Title : RECENT DEVELOPMENTS IN LIGHTWEIGHT AGGREGATE CONCRETES ? UK EXPERIENCES
Authors : P.A. Muhammed Basheer1, Jacek Kwasny2& Kieran Owens3
Publication : December 19-21, 2013
Volume :
Pages : 33-55
Price : 250
Abstract : This paper presents selected findings from a recently finished industry-led research project. The study intended developing structural lightweight vibrated concretes (LWVCs) and lightweight self-consolidating concretes (LWSCCs) incorporating high level replacements of Portland cement (PC) with ground granulated blast furnace slag (GGBS), pulverised fuel ash (PFA) or limestone powder (LSP). Lightweight fine and coarse aggregates manufactured from sintered PFA were used to replace normal weight fine and/or coarse aggregates. In addition, LWVC mixes containing GGBS or PFA were manufactured by adding chemical activator (sodium sulphate) in order to improve the early age compressive strength. They were compared to similar mixes made without the activator and to the lightweight and the normal weight vibrated concretes (NWVC) made with 100% PC. The performance of LWSCC mixes containing GGBS, PFA or LSP was compared to that of normal weight SCC (NWSCC) used by local industries. The suitability of the mixes for structural applications was studied by assessing the hardened density, compressive strength and modulus of elasticity. The results indicated that it was possible to manufacture LWVCs belonging to class D1.6 and LWSCCs in class 2.0. The incorporation of large volumes of PFA and GGBS in LWVCs resulted in a significant reduction of compressive strength, especially at early ages (1-day), but this was improved by the use of the chemical activator. At 1-day, the LWSCCs had similar compressive strength to that of NWSCC, but at the later ages only the mix made with GGBS had a comparable strength. The lightweight concrete mixes were successfully tested for two precasting applications, viz. the use of LWVC to manufacture the FlexiArch system and the utilisation of LWSCC in the production of coffered slab units. Observations made during the manufacture of these products and the outcome of the structural full-scale testing are briefly presented.