The role of silica fume in mortar: Transition zone versus bulk paste modification

✍ Scribed by Menashi D. Cohen; Ariel Goldman; Wai-Fah Chen

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 259 KB
• Volume: 24
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(94)90089-2

✦ Synopsis

The influence of silica fume on mechanical properties of concrete remains an important technical and research topic. In general, silica fume tends to increase ~e strength of concrete. It is generally believed that the main source of the increase in strength is due to the pozzolanic and microfiller effects of silica fume, ref.

(1-3). However, there is some controversy as to whether this strength increase is due to (i) the ability of silica fume to modify the microstructure of the cement pasteaggregate interface (transition zone) -ref.

(1-3) -i.e. transition zone modification, or (ii) the ability of silica fume to enhance the strength of the bulk paste, ref. (4,5), i.e. bulkpaste modification.

The objective of this paper is to report some preliminary results of an experimental program aimed at separating the two possible mechanisms above, transition zone modification and bulk paste modification. This was attempted by testing mortar specimens with varying aggregate size (or aggregate surface area). Other parameters such as water:cementitious materials ratio, paste, and aggregate contents were kept constant. By varying the aggregate surface area one could isolate and quantify the influence of the transition zone on the mechanical properties of the mortar. Consequently, one could separate the effect of silica fume on the transition zone from that on the bulk paste.