Further Insights Into Calcium Sulfoaluminate Cement Expansion, Craig W. Hargis, Barbara Lothenbach, Christian J. Müller, Frank Winnefeld
Mar 2019
Further Insights Into Calcium Sulfoaluminate Cement Expansion, Craig W. Hargis, Barbara Lothenbach, Christian J. Müller, Frank Winnefeld
Craig Hargis
There is still an ongoing debate on the mechanisms of expansion of calcium sulfoaluminate (CSA) cements, which can be either favourable, for example, in shrinkage compensating construction materials, or deleterious in cases of excessive expansion. In order to expand on previous studies, CSA cements with molar ratios (M) of calcium sulfate/ye’elimite of 0·1, 1, 1·5 and 2 were investigated from 30 min to 182 d. All systems showed expansion, and expansion was found to increase with increasing gypsum content. The sample with M= 2 showed a high expansion and severe cracking after 1 d of hydration. Based on the pore …
Effect Of Volcanic Ash Pozzolan Or Limestone Replacement On Hydration Of Portland Cement, Kemal Celik, Craig W. Hargis, Rotana Hay, Juhyuk Moon
Dec 2018
Effect Of Volcanic Ash Pozzolan Or Limestone Replacement On Hydration Of Portland Cement, Kemal Celik, Craig W. Hargis, Rotana Hay, Juhyuk Moon
Craig Hargis
The replacement of Portland cement (PC) with either supplementary cementitious material (SCM) or fillers, such as natural pozzolans (NP) or limestone powder (LP) respectively, is known to affect the chemical properties of concrete, thus influencing its fresh and hardened properties. This study investigated the effects of volcanic ash NP or LP on setting time, normal consistency, hydration, and strength properties of cement paste and mortar while following the chemical changes that were a direct result of the substitution. While both materials were found to increase water demand, NP at 30% and 50% replacement levels increased setting time while LP at …
The Effect Of Water And Gypsum Content On Strätlingite Formation In Calcium Sulfoaluminate-Belite Cement Pastes, Yeonung Jeong, Craig W. Hargis, Sung-Chul Chun, Juhyuk Moon
Jan 2018
The Effect Of Water And Gypsum Content On Strätlingite Formation In Calcium Sulfoaluminate-Belite Cement Pastes, Yeonung Jeong, Craig W. Hargis, Sung-Chul Chun, Juhyuk Moon
Craig Hargis
The main objective of this study was to investigate the phase and strength development of calcium
sulfoaluminate-belite (CSAB) cement pastes with different amounts of gypsum and water.
Thermodynamic modeling and a series of experiments including X-ray diffraction (XRD), thermogravimetric analysis, isothermal calorimetry, and compressive strength tests were performed. Decreasing the mixing water increased the strength of CSAB pastes, but decreased the degree of hydration. Interpretation of the early age XRD results and thermodynamic modeling suggested the formation of a meta-stable phase from the hydration of belite, possibly C-(A)-S-H, which transformed into strätlingite at later ages only in the samples with …
Effect Of Calcium Carbonate Fineness On Calcium Sulfoaluminate-Belite Cement, Yeonung Jeong, Craig Hargis, Sungchul Chun, Juhyuk Moon
Jul 2017
Effect Of Calcium Carbonate Fineness On Calcium Sulfoaluminate-Belite Cement, Yeonung Jeong, Craig Hargis, Sungchul Chun, Juhyuk Moon
Craig Hargis
This study investigated the hydration characteristics and strength development of calcium
sulfoaluminate-belite (CSAB) cements incorporating calcium carbonate (CC) powders with various
particle size distributions and different gypsum amounts. In general, the CSAB hydration was
accelerated by the CC powder, but the acceleration and resulting strength improvement were
more effective with finer CC powder. Regardless of the fineness of the CC powder, it took part
in the hydration of CSAB cement, forming hemicarboaluminate and monocarboaluminate phases.
These hydration and nucleation effects compensated for the strength reduction from decreased
cementing components (i.e., dilution effect) when finer CC powders were used, while they …
Aggregate Passivation: Lithium Hydroxide Aggregate Treatment To Suppress Alkali-Silica Reaction, Craig Hargis, Maria C.G. Juenger, Paulo J.M. Monteiro
Aug 2013
Aggregate Passivation: Lithium Hydroxide Aggregate Treatment To Suppress Alkali-Silica Reaction, Craig Hargis, Maria C.G. Juenger, Paulo J.M. Monteiro
Craig Hargis
Alkali-silica reaction (ASR) continues to be a concrete durability problem despite the many physical and chemical mitigation techniques known to successfully prevent it. The research presented herein tested a new method to limit ASR: aggregate passivation. A lithium silicate layer was created on reactive natural siliceous aggregate surfaces by treating the aggregates in a lithium hydroxide solution prior to use. A 4 M LiOH treatment was found to be superior to a 2 M LiOH treatment in producing a lithium silicate passivation layer and in reducing expansion due to ASR. The use of passivated aggregates greatly reduced expansion in accelerated …
Reply To The Discussion Of The Paper “Understanding Expansion In Calcium Sulfoaluminate-Belite Cements”, Irvin A. Chen, Craig W. Hargis, Maria C.G. Juenger
Dec 2011
Reply To The Discussion Of The Paper “Understanding Expansion In Calcium Sulfoaluminate-Belite Cements”, Irvin A. Chen, Craig W. Hargis, Maria C.G. Juenger
Craig Hargis
Reply to the discussion of the paper “Understanding expansion in calcium sulfoaluminatebelite cements” by G.L. Valenti, M. Marroccoli, M.L. Pace, A. Telesca.
