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Effect of Water Content on the Structure and Mechanical Properties of Magnesia‐Phosphate Cement Mortar
Author(s) -
Hall David A.,
Stevens Ronald,
Jazairi Bayhass El
Publication year - 1998
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1998.tb02515.x
Subject(s) - struvite , magnesium , materials science , cement , phosphate , magnesium phosphate , amorphous solid , crystallite , ammonium , water content , porosity , ammonium phosphate , mortar , chemical engineering , mineralogy , nuclear chemistry , chemistry , metallurgy , composite material , organic chemistry , geotechnical engineering , engineering , fertilizer
Magnesia‐phosphate cement mortars, based on magnesia and ammonium dihydrogen orthophosphate, were prepared with water contents (measured as a weight fraction of the dry material) in the range 5% to 12%. It was shown by XRD that the major reaction product was magnesium ammonium phosphate hexahydrate (MgNH 4 PO 4 6H 2 O), also known as the mineral struvite. Evidence was also found to suggest the presence of an amorphous or poorly crystalline phase with a lower degree of hydration in materials prepared with water contents less than 8%. For higher water contents, the excess water gradually evaporated during aging to leave an interconnected fine porous structure which exhibited poor mechanical properties. An increase in the water content from 5% to 12% also led to a significant increase in the crystallite size, from around 0.5 µm to 10 µm.