Civil Engineering/core test result

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Expert: - 7/28/2011


Question
Dear Sir,
Good Day!
While done a core test for the roof  on a 9 yrs old existing building(ground only),the compressive strength of concrete fcu, I received from soil lab is  48 N/mm2.But the real fcu while casted was 35N/mm2 .Is it possible to get a higher value after a period of 9 yrs.Is it a fake report? thanx so much.

Answer
Hi Ravi,

Firstly you should always take 3 core samples from each location to cater for coring/testing variances, and use the average for assessment. As for increase in strength, yes you can get quite substantial increase in strength with age (see graphs in concrete books, such as Reynolds) and you have to remember that most concrete mix designs require a margin on top of the specified fcu, so it is quite possible that the actual fcu as cast may have been closer to 40 N/mm2 anyway.

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Arshad Khan

Expertise

I can answer any questions to do with civil and structural engineering consultancy and construction industry in East Africa and the Middle East, and specifically with the analysis and design of reinforced concrete structures. My particular expertise is in the aseismic design and optimisation of tall buildings.

Experience

Employment history: 36 years in Construction and consultancy in the UK, Kenya, Tanzania, Uganda, Ethiopia, Eritrea, South Africa, Somalia, Zambia, Austria, Bahrain, Kuwait, Doha and the U.A.E.

Organizations
.Fellow of Institution of Structural Engineers (UK) .Fellow of Institution of Civil Engineers(UK) .Member of the Institution of Engineers, Kenya .Registered Engineer, ERB, Kenya .Member of the Architectural Association of Kenya (Engineers Chapter) .Chartered Engineer (UK)

Publications
•1984: International Conference on the Art and Practice of Structural Design, London •1994: 3rd Int. Kerensky Conference in Structural Engineering, Singapore •2008: International Conference on High-Rise Towers, Abu Dhabi

Education/Credentials
BSc, 1st Class Hons, in Building Engineering, University of Bath, UK MSc in Concrete Structures and Technology, University of London. Diploma of Imperial College, UK.

Awards and Honors
•Science Congress Special Award (for 2-seater Hovercraft - 1968) •Institution of Civil Engineers Award for outstanding performance at Bath University (1975) •Concrete Society Postgraduate study Bursary Award (1976) •Consular Representative for British High Commission, Nairobi. (1995 to 1998) •Examiner for Institution of Civil Engineers Professional Interviews, Nairobi. (1997 to 1998) •Branch Representative in Vienna for PI assessment for Inst. of Struct. Engrs. (1999 to date)

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