Transport of Ca+2 and $${{\rm SO}_{4}^{-2}}$$ Ions in Porous Media of Clay Product and Its Association with the Efflorescence Phenomenon

Abstract

This study investigates the displacement of SO −2 4 and Ca +2 ions in a red-clay ceramic, simulating the process of efflorescence. Ceramic bodies were molded (70 × 27 × 9mm 3 ) by vacuum extrusion formulated with different contents of CaSO 4 · 2H 2 O (0, 2, 4, 8, and 16% in weight) and burnt at different temperatures (800, 850, 900, and 950 • C) for 12 h. Ceramic bodies were characterized in terms of water absorption, apparent porosity and pore size distribution. Efflorescence was evaluated according to the norms of ASTM C67/2003 and by testing the solubilization of SO −2 4 and Ca +2 ions after 1 h with the ceramic bodies immersed in hot water as well as after 7, 14, and 28 consecutive days with the ceramic bodies immersed in cold water. In the quantification of efflorescence, a new image analysis methodology was developed by using the graphic software Image Tools 3.0. The results allowed in establishing a relationship between the efflorescence of the investigated ions, physical properties (water absorption and apparent porosity), pore size distribution, and solubilization.

Development and validation of an analytical method for the extraction and quantification of soluble sulfates in red clay

“…In most cases, the ceramic materials for facade that are manufactured in the region, such as bricks, knits, tiles, etc., present efflorescences, fundamentally due to the migration of soluble salts like sulphates, nitrates and chlorides from different origins [5][6][7][8][9], which pose on the material surface in the form of stains, generally whitish [10][11][12][13]; this pathology makes the decrease of the aesthetic quality thereof, which means depretiation in the cost of the finished product, which leads to economic losses for entrepreneurs of the sector [14,15].…”