Investigation on Alternative Cement Materials in East Africa and Their Sustainable Supply Methodology

在Jomo Kenyatta农业和技术大学的Walter教授、O.Oyawa教授和Kiptanui J.A.Too博士的帮助下，对替代水泥材料及其在民用基础设施建设中的应用进行了调查，重点放在东非的肯尼亚。研究结果表明：在替代水泥材料方面，发现了大量的火山灰替代普通水泥的可能性。然后，将火山灰水泥与当地土壤混合制成稳定土砌块，并对其进行当地住房建设评估。即使低掺量的水泥中掺入7%左右的火山灰，SSB的强度也可以有足够的抗压强度，足以满足低层住宅建设的需要。特别是，发现初始强度略低，然后强度随着时间的延长而增加。研究还发现，日本传统的塑料袋和袋子里填充的当地土壤作为劳力型施工技术，足以在农村地区铺设道路基础，可以可持续地维护当地的公路网，以便将农产品运往城市地区的市场。然而，目前的道路条件不太好，不适合将重型水泥材料运输到城市附近的某个地方进行加工，因此建议工厂建在靠近火山灰矿场的地方。即使拟议的技术适合发展中国家，但这不可能是一项生意；即基于低成本、以劳动力为基础的建筑和当地材料，因此应该采用基层技术转移的方法来发展东非国家的农村地区。

The investigation on alternative cement materials and their application to civil infrastructure construction was carried out by focusing Kenya in East Africa, with helpful assistance from Prof Walter, O. Oyawa and Dr. Kiptanui J.A. Too of Jomo Kenyatta University of Agriculture and Technology. The following conclusions are obtained.As for the alternative cement materials, the large amount of pozzolana which may have high possibility to replace the ordinary cement were found. Then, the stabilized soil blocks made of mixing the pozzolanic cement and local soils were made and assessed for local housing construction. Even though the low amount of cement mixed with pozzolana, about 7%, the strength of SSB can have enough compressive strength which was enough for low rise housing construction. Particularly it was found that the initial strength was a little low; then, the strength increased with time. It was also found that the Japanese traditional "Donou" made of plastic bags and local soils filled in the bag are good enough to made road foundation in rural area as labor-based construction technology, which can sustainably maintain the local road network in order to transport agricultural products to the market in urban area. However, the current road condition is not so good to transport the heavy cementious materials to be process somewhere near urban area, so that it was recommended the factory should be located close to the mining place of pozzolana.Even though the proposed technology is suitable for developing countries, this cannot be a business; that is, based on low cost, labor-based construction and local material, so that grass roots technology transfer methodology should be employed for developing the rural area of East African countries.