A dissertation submitted to the Faculty of Science University of the Witwatersrand, Johannesburg for the degree of Master of Science / The object of this dissertation is to develop a cost effective plasticiser/water-reducer from tannin extracts which does not retard initial strength development. Model compounds of tannins indicated the suitability of substiuued phenols for this purpose, Catechol with adjacent hydroxide groups gave a good combination of improved workability with compressive strengths equivalent to the control. Combinations with ammonia and torrnaldehyde resulted in some greatly improved performances, but also reduced stability of the additives. Urea and metabisulphite did provide some improvements ai!1ddid not adversely affect shelf life. Some of the tannin extracts tested on their own gave considerate improvements in workability and some strengths. To improve the stability of extract solutions, tannins were modified with urea, metabisulphite, small amounts of potassium hydroxide and a alcohol mixture used for pretreatment. Only the first two listed were consistently effective without producing any disadvantages. They even further improved the concrete performance of condensed tannins in particular. Small additions of TEA or its acetate salt resulted to better one day strengths of the modified tannins. Analytical techniques such as infrared and nuclear magnetic resonance were used to monitor some; modifications of the tannins and their result. A test representing early hydration conditions and X-ray diffraction provided clues to the additives mechanism in its interaction with cement. The additives performance was evaluated by comparison with a leading plasticiser/water-reducer, an independent concrete testing laboratory and conduction calorimetry by a research and testing council. A tannin based plasticiser made largely from local raw materials was quickly accepted during a recession by brick and precast manufactures . / Andrew Chakane 2018

A new peat replacement product is being manufactured in South Africa. This product which is marketed under the brand name Fibregro is made from spent wattle bark originating from the tanning extract manufacturing process. Fibregro is currently being used in South Africa to dilute and in some instances replace local peat in mushroom and horticultural applications. In addition to its role as a peat replacement, Fibregro is in a position where it could also qualify to cany a Forest Stewardship Council (FSC) label. Once in full production it is estimated that the company will be able to produce more products than can be sold locally. As a result export opportunities need to be pursued. The United Kingdom (UK) was identified as a potential export destination on account of developments in this country in respect of the certification of forest products (especially FSC certification) and moves to reduce peat mining. A mail survey was undertaken amongst growing media producers in the UK to address two key issues relating to Fibregro, namely: • Whether Fibregro's peat free status could be exploited in the UK growing media and mushroom casing markets. • Whether enough advantages existed in the UK market to justify the extra effort and cost associated with qualifying Fibrego to carry an FSC label. Key findings arising from this survey indicate that a niche is developing in the UK growing media market for a good peat substitute. The addition of an FSC label will render the product unique in the growing media market in this country. A number of recommendations arise from this work. These are: • In order to penetrate the UK growing media market Fibrgro must be positioned as an effective peat reducing agent which is capable of extending the peat reduction levels beyond that of composts. • Fibregro distributors should be identified from amongst the larger growing media producers in the UK. • Potential use of Fibregro as a mushroom casing in the UK appears to be limited. • A combination of peat free and FSC labelling while capable of rendering Fibregro unique in the UK growing media market needs to be carefully considered on account of chain-of-custody requirements along the supply chain. / Thesis (M.B.A.) University of KwaZulu-Natal, Pietermaritzburg 2004.