A Sound Approach to Concrete: Transforming Concrete Through Shape and Porosity for Acoustical Reflection, Diffusion, and Absorption

Abstract

Opening Figure. Material science and data-driven design. Close up image of designed and fabricated Acoustically Diffuse and Absorbent Lightweight Aerated Concrete (ADALAC) panels showing surface articulation. (Credit: Emily Butko)Concrete can be enhanced through admixtures and fabrication techniques to achieve various acoustically based criteria and allow a radical departure from typical surface density and continuity. In the work presented here, faculty, students, and industry partners experimented with concrete admixtures, overall surface articulation, and form to provide prototypical concepts which support acoustical interactions. Benchmarking against various published resources which define (1) the acceptable ranges of acoustical criteria and (2) the relationship between the aural environment and personal productivity, retention, and performance confirms the research focus on acoustical linkages between surface, form, and cubic volume using aerated-meaning pervious/porous/cellular-concrete. 12 An earlier publication by the current author explains the research context and data collection process. 13 Acoustical properties of materials and spatial volume can either support or detract from the function of a room or transfer sound to other spaces. Without attention to the acoustical properties of selected materials of the enclosure, the most common result is a persistence of sound known as reverberation, with Reverberation Time (RT) measured in seconds. Using either the Sabine or Eyring formula 14 to calculate RT offers quantifiable scientific data supporting anecdotal criticisms but does not relate to the shape of the space and associated diffusion. The recently developed Residual Minimization Method allows not only for sound absorption coefficients of similar rooms, but also for their geometry, volume, or the diffusion of the acoustic field. 15 Similarly, laboratory tests and software analysis of design mixes and prototypical panels defined in this study resulted in values relating diffusion and absorption.

Evaluation of the dynamic response for scaled models of shaped concrete floor slabs

“…Similarly, assessment of the absorptive performance of non-traditional structures may be valuable for designers to explore alternatives for improving room acoustics. 54 Lastly, incorporating accurate acoustic objectives can aid in multi-disciplinary studies aimed to determine the overall best performing designs. 55…”