SOUND MITIGATING CONCRETE
The ubiquity of noise in our quotidian environment has been shown to have serious side effects over the course of an individual’s life. Studies by (Munzel, T.et al.2014) have shown that environmental noise can increase daily tension causing stress, and increases the risk of heart disease. Other effects of noise pollution can lead to auditory fatigue and deafness, physical disorder, affect activities requiring concentration, and even affect the value of property.
Sound is a force that uses pressure to act upon molecules to create waves. The waves that compose audible sounds exist along a specific range of frequency of, 20Hz to 20,000Hz. Frequency measures the size of wavelength - the shorter the wavelength the higher pitched the sound. Sound is measured in terms of Decibels (dB). Decibels measure the intensity of pressure propelling the sound waves. The final metric of sound is in the perceptual measurement, rather than a physical property of sound. Human hearing is most sensitive at the frequency ranges of 2000Hz 0 to 5000 Hz. Several systems of weighting match actual sound pressure levels with human hearing sensitivity to give a rubric that would describe how sound is perceived. The most common weighting is A weighting. The unit is dB(A).
In order to provide a controllable sound mitigating exterior surface, capable of integration into the built and urban fabric most closely associated with high intensity noise pollution environments, a dual strategy is employed. A surface is created that is simultaneously absorbent and diffusive. As an exterior surface that is resistant to the environment, the most plausible material to be moldable and yet feasible for the absorbent is concrete. A special admix is developed that produces a granulated composition for a sandwich panel façade, yet still capable of being cast like traditional concrete panels into a mold that is configured based on sound diffusing geometry. The result is a panel that could be used as either a concrete façade system or as a Mechanically Stabilized Earth (MSE) to provide controlled mitigation of sound in an urban context.