Large amounts of fly ash (FA) and limestone powder (LP) wastes are accumulating in countries all over the world. Most of these wastes are abandoned and cause certain serious environmental problems and health hazards. In this study. LP waste and class-C FA were used to produce a composite material without the addition of portland cement. LP was mixed with the FA at levels of 10, 20 and 30% by volume in the samples. LP and FA were mixed, wetted and compressed under high pressure in a steel mould. The compressive and flexural strengths were measured, and ultrasonic pulse velocity tests were performed on samples at ages of 7, 28 and 90 days. Density, water absorption and thermal conductivity values were also determined for the samples aged for 28 days. Preliminary results obtained from the tests indicate that masonry composites can be produced using LP. FA and water. (C) 2010 Elsevier B.V. All rights reserved.