Analysis of Additives in Gypsum Coatings Based on Melamine, Polycarbonate Salts, Polycarboxylate, and Polycarboxylic Acids

Abstract

In this paper, we evaluate different gypsum coating additives that are available on the market, which are categorized by their chemical bases. The results will serve as a reference for future investigations of new additive bases in order to improve the properties of gypsum. As such, the objective of the this study is to assess the workability, mechanical behavior, and crystalline structure of calcium sulfate combined with different retarding and fluidifying bases, including melamine bases, which have a compressive strength of 19.32 N/mm2 and handling times with polycarbonate salts of up to 117.58 min. The following study presents the results of standard mechanical tests, analyzing semi-hydrated calcium sulfate (without additives) as a reference, along with the addition of melamines, synthetic melanin polymers, polycarbonate salts, polycarboxylates, and a polycarboxylic acid (citric acid). We already know that the addition of these additives will modify the mechanical properties of calcium sulfate, such as the Shore C surface hardness, flexural strength, modulus of elasticity, and compression resistance, which is the object of this study.

Evaluating Sisal Fiber-Reinforced Gypsum Composites for Water Absorption and Mechanical Performance

“…Te sisal fber increases the stifness of the sisalgypsum composites which may be the reason for the increase in heat distortion temperature due to the stabilized cellulose molecules' intramolecular hydrogen bonds which may inhibit thermal expansion along the cellulose chains, improving the lignocellulosic sisal fber thermal stability. Similar results were reported by the authors in [23][24][25][26][27].…”

“…Te mechanical and water absorption properties of the sisal-gypsum composites were studied using impact, hardness, and water absorption tests. Representative specimens from various sections of the developed sisal-gypsum composite were prepared according to ASTM D6110, ASTM D785, and ASTM D570-98 to examine the impact strength, hardness, and water absorption of the prepared composites, respectively [25][26][27][28][29]. Impact strength is a material's capability to resist a sudden applied load or force.…”