Concrete interlocking paving blocks (CIPB) are widely used in flooring and covering applications such as city roads, pedestrian foots, gardening architecture and many surface coverings. The focus of this study is to evaluate destruction specific energy (SEdes) of CIPB containing fly ash and blast-furnace slag at different curing conditions. The SEdes is estimated from the area (integral) under stress-strain envelope for an unconfined compression test. This method provides a better understanding between performance and the main mechanical character of CIPB. Compressive strength, splitting tensile and flexural tensile strengths, rebound hardness and abrasion resistance tests at 3, 7, 28, 90 and 180 days were carried out. The test results showed that fly ash (FA) and blast-furnace slag (BFS) can replace the cement by amounts of 10-20%, 30-40% of mass, respectively. This helps to produce CIPB with lower cost and better engineering properties. The relationship between SEdes, strength, hardness. and abrasion are defined for CIPB. (C) 2007 Elsevier Ltd. All rights reserved.