Latex and acrylic based waste paint as admixture in concrete masonry blockfill

by Haigh, Christopher John

A significant volume of waste latex and acrylic paint exists in New Zealand, with the rate of supply growing at a substantial rate. This waste stream, once destined for landfills, has the potential to be a useful ingredient in cementitious applications. The study reported herein specifically investigated the use of waste paint as a polymer admixture in concrete masonry blockfill. Polymer concrete is not a new concept and has been used in practice for over 70 years. The success of polymeric admixtures is largely due to their ability to increase the workability of concrete and to reduce drying shrinkage. The objective of this study was to produce a blockfill mix capable of maintaining or improving the properties of the hardened material whilst increasing the efficiency of the construction process.

A blockfill mix design was created with the assistance of an industry partner and a number of tests were conducted to evaluate the various fresh and hardened concrete properties whilst investigating an optimum dosage of waste paint. Study into the fresh properties of blockfill focused upon workability, with specific attention given to investigating the change in rheological properties. Compressive strength, tensile strength, drying shrinkage and seismic performance were studied to assess the hardened properties of the blockfill. Industry trials were conducted to ensure that the material properties determined within the laboratory could be achieved at a larger scale.

It was established that waste latex and acrylic based paint was a suitable additive to concrete masonry blockfill, resulting in maintained strength and improved workability, providing a viable substitute to standard chemical admixtures currently used to achieve comparable results. Increased water content was required to ensure that the waste paint was distributed evenly within the mix, which led to maintained compressive strength without the addition of excessive air content. Pseudo-static testing of a reinforced concrete masonry wall confirmed that the seismic performance of the blockfill was comparable to that measured when using a standard blockfill.