ABSTRACT
The principles of sustainable development require the minimisation of the production of waste, the efficient use of materials and the recycling of wastes. The UK government is committed to pursuing opportunities for the promotion of reuse and recycling of waste materials where they can substitute for primary minerals. The Minerals Planning Guidance Note (MPG6) published in 1994 proposed that an increasing contribution to aggregate needs should come from alternative sources, which include secondary materials, industrial by-products and wastes. This paper addresses the development of innovative, sustainable materials which provide an alternative to using primary materials in footpath construction.
Canal towpaths are a unique part of our heritage and the single most important means of enjoying the countryside next to the canals national network. Surveys show that people value canal towpaths as a resource to be cherished. Having a well cared for and publicised canal footpath network improves the quality of our lives. Unfortunately the traditional use of black ash in towpath construction does not provide a durable solution contributing to problems i.e. they are often found to be muddy, boggy, flooded, covered by vegetation and can have dangerous potholes.
The paper addresses the use of secondary binders and aggregates in developing hydraulically stabilised materials as an alternative solution to overcome those problems outlined above. These materials offer long term workability, ease of production, handling and laying and most importantly long term performance, thus minimising future maintenance costs. This new solution has been delivered through a partnership involving British Waterways and Tarmac established in 2000 to produce “the” ideal towpath/footpath wearing course material. To address the aesthetic requirements of colour, texture and also short and long term compressive strengths, a material was developed based on the principle of slag bound mixtures (SBM) which utilises granulated blastfurnace slag as the binder.
This paper presents a brief history of canal towpaths in UK and gives an overview of the materials and construction practices used. It describes both the initial trials and some recent contracts undertaken for British Waterways using SBM and outlines the advantages that can be gained by using this material.
