Institute for Transportation

About the research

This study investigated alternative mixture design strategies for ultra-high performance concrete (UHPC) incorporating different types of supplementary cementitious materials (SCMs) and different types, sizes, and dosages of superabsorbent polymers (SAPs). In the first stage of this investigation, the effects of natural zeolite on the hydration development of UHPC were studied. UHPC mixtures were prepared in which silica fume, the most common SCM currently used in UHPC, was gradually replaced with natural zeolite in 25% increments. The hydration development of the mixtures was evaluated through several macroscale and microscale experiments. It was found that zeolite particles are capable of internally curing the surrounding unhydrated cement particles through water desorption over time. Furthermore, when used together, silica fume and zeolite exhibited a synergistic effect that further enhanced the degree of hydration (DOH) of the cement particles. In the second stage, the hydration development of mixtures containing different SCMs, including silica fume, silica fume and zeolite, zeolite, and limestone, were compared with those of a control mixture. A similar experimental program to that pursued in the first stage was completed. In the third stage, an alternative approach to increasing the hydration of cement particles in UHPC using SAPs was evaluated through the preparation of multiple mixtures with various SAP types, sizes, and dosages. Employing a holistic testing matrix, it was observed that the introduction of SAPs to the UHPC mixtures increased the DOH of the cement particles and improved the dimensional stability of the developed mixtures. The results of this study provided a fundamental understanding of the behavior of each SCM and SAP type in UHPC individually and in combination with each other. The outcomes can be employed to select the most appropriate SCMs and SAPs based on a given project’s needs and target applications.