Determination of reflectivity of concrete slabs applied with paint added with powdered Placuna placenta shell as additive

JOHANNA MARIE L. APDON, FERGIE JOHN O. FRANGE, EUNICE LYN F. SALISTRE, and ARIS C. LARRODER
Philippine Science High School – Western Visayas Campus, Brgy. Bito-on, Jaro, Iloilo City 5000, Department of Science and Technology – Science Education Institute, Philippines

Abstract
Retroreflectors are used as additives to paint in order to increase their reflectivity. A typical example would be glass beads whose vitreous luster and spherical shape make them efficient retroreflectors. These properties allow any surface where it has been applied on to absorb less heat and reflect more light. Placuna placenta shells are vitreous and can be powdered into spherical shape which can serve as efficient retroreflectors. The shells were ground into powder, sieved and then added with varying ratios to commercial white paint before being tested if they still pass the national paint standards. Each paint setup was tested for its albedo and temperature to determine its reflectivity. Results revealed that even after adding the Placuna placenta shell powder to the commercial paint, all modified paints still managed to meet the national standards for paint tests. Analysis of the photos taken of the setups showed that those with the highest ratio of shell powder exhibited significantly higher reflectivity. The temperature difference between setups, however, was not statistically significant. Therefore, powdered Placuna placenta shells can be used indeed as a paint additive and that it increases the reflectivity of the paint.

Keywords: Placuna placenta, solar retroreflector, paint additive, paint tests, reflective paint