Numerous recurrent situations following mixing and pumping of mortars and concretes cause degradation of fluidity and hardening characteristics. Which, in turn, lead to adverse effects on the quality of workmanship and structural defects. Nonetheless, relatively little research on the mixing and pumping energies used for the onsite transport and preparation of mortar or concrete has been directed at the core reasons or mechanisms for changes in technological properties. This dissertation describes and explains the effects of various mixing and pumping parameters on the mortar characteristics in a field trial and on a laboratory scale. Observations using a rheograph revealed that shearing action does exhibit the most pronounced influence on the characteristics of mortars during the pumping. The performed investigations indicate that higher shearing actions, for example, excessive mixing duration and long-distance pumping lead to reduced flowability, accelerated and increased hydration rate, increased early compressive strength and early-age shrinkage. From these findings, the underlying mechanism responsible for acceleration and increase of hydration rate is pinpointed as: the increased dissolution from the active surface area due to the destruction of the protective superficial layers of cement grains, as well as a transition from flocculation to dispersion. The creation of new surfaces leads to further consumption of active super plasticizer in solution phase and to subsequent degrading changes in fluidity (decreasing flowability). The degradation of fluidity and densification of microstructure provoked by the hydration changes do increase the early age shrinkage of mortar.

Numerous recurrent situations following mixing and pumping of mortars and concretes cause degradation of fluidity and hardening characteristics. Which, in turn, lead to adverse effects on the quality of workmanship and structural defects. Nonetheless, relatively little research on the mixing and pumping energies used for the onsite transport and preparation of mortar or concrete has been directed at the core reasons or mechanisms for changes in technological properties. This dissertation describes and explains the effects of various mixing and pumping parameters on the mortar characteristics in a field trial and on a laboratory scale. Observations using a rheograph revealed that shearing action does exhibit the most pronounced influence on the characteristics of mortars during the pumping. The performed investigations indicate that higher shearing actions, for example, excessive mixing duration and long-distance pumping lead to reduced flowability, accelerated and increased hydration rate, increased early compressive strength and early-age shrinkage. From these findings, the underlying mechanism responsible for acceleration and increase of hydration rate is pinpointed as: the increased dissolution from the active surface area due to the destruction of the protective superficial layers of cement grains, as well as a transition from flocculation to dispersion. The creation of new surfaces leads to further consumption of active super plasticizer in solution phase and to subsequent degrading changes in fluidity (decreasing flowability). The degradation of fluidity and densification of microstructure provoked by the hydration changes do increase the early age shrinkage of mortar.

This study aims to provide a comprehensive understanding of the characterization and structuring of ternary binders composed of Portland Cement (PC), Calcium Aluminate Cement (CAC), and Calcium Sulfate (CŜ). Ternary binders exhibit unique characteristics that make them suitable for various advanced technological applications. The combination of these three components enhances early setting and strength development, and reduces shrinkage, while also contributing to lower CO₂ emissions compared to plain Portland cement. The hydration mechanisms of ternary binders (PC–CAC–CŜ) involve complex chemical interactions. PC primarily contributes to long–term strength and durability, CAC accelerates early strength development, and CŜ regulates setting time and moderates shrinkage. These combined effects lead to a synergistic improvement in the performance of the ternary binders. With the addition of Supplementary Cementitious Materials (SCM), these binders exhibit notable changes in fresh and hardened properties, and, most importantly, achieve a lower carbon footprint. The methodology chosen for this investigation involves Design of Experiments (DOE) and Principal Component Analysis (PCA), aiming to statistically understand and refine the properties of ternary binders. The research is conducted over multiple stages, each using varied DOE methods to investigate the effects of several parameters, including binder composition, SCM, cement replacement ratio, specific types of CAC and CŜ, and the addition of chemical admixtures. Each of these factors is analyzed for its impact on specific properties such as workability, setting time, hydration kinetics, dimensional stability, compressive strength, and phase assemblage. A particularly advanced aspect of this research is the investigation of chemical admixtures and their interaction with ternary binders. Furthermore, the study incorporates a rigorous analysis using the orthogonal Taguchi design, comparing it with findings from the comprehensive previous investigation. The main goal is to determine whether the Taguchi design can optimize the process, potentially indicating significant reductions in experimental runs, labor hours, and overall costs. This thesis offers significant insights into optimizing ternary binders for enhanced performance and sustainability. By understanding the relationship between rheological parameters and physicochemical microstructure development, the research contributes to the advancement of construction materials with improved early strength, reduced shrinkage, and lower environmental impact. The findings have important implications for the development of high–performance, sustainable construction materials suitable for a wide range of applications.:Acknowledgements i Abstract ii Glossary vi 1 Introduction 1 1.1 Background 1 1.2 Research motivation and objectives 2 1.3 Thesis outline 3 2 Literature review 5 2.1 Portland Cement 5 2.1.1 Hydration of Portland Cement 6 2.2 Calcium Aluminate Cement 9 2.2.1 Hydration of Calcium Aluminate Cement 10 2.3 Calcium Sulphate 11 2.4 Ternary binders 14 2.4.1 Hydration and technological properties 14 2.5 Supplementary cementitious materials 20 2.6 Chemical admixtures 22 2.6.1 Superplasticizers 23 2.6.2 Viscosity Modifying Agents (Stabilizers) 24 2.6.3 Accelerators 24 2.6.4 Retarders 25 2.7 Statistical models 26 2.7.1 Design of Experiments (DOE) 26 2.7.1.1 Factorial design 27 2.7.1.2 Fractional factorial design 28 2.7.1.3 Response surface method 28 2.7.1.4 Mixture design 29 2.7.1.5 Taguchi method 30 2.7.2 Principal Component Analysis (PCA) 31 3 Analytical methods 32 3.1 Flow test 32 3.2 Setting time 32 3.3 Isothermal calorimetry 32 3.4 Length change 33 3.5 Compressive strength tests 34 3.6 X–Ray diffraction 34 4 Materials 36 4.1 Characterization of the raw materials 36 4.2 Selection of the mix design and the sample preparation 37 4.3 Schematic design 38 5 Step I: Influence of binder content in ternary binders 40 5.1 Mixture design 40 5.1.1 Workability and Compressive strength 41 5.2 Summary 44 6 Step II: Influence of composition, supplementary cementitious materials and cement replacement ratio in ternary binders 45 6.1 Factorial design 45 6.1.1 Workability 46 6.1.2 Initial setting time 48 6.1.3 Compressive strength 50 6.2 Principal Component Analysis 52 6.2.1 X–Ray powder diffraction 52 6.3 Summary 55 7 Step III: Influence of composition, Calcium Aluminate Cement and sulphate source variation in ternary binders 57 7.1 Factorial design 57 7.1.1 Workability 58 7.1.2 Initial setting time 59 7.1.3 Compressive strength 61 7.2 Principal Component Analysis 64 7.2.1 X–Ray powder diffraction 64 7.3 Summary 66 8 Step IV: Influence of chemical admixtures in ternary binders 67 8.1 Response Surface Method (RSM) 67 8.1.1 Workability 69 8.1.2 Initial setting time 70 8.1.3 Compressive strength 72 8.1.4 Hydration kinetic 77 8.1.5 Early age shrinkage 81 8.1.6 X–Ray diffraction analysis 83 8.2 Summary 89 9 Step V: Influence of composition, water content, chemical admixtures, Calcium Aluminate Cement and sulphate source in ternary binders 91 9.1 Taguchi orthogonal array 91 9.1.1 Workability 92 9.1.2 Setting time 93 9.1.3 Compressive strength 94 9.1.4 Hydration kinetic 98 9.1.5 Early age shrinkage 101 9.1.6 X – Ray diffraction analysis 104 9.1.6.1 In–Situ 106 9.2 Summary 111 10 Conclusions and perspectives 113 10.1 Conclusions 113 10.2 Perspectives 117 References 119 Appendix A 130 Appendix B 135