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 un-stabilised 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 arenormally used, but research into theuse of enzymes and polymers isbeing conducted to provideinnovative low carbon alternatives tocement. Also, there is significantresearch into the production of lowcarbon cements

Lime stabilisation:Calcium carbonate in varioustypes of limestone are burnt andslaked 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 theenvironmental impact of cement, different low carbon alternativesare being developed. These willhave a dramatic effect on the

amount of CO2 used instabilising 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 blockbe improved by stabilisation, theapplication of various coatings willalso improve them. 4:1 old engineoil/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