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Dr Arshad (Ash) Ahmed
Lecturer in (Construction) Materials Science
Module Leader, Construction Materials and Structures I & II
Course Tutor, HND Building Studies

a.r.ahmed@leedsbeckett.ac.uk

Dr Arshad Ahmed

I have an extensive research background. As Materials Science is arguably one of the most versatile disciplines encompassing all aspects of Engineering (Mechanical, Civil (Construction), Aerospace, Electrical, Chemical, Telecoms, etc) and Applied Sciences (Physics, Chemistry, Geology, etc), the breadth of my research experience involves the Aerospace, Chemical, Telecoms and Construction sectors. I specialize particularly in evaluating the mechanical and physical properties of all types of commercial materials (I have worked with metals, polymers, ceramics, glasses, and construction materials (blockwork, bricks, mortars, etc). I have also worked as a consultant, evaluating the flexural strength of masonry panels under vertical loads.

I am the module leader for 2 different Materials modules, which helps to give the student an appreciation for the various types of materials used in Construction / Civil Engineering and their mechanical and physical properties.

Academic Background

BSc (Hons) Materials Science, Manchester Materials Science Centre, UMIST / University of Manchester
DELE - Diploma en la lengua Espanola, University of Salamanca, Spain

Research Degrees

MPhil - Metallurgy
Manchester Materials Science Centre, UMIST / University of Manchester
Project Title: Residual Stresses of the Bond Coat and Ceramic Top Coat in a Thermal Barrier Coating During Thermal Cycling
Sponsors: Volvo Aero Corporation

Synopsis:
It has been widely suggested that the lifetime of Thermal Barrier Coatings (TBCs) is limited by oxidation of the metallic bond coat material. However, recent studies have shown that creep of the bond coat may also be a significant factor in the lifetime of TBCs. The primary objective of this work was to measure the stress in the NiCoCrAlY bond coat and ZrO2 ceramic top coat of a TBC by monitoring the amount of bending of the substrate to which it was attached during thermal cycling up to 700 °C. Mechanical (Young's modulus, hardness, tensile properties) and physical (microstructure and CTE - coefficient of thermal expansion) properties of the bond coat and substrate material were measured to obtain a better understanding of the system. These results were put into an elastic model for the system, and this was then correlated with the stress measurements. There was good agreement between the model's predictions and the measured values. The main conclusion of the study was that the bond coat deforms mainly elastically during thermal cycling up to 700 °C. Further measurements revealed similar behaviour for the ceramic top coat.

PhD - Polymer Science
Heriot - Watt University, Edinburgh
Project Title: Polymer Gel Electrolytes for Utilisation in SMART Windows
Sponsors: Pilkington Glass, EPSRC

Synopsis:
Polymer gel electrolytes have many favourable features that can be used in Smart Window application where they are the conducting layer in an electrochromic device. Amylose polymer electrolytes were investigated comprising various solvents (N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP) and N,N-dimethylformamide (DMF)) incorporating lithium based salts (lithium chloride or lithium triflouromethanesulphonate). These solutions had very high ionic conductivity in the range 10-3 - 10-2 S/cm and very low temperature dependence on conductivity (as low as 5 - 10 kJ/mol-1). The solutions were successfully thermally cross-linked allowing in-situ cross-linking for Smart Windows. Cross-linking did not significantly reduce the ionic conductivity.

The amylose gel electrolytes were successfully tested on Smart Windows. Instantaneous colouring responses were obtained at > 1V in electrochromic cells (Smart Windows) requiring no pre-conditioning of the cell. Colouring response was very quick (8 - 15 seconds at 3V and 20 - 35 seconds at 2V at room temperature) and response times (colouring and bleaching) did not vary significantly (as low as 10% difference) at 70 C and -15 C. The use of coloured windows reduces transmission by up to 70%.

Work Experience

Rolls - Royce
Dept: Metallurgical Laboratory
Role: Conducting research on titanium fan blades used in aero engines

Terahertz Photonics
Dept: Materials Research and Development
Role: Developing polymers for utilisation in the telecoms sector

Kingston University
Dept: Faculty of Engineering
Role: Post-Doctoral researcher
Project title: Low Density Aircrete for Utilisation in Dwellings in the UK
Sponsors / collaborators:
EPSRC, Kingston University and Industry (Building Research Establishment (BRE), Celcon, Corus-Catnic UK, National Housing Building Corporation (NHBC), Quinn-Group, Tarmac Topblock, Thermalite and The Office of The Deputy Prime Minister (ODPM).

Synopsis:
The objective of the project is to pick up on the need to adjust UK design procedures to reflect developments in the structural Eurocode 6 and the supporting CEN TC 125 standards. There is a particular opportunity to improve productivity by using low density aircrete (autoclaved aerated concrete) masonry walls. Low density aircrete blocks improve the efficiency of construction as they are easily manhandled and readily cut, shaped and chased. The fact that these units have a very low density (typically 350kg/m3) and have a high air content, they provide a high level of thermal insulation. This assists in meeting the proposed changes to Part L of the Building Regulations, thereby addressing the key environmental need to reduce the consumption of carbon based energy.

Based on the results obtained, practical issues for using low density aircrete were given. These cover (i) Chasing and cutting, (ii) Finishes - plaster/render/dry lining. Bond testing will be carried out if necessary, (iii) Weather protection systems and (iv) The use of bed joint reinforcement to control movement. The programme of work was divided into three categories: physical properties (moisture, freeze, thermal and sound), mechanical properties (flexural, shear and compressive strengths) and structural performance (where blocks support lintel bearings, joist hangers and pull out tests for wall ties and fixngs) of low density aircrete. The properties of both conventional and thin layer mortar were investigated.

Publications

Ahmed, A., Fried, A.N., Limbachiya, M., Roberts, J.J., IBMaC 2004, Advantages and Implications of High Performance Low Density Aircrete For the UK Construction Industry, 13th International Brick / Block Masonry Conference, Amsterdam, Holland, 4 - 7 July.

Ahmed, A., Fried, A.N., Limbachiya, M., Roberts, J.J., Implications of Using Thin Layer Mortar with Blockwork, Masonry International, August 2005.

Ahmed, A., Fried, A.N., Limbachiya, M., Roberts, J.J., Summary of the Flexural Strength of Low Density Aircrete Walls, Proceedings of the 4th International Autoclaved Aerated Concrete Conference: Innovation and Development, London, September 8 - 9, 2005.

Ahmed, A., Fried, A.N., Limbachiya, M., Roberts, J.J., Properties of Conventional and Thin Layer Mortar, Proceedings of the 4th International Autoclaved Aerated Concrete Conference: Innovation and Development, London, September 8 - 9, 2005.

Ahmed, A., Fried, A.N., Limbachiya, M., Roberts, J.J., Moisture Properties of Low Density Aircrete, to be presented at the 4th International Autoclaved Aerated Concrete Conference: Innovation and Development, London, September 8 - 9, 2005.

In press (May 2006)

Ahmed, A., Cowie, J.M.G., Arrighi, V., Physical Properties of Amylose Polymer Electrolyte Solutions and the Effects of Cross - Linking.

Ahmed, A., Cowie, J.M.G., Arrighi, V., Performance of Amylose Electrolytes in Smart Window Applications

Ahmed, A., Cowie, J.M.G., Arrighi, V., Comparison between Amylose and Cellulose Polymer Electrolytes for Smart Window Applications

Ahmed, A., Fried, A.N., Limbachiya, M., Roberts, J.J., Load - Bearing Properties of Low Density Aircrete Blockwork, British Masonry Society Conference, London, October, 2006.

Ahmed, A., Fried, A.N., Limbachiya, M., Roberts, J.J., Load - Bearing Properties of Low Density Aircrete Blockwork, British Masonry Society Conference, London, October, 2006.