Construction Products from Waste Fibre Resources: Cement Bonded Sludge Board

摘要

The Building Research Establishment, UK. Is engaged on an extensive programme of research aimed to develop innovative construction products utilising paper mill waste. A series of products, including renders, blocks and clays, and panel products, have been developed. This paper sets out the development of cement bonded sludge boards by using deinking paper sludge. Deinking paper sludge was found suitable for the manufacture of cement bonded sludge board. The composition of paper sludge was analysed, containing about 40% cellulose fibre and 50% ash. The fibres are short and fine with average length being about 0.4 mm. The compatibility study of sludge -cement mixtures showed tha t the whole hydration process of sludge-cement mixture consisted of four stages. The sludge had a better compatibility with cement compared to virgin wood fibre used due to the loss of hemicelluloses or other extractives during pulping process. Hydration temperature consistently decreased with sludge content increased. Compatibility index, thermal index [I(T, t)], has been developed to assess optimum hydration parameters. Optimum hydration required a water:cement ratio of 0.3 for 5%sludge -95%cement mixtures , 0.4 for 15% sludge-85% cement mixtures and 0.4- 0.5 for 25% sludge-75% cement mixtures. The performance test of the cement bonded sludge boards made indicated that the properties of the sludge boards were closely related to the sludge contents. Qualified cement sludge boards can be made with 30% sludge which is equal to the percentage of wood chips for the production of cement bonded particleboard.