General-purpose and thin layered masonry mortars produced with limestone calcined clay (LC3) cement

The high energy consumption and CO₂ emissions associated with clinker production in traditional Portland cement (PC) have necessitated the development of sustainable binders. In this context, Limestone Calcined Clay Cement (LC3) emerges as a prominent alternative with a low carbon footprint. The valorization of low-grade clays in LC3 mixtures offers more beneficial solutions in terms of costs and environmental impacts. The primary objective of this thesis is to develop general purpose and thin-layer masonry mortars using LC3 binders produced with low-grade clays of Turkish origin. The performance of the developed general purpose and thin-layer masonry mortars was compared with existing commercial lime-added cement mortars used as references, in accordance with the relevant standards. For this purpose, ultra-low clinker LC3 mixtures, comprising only 10% PC in the binder system with the remaining components consisting of calcined low-grade clay, limestone, and gypsum, were developed for general purposes and thin-layer masonry mortars. The experimental program included the grinding of clays, their calcination at 650 °C, and fineness optimization via hybrid grinding for the raw materials, respectively. Subsequently, the developed general purpose and thin-layer LC3 masonry mortars were tested within the scope of TS EN standards to determine fresh state properties (flow, workability life, air content, chloride content) and hardened state properties (dry bulk density, capillary water absorption, compressive strength, initial shear strength, flexural bond strength, thermal conductivity, water vapor permeability, and reaction to fire). The experimental studies involved extensive preliminary research, particularly regarding the reduction of clinker content while ensuring the desired performance levels. The 28-day compressive strengths of the general purpose LC3 masonry mortars containing 10% PC developed within the scope of the scope of the thesis (ranging from 6.7 MPa to 7.5 MPa) demonstrated similar performance to the average compressive strengths of the commercial lime-added masonry mortars used as references (7.0 MPa). In the thin-layer LC3 masonry mortars, 28-day compressive strengths were obtained in the range of approximately 5.9 MPa to 7.2 MPa, showing similar compressive strength to the reference thin-layer mortars (average 6.4 MPa). Although the capillary water absorption coefficients in the LC3 general purpose and thin-layer masonry mortars were slightly higher compared to the reference mixtures, the flexural bond strength and initial shear strength performances indicated that they provided high adhesion and load transfer, particularly for certain LC3 masonry mortars. Overall, the findings reveal that general purpose and thin-layer LC3 masonry mortars formulated with low-grade local clays, with PC content reduced to as low as 10%, are viable as an environmentally reduced-impact option capable of meeting technical requirements in terms of both mechanical properties and building physics.