The use of tyre waste has become common in various engineering applications as a light weight fill material, vibration isolation, noise absorption and other environmental benefits. Several studies are available on use of recycled waste as an alternative to the natural materials in the construction field. In this study, the effect of tyre crumbs on the specific gravity of Construction Demolished Waste (CDW) is investigated. CDW is grouped into three different groups based on size of particles, Group 1 (0.075 mm–0.3 mm), Group 2 (0.3 mm–1.18 mm) and Group 3 (1.18 mm–4 mm), respectively. Locally available tyre crumbs of size range between 0.075 and 4 mm is used in the study. The tests on specific gravity of CDW are conducted using pycnometer method. Further, an attempt is made to understand the combined effect of specific gravity on composite of CDW and tyre crumbs as studies available on combined effect of these two materials are not available in the literature. To address the composite effect, experiments are conducted using water pycnometer as well as using ethyl alcohol pycnometer as tyre crumbs floats on the surface of water. The obtained values of specific gravity is compared considering the group effect and combined effect of the construction waste. Further, a correlation is predicted using the obtained values of specific gravity determined using water and ethyl alcohol pycnometer for converting the specific gravity of the composite mixture of tyre and construction waste of different proportions.