Abstract. This study aimed to evaluate the properties of concrete mixes produced mainly of hydrated lime and different types of Pozzolan. This mixture, which is nominated as PozzoLime, is presented as an alternative sustainable binder to replace Portland cement in concrete. The study tends to optimize the Pozzolan to lime proportions with respect to workability and strength of concrete. The investigated parameters are; water to binder ratio, aggregate to binder ratio and type of Pozzolan. The effects of these parameters on properties of the mixture in fresh and hardened states are studied. The included tests were; temperature profile, slump, fresh and ovendry density, compressive, splitting tensile and flexural strength and dynamic modulus of elasticity. Silicafume, Fly ash and Metakaolin were the used Pozzolan in this study .The temperature profile through hydration (coffee cup test) shows that all PozzoLime mixtures have significantly less environmental impacts (evolved heat) than Portland cement. The results also show that structural concrete with more than 28 MPa compressive strength at 28 days age can be produced by a binder consisted of 1:1 by weight ratio of Silicafume to hydrated lime, , and with a total binder content of 333 kg/m 3 .

This study represents a part of an extensive experimental program devoted to study the properties of different Lime-Pozzolan systems as a sustainable binder to replace Portland cement in concrete. These systems were Lime-Silica fume, Lime-Silica fume-Fly ash and Lime-Metakaolin. Four powder samples for X-ray diffraction, XRD, analysis was prepared from the studied systems. These samples were chosen to monitor the effect of curing age on the hydration process and to study the difference in hydration products when using different binder systems. According to the defined minerals by XRD analysis, the hydration products of all investigated Lime-Pozzolan mixtures are closely similar to those of Portland cements. The current XRD analyses have been employed to build recommendations for the forecast performance for each system.

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