PR61
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

A review of Shell Multiphalte bitumen was undertaken based on laboratory and road trials carried out by Shell and by various independent laboratories together with the TRL road trials of rolled asphalt on the A38 at Burton in 1987. Shell Multiphalte bitumen has properties that may be usefully employed in appropriate circumstances to enhance the deformation resistance of rolled asphalt surfacings.

TRL Project Report PR109

EVATECH H polymer-modified bitumen


Published: Jan 01, 1994 by TRL Project Report PR109
Authors: J C Nicholls
Subjects: Engineering - Civil, Materials Science

The rheological properties of Evatech H, a bituminous binder modified with ethylene/vinyl-acetate co-polymer show that the properties usually desired of binders for use in mixed materials are enhanced when compared to those of conventional binders. This enhancement was confirmed using the wheel-tracking test on samples of a typical rolled asphalt wearing course mixture.

TRL Project Report PR61

Acceptable weather conditions for laying bituminous materials


Published: Jan 01, 1993 by TRL Project Report PR61
Authors: J C Nicholls and M E Daines
Subjects: Engineering - Civil, Materials Science

A methodology for calculating the temperature of asphalt following laying pavement layers with mixtures commonly used in the UK were developed based on cooling criteria. These can either be used directly to provide a consistent set of method-based specification requirements or, with the move towards performance-based specifications, by contractors to assess the probability of complying with performance criteria.