A novel vermiculite/ vegetable polyurethane resin-composite for thermal insulation eco-brick production

Affordable houses with thermal insulation materials are an efficient and creative solution for needy populations in regions where high temperatures are a public health and economic problem. In this sense, the present work had as objective to present, produce, and evaluate composites of raw vermiculite (RV) or expanded vermiculite (EV) in a vegetable polyurethane resin (VPR) matrix as thermal insulation eco-bricks. First, RV and EV were characterized by thermogravimetry (TG/DTG), X-ray fluorescence spectrometry (XRF), and scanning electron microscopy (SEM) coupled to energy-dispersive X-ray spectroscopy (EDX). Second, VPR was analyzed by TG/ DTG. Then, materials were mixed and conformed into bricks in concentrations of 70, 80, and 90 wt % of raw vermiculite, and also 70, 80, 90 wt % of expanded vermiculite. The produced bricks were submitted to an alterability test with immersion into chemical reagents (ASTM D 543), humid atmosphere attack (NBR 8095), UV exposure (ASTM G 53), compressive test (ASTM D 695), physical indexes (NBR 12766), thermal insulation test, and TG/flammability test (ASTM D 635). Analysis of Variance (ANOVA) derived by a mixed 2 and 3-level design was utilized. Only 70% raw vermiculite passed NBR 8492 (soil-cement brick - dimensional analysis, compressive strength determination and water absorption - test method) and for this reason, was chosen for prototype production. Vermiculite react more with acid solutions. Vermiculite incorporation improves thermal stability and flame retardancy. 70 wt % RV brick was able to reduce 65% of the temperature, with good compressive strength (4.12 MPa) and low specific mass (1.47 g cm-3).

Automated summary

Affordable houses with thermal insulation materials using raw and expanded vermiculite combined with vegetable polyurethane resin were effectively tested in reducing temperature and improving compressive strength in high temperature regions. The study found that incorporating vermiculite into the materials enhanced thermal stability and flame retardancy, with 70% raw vermiculite bricks showing promising results.