Acoustic performance of the double C-block : the tune of sustainable design

Abstract

Limestone masonry walls are a common building elements used in the local construction industry. However, over the last three decades, the construction industry in Malta has witnessed a shift from quarried limestone to Hollow Concrete Blocks (HCB’s). The latter becoming the more popular choice of structural element. This material, even though it is structurally efficient, has a different performance when compared to its predecessor. Although produced in same block dimensions, the internal voids, significantly a lessens the wall’s acoustic performance. Since the local building typology mainly consists of low medium rise buildings, HCB’s are identified as the ideal choice of Concrete Masonry Units (CMUs), albeit with a loss of thermal and acoustic performance. Therefore, an area of research has been identified to upgrade the HCB in order to produce an innovative more compact block that is equally load-bearing, yet with enhanced thermal efficiency, that also inhibits noise transmission through the building envelope. This promotes a more resource-efficient design solution, all to the tune of sustainable design. The Double C Block (DCB) is an ongoing project by the Department of Environmental Design at the Faculty of the Built Environment, University of Malta. It is intended to be an upgraded version of the commonly used Hollow Concrete Block (HCB) by improving the thermal and soundproofing quality of a wall without compromising its load-bearing capacity. This research is of interest because as the construction industry continues to grow and develop, so should the overall performance standard of the building envelope, in line with EU and international standards, aimed at reducing a building’s carbon footprint. This can be achieved by using prefabricated blocks with ready in-built insulation. In this context, this dissertation attempts to explore how different masonry wall constructions and materials influence the sound transmission through a typical wall: a single leaf wall built from the innovative Double C Block (DCB) was tested and compared to a notional wall, built in the standard hollow core block (HCB). Their noise attenuation was examined under laboratory conditions and compared against field experiments, in line with ISO standards, namely ISO 10140-2 and ISO 16283-3 standards respectively. ISO 171-1 standard was then followed to calculate the single unit rating results. Although some fine tuning to the lab experiments is still necessary, the results obtained are promising, with the DCB already exceeding performance over the conventional HCB. This should augur well for the use of the DCB in facades against the element traffic noise, as well as for third party walls between apartments.