Absorption of pozzolana materials on calcium hydration products of cement

Author(s): Hongbo Zhu, Xian Liu, Peiming Wang, Yong Yuan and Haoxin Li
Paper category: conference
Book title: Microstructural-related Durability of Cementitious Composites
Editor(s): Guang Ye, K. van Breugel, Wei Sun and Changwen Miao
Print ISBN: 978-2-35158-129-2
e-ISBN: 978-2-35158-123-0
Publisher: RILEM Publications SARL
Publication year: 2009
Pages: 125 - 131
Total Pages: 7
Language: English

Abstract: Pozzolana materials can react with calcium hydroxide (CH), which is one of hydration productions of cement. It is well known that the reacting progress perhaps continue for a long time, even decade’s years. Because the inner surrounding of hardened cement is very dry at long age and there isn’t enough liquid to transfer ions of CH from crystal CH to grain of pozzolana materials, it is a question how the pozzolanic reaction takes place. This paper presents a viewpoint that pozzolana with latently hydraulic or pozzolanic is apt to absorb CH crystal to grow around it, and the pozzolana with higher pozzolanic would absorb more CH crystals. Forming progress of hydration productions CH are analyzed according to SEMs of hardened cement paste with ground granulated blast furnace slag and high-calcium fly ash. It shows that minerals with latently hydraulic or pozzolanic would attract CH crystal to grow around them. Obviously, there is hydraulic reaction in the partial surface of grains connecting with CH crystal, little hydration in the part without CH surrounding. It indicates a useful method to advance reactivity of minerals with low activity by ways of increasing their absorbability for CH crystal.
Keywords: cement, pozzolana, hydration production, calcium hydroxide, absorption

Online publication: 2012-05-16
Publication Type: full_text
Public price (Euros): 0.00