ABSTRACT
Abstract In this paper mechanical properties and microstructural characterization of lightweight aggregate (LWA) mortar are reported. The mortar mixture included the LWA, silica fume, fly ash, and other pozzolanic materials. A rational mix design procedure for mortars containing LWA and other pozzolanic materials was developed. Microstructural analysis of the mortar containing different amounts of LWA and admixtures was performed. The advantages and drawbacks of using fine lightweight aggregate in mortars are discussed. Keywords: lightweight aggregate, microstructure, mechanical properties, mortar, mix proportioning, pozzolanic materials
1 Introduction Recently, Monteiro et al [1,2] developed a mix design nomogram to determine concrete mix proportion when different performance criteria, such as durability, fracture energy or elastic modulus, are specified. The nomogram also allows the comparison of resulting properties from concrete mixtures with different mix proportions. The lightweight aggregate industry became interested in applying this method for the mix proportioning of LWA mortars and concrete. The industry was particularly interested in optimizing the amount of LWA (coated and uncoated) and of pozzolanic materials such as fly ash and silica fume. A research program [3] was established to determine a rational mix design procedure for mortars containing the lightweight aggregate (LWA) and to determine the effect of the aggregate on mechanical properties of the mortars. A careful examination of the microstructure of the LWA mortar was conducted using secondary and backscattered scanning electron microscopy. Twelve mixtures containing different amounts of the LWA, silica fume, fly ash and other pozzolanic materials were studied.
