Alternatives to Portland cement
Practical Action
Gypsum plaster is not wholly resistant to moist conditions and so is normally used internally,
except in the drier Mediterranean and Middle Eastern countries where it has traditionally
been used as an external render.
Other alternative binders
Sulphur is used as an alternative binder in the Gulf region, where a million tonnes a year
comes from natural gas plants in the United Arab Emirates. In some other locations, such as
St Lucia, sulphur that accumulates around the vents of volcanic fumaroles is utilized.
A mixture of 15–25% molten sulphur, heated to around 130°C with 5% of organic additive,
and 75–85% sand or other mineral aggregates which have previously been heated to 160–
170°C, can be cast and de-moulded in only about five minutes. The additive is mainly used
to impart durability. Sulphur concrete has applications which either exploit its quick curing
and corrosion resistance or in situations where Portland cement concrete is expensive,
unavailable or, for example in freezing conditions, impracticable.
Earth mixed with water to form mud has been, and continues to be, used over much of the
world as a binding material. It develops quite a strong adhesion to fired clay brick and sun
dried mud brick masonry and is satisfactory provided the mud mortar is protected from
rainwater. A useful practice is to use mud mortar in the internal parts of the wall and do the
external pointing in a cement or lime-based mortar. The best soils for building purposes
contain both sands and clays and therefore it may be necessary to mix two different soils to
obtain good results. Mud mortars have, traditionally, been improved by the addition of organic
matter such as straw and cow dung.
A number of other alternative binders have been used in a number of applications, which
generally relate to soil stabilisation, waterproofing, or the application of a waterproofing or
wear resistant coating to vulnerable earth based constructions. Such binders include tars and
bitumens (as by-products from petro-chemical industries), sodium silicate (produced from the
heat activated reaction between silica and sodium hydroxide), casein (milk whey), oils and
fats, molasses, and certain locally specific plant-based materials such as gum arabic, other
specific resins and the sap, latexes and juices from specific trees and other plants.
References and further reading
Hydraulic Lime - An Introduction Practical Action Technical Brief
Methods for testing lime in the field Practical Action Technical Brief
How to calculate the Energy Efficiency of Lime Burning Practical Action Technical
Brief
How to Build a Small Vertical Shaft Lime Kiln Practical Action Technical Brief
Lime Kiln Designs Small & Medium Scale Oil Fired Lime Kilns Practical Action
Technical Brief
A Small Lime Kiln for Batch and Continuous Firing Practical Action Technical Brief
Pozzolanas: Lime-pozzolana Cements Practical Action Technical Brief
Pozzolanas - An Introduction Practical Action Technical Brief
Testing methods for pozzolanas Practical Action Technical Brief
Pozzolanas: Portland-pozzolana Blended Cements Practical Action Technical Brief
Pozzolanas - Calcined Clays & Shales, and Volcanic Ash Practical Action Technical
Brief
Pozzolanas - Rice Husk Ash and Pulverised Fuel Ash Practical Action Technical Brief
Clay as a Binder: Introduction Practical Action Technical Brief
Small Scale Production of Lime for Building John Spiropoulos, GTZ,1985
Gypsum Plaster: Its Manufacture and Use, A. Coburn, E. Dudley and R.Spence,
Practical Action Publishing, 1989 ISBN: 9781853390388
Appropriate Building Materials, Roland Stulz and Kiran Mukerji, co-published by
Practical Action Publishing – UK, SKAT ISBN: 9781853392252
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