Cob: Lime over cob/adobe/-resource articles

[Matthew HALL(SED)]

Charmaine
We use naturally hydraulic lime (NHL) over here in the UK quite often and it is easy for us to get
hold of. The local lime quarry makes a variety of slaked lime products, have a look at their
website if you are interested:

Bleaklow slaked lime products
www.bleaklow.co.uk

Naturally hydraulic lime (NHL) is available here in three types: NHL 2, NHL 3.5, and NHL 5. The
number relates to the compressive strength you can acheive. % being a strong mix, 2 being a weak
one. These are rarely used however as NHL 3.5 is very commonly used. It is about £10 per bag (25Kg
dry) as opposed to OPC which os about £3-50. You have the advantage of course that it will set in
damp conditions and adequate strenght can be gained same as for cement so construction is quicker.
I saw a building being made over here with a natural stone wall and non-hydraulic lime putty used
for the mortar. The wal had been up for 2 months and then was washed to the ground in a rain
storm!! The stone mason was not impressed...Should have used NHL.
Regards
Matthew

____________________________________________________________________
Matthew Hall BSc (Hons) GradBEng
Centre for the Built Environment
Unit 9 Science Park
Sheffield Hallam University
Pond Street
Sheffield S1 1WB
England

Tel: +44 (0) 114 225 3200
Fax: +44 (0) 114 225 3206
E-mail: M.Hall at shu.ac.uk
Webpage: http://www.shu.ac.uk/schools/sed/earth