The effect of pumice powder on the self-compactability of pumice aggregate lightweight concrete

This paper presents the results of an experimental study about the effects of pumice powder, different water/(cement + mineral additive) ratios and pumice aggregates on some physical and mechanical properties of self-compacting lightweight aggregate concrete. In this study, pumice was used as lightweight aggregates. Several properties of self-compacting pumice aggregate lightweight concretes such as unit weight, flow diameter, T50 time, flow diameter after an hour, V-funnel time and L-box tests, 7, 28, 90 and 180-day compressive strength, 28-day splitting tensile strength, dry unit weight, water absorption, thermal conductivity and ultrasonic pulse velocity tests were investigated. For this purpose, 24 series of concrete samples were prepared in two groups. In the first group, pumice aggregate at the rate of 100% was used for the production of self-compacting lightweight aggregate concrete with constant w/(c + m) ratios as 0.35, 0.40 and 0.45 by weight. Furthermore as the second group, pumice aggregate was used as a replacement of natural aggregate, at the levels of 0%, 20%, 40%, 60%, 80%, and 100% by volume with fly ash and blast furnace slag mineral additives at the constant rate of 40%. The flow diameters, T50 times, paste volumes, 28-day compressive strengths, dry unit weights, thermal conductivities and ultrasonic pulse velocity of self-compacting lightweight aggregate concrete were obtained in the range of 560-800 mm, 2-11 s, 435-558 l/m(3), 10.5-65.0 MPa, 840-2278 kg/m(3), 0.347-1.694 W/mK and 2611-4770 m/s respectively, which satisfies not only the strength requirement of semi-structural lightweight concrete but also the flowing ability requirements and thermal conductivity requirements of self-compacting lightweight aggregate concrete. (C) 2015 Elsevier Ltd. All rights reserved.