Gypsum-Based Boards Made from Mixtures of Waste Cellulosic Sources: Part 1. Physical and Mechanical Properties

It was realized that post-consumer waste paper, old corrugated container (OCC) and secondary fiber addition (cellulosic additives) to gypsum in panel structure negative impact on Thickness Swelling (TS) values in water. However, highest TS values of 23.32% (A6) in A-type, 12.76 (B6) in B-type and 7.79% (C6) in C-type experimental boards found at similar proportions (50:50 w/w) of gypsum and cellulosic additives while the lowest with control sample that was only 1.88%. Moreover, the boards produced by secondary fiber/gypsum mixture (C type boards) under similar ratios (w/w) were found to higher IB strength than others. The highest IB strength value of 0.60 N/mm2 found for C3 board while the ratio of the secondary fiber in the mixture to be more than 20% negative effects on IB values to a certain extent. The addition of all three cellulosic sources to the gypsum structure increases the bending strength properties some level. At 10% (A2: 6.59 N/mm2) and 50% (A6: 6.44 N/mm2) proportion levels, A-type boards show higher bending strengths than the B- and C-type boards. In all manufacturing conditions and board types, the natural weathered boards have always shown lower hardness properties than counterpart control samples