Relationship between gypsum content, porosity and strength in cement. I. Effect of SO3 on the physical microstructure of Portland cement mortars

✍ Scribed by Riccardo Sersale; Raffaele Cioffi; Giuseppe Frigione; Fortunato Zenone

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 384 KB
• Volume: 21
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(91)90038-j

✦ Synopsis

The experimental investigation is part of a wider research programme, addressed to correlating the modifications in the physical microstructure, due to gypsum addition, with the mechanical behaviour of cement mortars. This fast paper reports on the examination of a series of mortars manufactured with Portland cement, SO3 content ranging between 1.5 and 4.5%, cured 3 and 28 days. An outline of the tests procedure is also given. By means of mercury porosimeter analysis it has been pointed out that, in standardized working conditions, a content of about 2-3.5% SO3 promotes a shifting of the pore size distribution to lower values, ranging between 100 and 1000/~, as well as a variation in total porosity. This latter appears to be the main factor governing the influence of SO3 on the compressive strength of Portland cement mortars, since the variation in pore size distribution alone seems confined to a sphere negligibly affecting strength.