Mechanical and Durability Properties of Different Types of Concrete using Limestone Calcined Clay Cement

Abstract

Cement is an inveterate material to satisfy global housing and infrastructure needs. Hence in order to meet the overwhelming demand sustainably the use of blended cement can be more ecological and economical. The use of Supplementary Cementitious material seems to be a viable option; however, it is limited by the forecasted supply of commonly used SCMs notably slag and fly ash. Therefore, the use of other possible options available in large quantities globally should be acknowledged. The use of calcined clay as pozzolans has been known for some time, but the substitution is practical only up to 30% which does not compensate for the cost of calcination. Recently a coupled substitution of limestone along with calcined clay was investigated. With use of limestone, an additional 15% of clinker can be replaced with no decrease in mechanical performance. The mechanical performance and durability aspects are the two fundamental requirements for any binder system to be substantiated and well received in the present industrial scenario. The present study focuses on the potential of Limestone Calcined Clay Cement for use in structural concrete. The newly developed system is compared with other well-established binding systems like Ordinary Portland Cement (OPC) and Portland Slag Cement (PSC). Four types of concrete mixes have been targeted for the present work, based on achieving an equivalent strength grade (M20, M40, M60 and M80) for each binder system. The mechanical properties such as compressive strength, elastic modulus and shrinkage are to be assessed for different curing ages. Along with this the durability performance pertaining to various transport mechanism are also analysed. Chemical Attacks, water impermeability, water sorptivity, accelerated carbonation, rapid chloride penetration test and chloride migration co-efficient are the key evaluation parameters for durability performance. The presence of calcined clay and limestone contributes to the strength development, as they undergo a synergistic reaction to form space filling carboaluminate hydrates, hence the anticipated performance of LC3 systems in terms of strength development should be comparable with other binder systems. Due to a finer pore structure, added fineness due to calcined clay and limestone (filler effect); LC3 systems are expected to perform better than other binder systems with respect to various transport mechanisms.