Southampton Solent
University
Southampton Solent University with
the Good Earth Trust promotes
projects in Africa that utilise
interlocking rammed earth blocks
Commercial
brick kilns
Oil fired /
coffee
husks?
Quarried stone blocks.
Transport?
Deforestation
Release of
CO2
Manual
production
of ISCEB?
The interlocks
between the
earth blocks
reduces the
need for
10+mm mortar
joints as can be
seen here with
fired bricks
Hand made unstabilised blocks
in Eastern Chad
HAT & BOOTS!
1year of weathering in exposed
UK location
LIME
PLAIN
CEMENT
6 years of weathering in UK
Rammed
Lime Plain Cement
Lime and cement stabilisers are
normally used, but research into the
use of enzymes and polymers is
being conducted to provide
innovative low carbon alternatives to
cement. Also, there is significant
research into the production of low
carbon cements
Lime stabilisation:
Calcium carbonate in various
types of limestone are burnt and
slaked to produce hydrated,
hydraulic or natural-hydraulic
limes (NHL). Normally, NHL is
mixed with the soil to produce
stabilised blocks.
Low carbon cements:
In a drive to reduce the
environmental impact of cement,
different low carbon alternatives
are being developed. These will
have a dramatic effect on the
amount of CO2 used in
stabilising ISSB earth blocks.
Enzymes:
These are bio-molecules or proteins
that will create a catalytic chemical
reaction in soils to produce blocks
of similar strength and durability to
cement or lime stabilised blocks.
Polymers:
Geopolymers are based on lumino
silicates that create a chemical
process to turn them into a binder
that does not release CO2, and takes
place at temperatures lower than that
needed for cement production. 300
kg of CO2 per tonne is emitted,
compared with 700+ kg for OPC.
Two materials are used to create a
geo-polymeric cross-linking of
clay soils. Sodium hydroxide,
NaOH (caustic soda) is mixed with
lime and a reaction takes place at
low temperatures in excess of
25°c to stabilise blocks
Surface treatments:
Not only can the durability of a block
be improved by stabilisation, the
application of various coatings will
also improve them. 4:1 old engine
oil/diesel mix proves very effective
Engine oil and unfinished after
erosion.
Plain
Lime
Cement
Conclusions:
There is a need for a dedicated
research project into different low
carbon alternatives to stabilising
Interlocking Stabilised
Compressed Earth Blocks
‘my dad says this stabilised earth block
wall has been here for 14 years’
Further details from
gordon.browne@solent.ac.uk