38 Uganda Journal of Agricultural Sciences, Vol. 12 No.1 June 2006 Production of composite bricks from sawdust using Portland cement as a binder A.Zziwa 1 , S. Kizito 1 , A. Y. Banana 1 , J. R. S. Kaboggoza 1 , R. K. Kambugu 1 and O. E. Sseremba 1 1 Department of Forest Products Engineering, Makerere University, P.O. Box 7062 Kampala, Uganda zziwa@forest.mak.ac.ug Keywords: Sawdust, sawmilling, compressive strength, density, composites, cement Abstract A study was conducted between October 2004 and April 2005 in Kampala District, with the objective of investigating the feasibility of making sawdust-cement composites using saw dust. A total of 48 bricks were made in the Faculty of Forestry and Nature Conservation laboratory based on volume ratios of sawdust to cement (3:2 and 2:1). Mass was measured using a weighing balance and density calculated from mass and volume of the bricks. The composites were tested for compressive strength using a universal testing machine, as they cracked due to compression. The mean compressive strength values were 1.61 N mm -2 and 1.986 N mm -2 for 50 x 50 x 50 mm composites with sawdust to cement ratios of 3:2 and 2:1 respectively; and 1.778 N mm -2 and 2.21N mm -2 for 100x100x100mm composites with sawdust to cement ratios of 3:2 and 2:1 respectively. Analysis of variance (ANOVA) indicated significant differences (P<0.05) in strength values of the two compositions. Soaked composites swelled irrespective of the cement to sawdust ratio. The compressive strength for the soaked bricks was approximately 40% of the dry weight strength. The composite bricks were found to be unfit for paving and medium heavy load wall construction. Due to their light weight, by imparting decorative mosaics they can be used for interior wall paneling and decoration, where minimal wetting is experienced. Introduction The wood utilisation industry in Uganda is characterised by poor harvesting and processing methods, limited value addition and high wastage (Kambugu, et al, 2005). There are currently 130 sawmills operating in Uganda with installed capacities of about 3,000 m 3 of logs per year (Forest Department, 2002). Most of them are the small mobile circular or band saw type with an average recovery of 45% (Jacovelli and Carvalho, 1999). Thus over 50% of the round wood processed is wasted as sawdust, slabs and off cuts. These wastes seldom have commercial use. Sawdust is one of the major underutilized by- products from sawmilling operations in Uganda (Plate 1). The wood loss in Uganda in the form of sawdust is estimated to be 18-20 % of the log volume (Ministry of Water Lands, and Environment, 2002). According to some timber dealers in Kampala suburbs, by December 2005, one cubic meter of Pine timber cost about Uganda shillings 430,000. This implies that on average about Uganda shillings 77,400 was lost per cubic meter in the form of saw dust. The underlying reasons for the inefficiency and waste in the saw milling industry included the Uganda Journal of Agricultural Sciences, 2006, 12(1) 38-44 ISSN 1026-0919 Printed in Uganda. All rights reserved ©2006 National Agricultural Research Organisation