Abstract
Cellular concrete is a lightweight concrete obtained by aerating agent, which produces air-voids into the mixture. This work deals with bond between cellular concrete and steel rebars. Pull-out tests of 4,2 mm diameter rebars partly immersed into concrete cylinders were made. Concrete unit weight variation and setting of a transverse rebar into the concrete cylinder center constitute the variables of the work. Three types of mixture were prepared: one without aerating agent (with a dry unit weight of 2255 kg/m3), and two with different aerating agent rates (with a dry unit weight equal to 1565 and 1510 kg/m3). The study revealed the large decrease of bond stress between 4,2 diameter rebars and cellular concrete, due to concrete unit weight reduction. Transverse rebar introduced into concrete cylinder center increased the ultimate pull-out force of the test: the gain of bond produced by the transverse rebar grew up when the cellular concrete unit weight had been reduced. Therefore, special anchorages (not exclusively straight), permitting bond improvement between cellular concrete and rebars could be a solution to improve the mechanical performance of cellular concrete.
Keywords:
cellular concrete; bond stress; anchoring.
Note: lb: bond length; Ft: pull-out force. All dimensions in cm
Note: lb: bond length; Ft: pull-out force. All dimensions in cm
Note: lb = longitudinal bond length; tb = transversal bond length; Ft = pull-out force. All dimensions in cm
Note: lb = longitudinal bond length; tb = transversal bond length; Ft = pull-out force. All dimensions in cm
Note: drawing out of scale
Note: translation of the rebar (a) without concrete cracking (b)
Note: failure of the longitudinal rebar outside the concrete cylinder (a, b) without concrete cracking (c)
Note: for 78% of the sample, longitudinal rebar translation and transverse rebar bending (a, b) with longitudinal and transverse cracking of concrete (c). For 22 % of the sample, failure at the level of the weld between the longitudinal and transverse rebars (d, e), without concrete cracking (f)
Note: longitudinal rebar translation and transverse rebar bending (a, b) with longitudinal and transverse cracking of concrete (c)
Note: failure at the level of the weld between the longitudinal and transverse rebars (a, b), without concrete cracking (c)
Note: longitudinal rebar translation and transverse rebar bending (a, b) with longitudinal and transverse cracking of concrete (c)
Note: top = top strain gauge; bott. = bottom strain gauge. See Figure 4 for strain gauge locations