It was with interest and a wry smile that I read David Hayward's article on the problems of using lean concrete on a road base (NCE 17 September).
Almost 20 years ago the problem of cracking of the lean mix concrete road base was manifesting itself in housing estate roads in Kent and East Sussex. At the time I was working for a national house building company and was responsible for all its infrastructure works.
It seemed to me, and also to the local authority engineers who inspected these works, that the problem related to two elements of the construction process: the lack of any controlled movement joints within the lean mix concrete road base and the seasonal movement of the formation in the highly shrinkable London and Gault Clays found in these areas.
The random cracking of the base course and wearing course layers above the lean mix concrete caused so many problems at road adoption stage that I banned its use on all the estate road construction undertaken by the company and the problems did not reappear.
The worst example I encountered was of a recently built and unused estate road in East Sussex which exhibited extensive random cracking of the base course macadam. This particular road was built by the local authority prior to the disposal of the land and so its engineers were aware of the problem from day one.
The presence of cracking in an unused road lends support to the hypothesis that the cracking was caused solely by the materials and not by the use of the road.
FC Parr (M), Eccle Riggs, Holdiford Road, Tixall, Stafford ST18 0XP.
Your article 'Keeping damage under wraps' (NCE 20/27 August) gave an interesting and valuable insight into this emerging application for plastic composites in construction.
Just to keep the record straight it might be worth pointing out to your readers that the bullet-stopping capability of Kevlar, despite the dismissive remark from one of your correspondents, is in fact highly relevant to protection against bridge bashing. Kevlar is inherently less brittle than either carbon or glass making it more resistant to impacts, especially repeated impacts, than either carbon or glass. This basic characteristic remains whether the force applied comes from a bullet or an HGV and accounts for Kevlar's widespread use in boat hulls and other structures prone to collision damage.
Anthony Marchant (F), managing director, CETEC Consultancy, Coopers House, The Horsefair, Romsey, Hampshire SO51 8JZ.
On course for SARTOR
The impression given in 'Surrendering to SARTOR' (NCE 17 September) that Oxford Brookes University will be abandoning a BEng degree in civil engineering is not correct. The points score of our BEng intake is now about 16 and in future we intend to ramp up the entry points to match Standards and routes to registration guidelines.
We offer students an excellent experience from dedicated staff in well equipped facilities. We are very pleased that the quality of the student experience was recognised in our recent TQA visit when civil engineering was awarded 21 out of 24.
Through the Oxford Brookes modular system we can offer students flexible learning in a wide range of subjects. We are always interested in developing new courses to meet industry's and student's needs. Consequently we are considering offering a construction engineering degree in addition to our BEng in civil engineering.
Dr Ian Davey-Wilson, civil engineering admissions tutor, Oxford Brookes University, email@example.com