TY - JOUR
T1 - Performance of Impure Calcined Clay as a Pozzolan in Concrete
AU - Jafari, Khashayar
AU - Rajabipour, Farshad
N1 - Funding Information:
The authors would like to acknowledge and greatly appreciate the fuding for this research by York Building Products Company, York, PA, and the USDOT’s Center for Integrated Asset Management for Multi-Modal Transportation Infrastructure Systems (CIAMTIS), the Region 3 UTC led by Penn State. The authors also thank Lehigh Cement and BASF for donating cement and chemical admixtures. Finally, the authors would like to thank Mr. Dan Fura for his invaluable help with the experiments in this study.
Publisher Copyright:
© National Academy of Sciences: Transportation Research Board 2020.
PY - 2020/1/27
Y1 - 2020/1/27
N2 - Supplementary cementitious materials (SCMs) are natural or industrial by-product materials which are used to improve the performance, durability, and sustainability of concrete mixtures. Motivated by the recent reports on shortage of conventional SCMs, impure calcined clays (CCs) are receiving attention as abundant alternative pozzolans for concrete. In this study, a clay slurry resulting from washing aggregates in a commercial sand and gravel pit was investigated. This source clay was dried and calcined, and the properties and pozzolanic performance of the resulting CC was evaluated. It was observed that despite having a large (>50%wt.) inert quartz content, the CC met all ASTM C618-19 (AASHTO M295) requirements for natural pozzolan. A pavement-grade concrete mixture containing 20%CC as a cement replacement (by weight) produced desired workability and fresh and hardened air content. Strength development was slightly below the control. The use of CC improved the durability of concrete with respect to chloride penetration, alkali–silica reaction, and drying shrinkage in comparison with a control (100% Portland cement) mixture. In addition, ternary limestone-calcined clay–cement and slag-calcined clay–cement mortar mixtures showed excellent strength development while replacing nearly 50% of the Portland cement.
AB - Supplementary cementitious materials (SCMs) are natural or industrial by-product materials which are used to improve the performance, durability, and sustainability of concrete mixtures. Motivated by the recent reports on shortage of conventional SCMs, impure calcined clays (CCs) are receiving attention as abundant alternative pozzolans for concrete. In this study, a clay slurry resulting from washing aggregates in a commercial sand and gravel pit was investigated. This source clay was dried and calcined, and the properties and pozzolanic performance of the resulting CC was evaluated. It was observed that despite having a large (>50%wt.) inert quartz content, the CC met all ASTM C618-19 (AASHTO M295) requirements for natural pozzolan. A pavement-grade concrete mixture containing 20%CC as a cement replacement (by weight) produced desired workability and fresh and hardened air content. Strength development was slightly below the control. The use of CC improved the durability of concrete with respect to chloride penetration, alkali–silica reaction, and drying shrinkage in comparison with a control (100% Portland cement) mixture. In addition, ternary limestone-calcined clay–cement and slag-calcined clay–cement mortar mixtures showed excellent strength development while replacing nearly 50% of the Portland cement.
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U2 - 10.1177/0361198120953140
DO - 10.1177/0361198120953140
M3 - Article
AN - SCOPUS:85101822712
SN - 0361-1981
VL - 2675
SP - 98
EP - 107
JO - Transportation Research Record
JF - Transportation Research Record
IS - 2
ER -