Compatibility of Cementitious Materials and Admixtures

Abstract

JOINT TRANSPORTATION RESEARCH PROGRAMThe Joint Transportation Research Program serves as a vehicle for INDOT collaboration with higher education institutions and industry in Indiana to facilitate innovation that results in continuous improvement in the planning, design, construction, operation, management and economic efficiency of the Indiana transportation infrastructure. https://engineering.purdue.edu/JTRP/index_html Published reports of the Joint Transportation Research Program are available at: http://docs.lib.purdue.edu/jtrp/ NOTICEThe contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views and policies of the Indiana Department of Transportation or the Federal Highway Administration. The report does not constitute a standard, specification or regulation. AbstractGrowing demand for creating more sustainable and durable concretes lead to the increased usage of various cementitious materials and chemical admixtures in the mixtures. However, the increased usage of these components resulted in more complex mixtures that sometimes cause unexpected incompatibility problems. This report summarizes the results of the investigation of the parameters that may lead to workability problems, early age hydration irregularities and difficulties in achieving quality air void system in both plain and fly ash cementitious mixtures. The present research work was performed in three major phases and the statistical modeling was used to aid in interpretation. Phase I involved evaluation of more than 100 different paste and mortar mixtures with respect to potential slump loss and hydration irregularities. The results showed that cements with high C3A and low SO3 content were more prone to incompatibility problems. It was also observed that mixes with lignin based water reducing agent (WRA) had higher tendency for rapid stiffening than mixes with polycarboxylate type superplasticizer (PCSP). Increased replacement of cement by class C ashes resulted in the development of abnormal secondary peaks in semi-adiabatic calorimetry curves and accelerated the setting behavior.The focus of phase II was on identifying material combinations that can result in problems related to air void generation and stability. The experiments were conducted on 18 different systems and included determination of foam drainage and foam index parameters. The results show that the amount of air entrainers required to obtain target air percentage, increased with the increase in the fly ash content in the mixture. Lignin based WRA had, in general, a higher air entraining effect than the super-plasticizer when used in combination with air entrainers. Also, five out of the six mixtures with most unstable air void system, identified using the foam drainage experiments, contained the PCSP.The third (and final) phase of the study involved production of 10 concrete mixtures to verify the incompatibility findings from the paste ...