Ghana needs a paradigm shift from the monopoly of cement as the binding agent in the construction industry. As we all know, housing is one of the requirements of man; the ambition of all people to own or have access to decent shelter is not a luxury but a necessity. Different materials are used around the globe for housing, especially for walling.

Freestanding walls and building structures with load-bearing and non-load bearing walls are common in Africa including Ghana because they are simple to construct and easily affordable. How affordable is our so-called affordable houses in Ghana? We grew up with the word cement as a binding material in building construction. Cement is a basic building material that will continue to be in demand far into the future. A world without cement is hard to imagine.

Cement is a vital construction material and also a strategic commodity. The world currently produces nearly 3.6 billion metric tonnes of cement each year, with volume predicted to rise to more than 5 billion metric tonnes by 2030. In Ghana, the major problem with regard to the Ghana cement industry is the dependence of cement manufacturers on the market import of clinker and gypsum which are the main ingredients for cement production. In other words, these manufacturing companies and other brands in the market do not produce clinker and gypsum in Ghana on their own.

Government currently spends, at least, $350 million every year to import about 85 per cent of cement materials. Pozzolana or pozzomix cement is the saviour if attention is given to it. Research and development activities by the local institution (BRRI-CSIR) have proven that pozzolana can replace up to 40 per cent of cement for concrete works and general construction. From the ecological perspective, pozzolanic materials contribute little effects to environmental hazards as compared with cement production in terms of CO₂ emissions and promote climate change with greenhouse effects.

The Kyoto Protocol which came into being in 1997 highlights the principles of Clean Development Mechanism (CDM) (UNEP Collaborating Centre on Energy and Environment). CDM allows emission reduction in developing countries like Ghana. In contributing to the global net effects of CO₂ emission, then the need to use more pozzolanic materials like pozzomix cement in Ghana and less of cement to achieve this aim.

Since pozzomix cement refines pore structure of cement by making it denser, it will mean that there will be a reduction of chemical attacks, early shrinkage and minimize the leaching action of cement compounds. Some of the properties worked on were compressive strength, fineness, soundness, setting time, and specific gravity, loss on ignition, and insoluble residue as physical properties of cement and chloride content.  

Pozzolana cement improves strength, workability, durability very effective in green building construction. In a research, substitution with locally available material (pozzomix cement) up to 30% to 40% will greatly reduce cost of cement production up to 20% with clinker importation by 15 % to save Ghana US$30million annually. Studies on the pozzolanic activity of some clay samples in Ghana for housing construction carried out recently showed that in 28 days, the compressive strength of pozzolana cement mortar up to 30% satisfied the grade 32.5R cement for concrete works and general construction.

Pozzolana usage reduced heat of hydration damage and increased strength. Natural pozzolanas reduce heat of hydration anywhere from 10-40% during the first 100 hours, depending on the ultimate mix design, therefore lowering the threat of thermal cracking and allowing for a cooler controlled set.

After 100 hours the cement-water hydration process wanes while the pozzolana mixes continue to hydrate until one of the two remaining hydration agents. Calcium hydroxide or natural pozzolana has been consumed. This slows down pozzolanic hydration process for months and even for years, bringing the long term strength of natural pozzolana based concrete well beyond that of ordinary Portland cement (OPC) concretes.

Pozzolana usage inoculate concrete or mortar against chemical attacks. When the chlorides (CH) migrate out of the concretes’ interior capillary action, it leaves behind a maze of porosity that both weakens the concrete and allows for the future ingress of water. This infiltrating water can contain sulphates, chlorides and other damaging chemicals.

In cold climates, the invasive water will freeze, causing freeze-thaw damage to the concrete. Natural pozzolana are so effective in consuming the problem-causing CH to boast concrete high sulphate resistant. Natural pozzolana contributes to a concrete matrix so densely packed that liquid and gas cannot penetrate to cause the steel to corrode.

Furthermore, as concrete hardens, natural pozzolana readily react with calcium hydroxide as it becomes available, trapping any present alkali inside the densified cement paste, which alleviates capillary action and virtually eliminates Alkali-Silica Reaction (ASR) and efflorescence. Natural pozzolana will mitigate and eliminate unsightly efflorescence.

Pozzolana are free of crystalline silica and other hazardous materials as confirmed by research scientists from BRRI-CSIR. Cement is saddled with occasional variability in their chemical and physical properties, a carefully mined and refined natural pozzomix cement is environmentally safe and consistent choice with no health issues while enhancing its performance and durability and significantly increasing both high early and long-term strength workability in mortar and concrete.

The list of benefits from pozzomix cement can continue with its advantage to Ghanaians especially in the rural areas. Government policy is needed to revamp the pozzolana factory in the country.