The durability of cement-based construction materials depends on the environmental conditions during their service
life. A further factor is the microstructure of the cement bulk, established by formation of cement hydrates. The
development of the phases and microstructure under given conditions is responsible of the high strength of cementitious
materials. The investigation on the early hydration behavior of cements and cementing systems has been for a long time
a very important area of research: understanding the chemical reactions that lead to hardening is fundamental for the
prediction of performances and durability of the materials.
The production of 1 ton of Ordinary Portland Cement, OPC, releases into the atmosphere ~0.97 tons of CO2. This
implies that the overall CO2 emissions from the cement industry are 6% of all anthropogenic carbon dioxide. An
alternative to reduce the CO2 footprint consists on the development of eco-cements composed by less calcite demanding
phases, such as belite and ye'elimite. That is the case of Belite-Ye’elimite cements (BY). Since the reactivity of belite is
not quick enough, these materials develop low mechanical strengths at intermediate hydration ages. A possible solution
to this problem goes through the production of cements which jointly contain alite with the two previously mentioned
phases, named as Belite-Alite-Ye’elimite (BAY) cements. The reaction of alite and ye'elimite with water will develop
cements with high mechanical strengths at early ages, while belite will contribute to later values.
The final goal is to understand the hydration mechanisms of a variety of cementing systems (OPC, BAY and pure
phases) as a function of water content, superplasticizer additives and type and content of sulfate source. In order to do
so, in-situ laboratory humidity chambers with Molybdenum X-ray Powder diffraction are employed. In the first 2h of
hydration, reaction degree (α) of ye'elimite had been decreased for superplasticizer.
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