Use of micro‐Raman spectroscopy to study reaction kinetics in blended white cement pastes containing metakaolin

Abstract

Curing temperature is known to play an important role in the formation, development, and stability of the hydrated phases appearing during pozzolanic reactions (chemical reaction between puzzolanic addition, metakaolin (MK), and calcium hydroxide from cement hydration). A typical example of this important reaction is to be found in metakaolin-bearing cement pastes, characterized by hexagonal phases whose thermodynamic stability declines with rising temperature. These phases cannot be exhaustively researched with traditional techniques (such as X-ray diffraction) due to their poor crystallinity. Consequently, micro-Raman spectroscopy was used in the present study to explore the behavior of white cement paste blends containing 0, 10, and 25% MK at two curing temperatures (20 and 60 • C). This led to the identification, for the first time using Raman spectroscopy, of phases C 2 ASH 8 1 (stratlingite) and C 3 ASH 6 , which appear in the MK-white cement reaction. The C-S-H gel formed was characterized by Q 1 dimers and a C/S ratio of 1.3-1.5. Raising the curing temperature favored the formation of C 4 AH 13 .

Accelerated carbonation effect on behaviour of ternary Portland cements

“…Ternary Portland cement (TPC) was prepared by using a commercially available ordinary Portland cement (OPC) classified as CEM I 52.5 N, activated paper sludge (APS) [17][18][19][20][21][22][23][24][25][26][27] and fly ash (FA) from coal combustion ASTM class F. The OPC was supplied by Financiera y Minera (Italcementi group). The APS was obtained by controlled calcination of paper sludge in our laboratory, by means of an electric furnace at 700°C for 2 h, as described in previous work [27].…”

Paper sludge, an environmentally sound alternative source of MK-based cementitious materials. A review

“…Metakaolinite (MK), as a product of the controlled activation of natural kaolin long known to have pozzolanic properties [1][2][3][4][5], has merited inclusion in standards on cement manufacture and use for many decades [6]. For one reason or another, however (energy demand, environmental policies to protect natural areas and the existence of less expensive pozzolans), it has seldom been used in commercial cement manufacture.…”

Evolution of Mineralogical Phases by27Aland29SiNMRinMK‐Ca(OH)2System Cured at 60°C

“…During the past few years, the kinetic of the metakaolin pozzolanic reaction has been the objective of numerous investigations …”