Civil Engineering/Expansion joints


Dear Khan

Iam executing a huge underground tank (sewage tank) are dimensions 72*60.5*6m and the thick of foundation is 1m and wall width 600mm all around foundation and the tanks divided to three partitions by two walls in mid of tank also width of these walls 600mm

My query is that sewage tank need for expansion joint and if neccessary need I afraid from the groundwatr leaking to do expansion joint with gap because of water level of this area 1.5m.
Pls could u advise ASAP.

My best regards.

Hi Mohammed,

As the tank is underground, I would recommend that you do not have any expansion joints as after construction the temperature differences will be minimal. During construction, however, you will need to en careful about early age cracking due to shrinkage, etc, so I would recommend that you detail some construction joints every 10-12m, with shrinkage gaps of between 1 to 1.2m, which would be cast say after 1-2 weeks after the walls either side have been cast.

The same precautions should be adopted for the roof slab.

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Arshad Khan


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.


Employment history: 40 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.

.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)

•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 •2013: IEK International Conference, Kisumu, Kenya

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 2010)

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