Evaluation of Treated Calcinied Clay Obtained from Local Resources for Use as Supplementary Cementitious Material in Concrete
"The purpose of this study is to produce calcined clay from local resources and to investigate its performance for concrete uses.
Development of construction materials which offers environmental and technical benefits is nowadays a new challenge. Some of these supplementary cementitious materials (SCM) are used to replace part of the Portland cement to reduce the CO2 emission and energy consumption during the cement production. Active Metakaolin is one of these cementitious materials. Metakaolin is obtained from thermal treatment of kaolin Clay, the process which is called calcination, where the water contained in mineral kaolinite is driven off, resulting in the formation of amorphous alumino-silicate which is the Metakaolin. This reaction occurs under specific conditions of heating and cooling. Heating time and cooling temperature, as well as the ambient conditions of the treatment process are the parameters that affect the quality of the end product. The activity index of pozzolanic Metakaolin will indicate if it can be used as SCM to partially substitute cement in concrete or not. This test will be performed in this research to compare between the different treatment methods.
During the cement hydration process, water reacts with Portland cement and forms calcium-silicate hydrate (CSH) in addition to a by-product which is the lime. When added to concrete, lime will react with Metakaolin to form additional CSH which densify the cement past leading to a stronger concrete.
The objective of this research is first to specify the optimized treatment conditions of kaolin clay and especially the heating temperature and the exposure period to obtain active Pozzolanic Metakaolin. The second one is to evaluate the physical and chemical properties of the calcined kaolin clay obtained after treatment in the aim of using it in concrete to improve its performance in terms of strength and durability.
Bashar Aasem Abdallah
Dr. Ousama Baalbaki, Dr. Adel Elkordi