Low Carbon Concrete Admixtures. A New Class of Products for Concrete Net Zero 2050 Scenario

Among the main actions to a net concrete zero future, saving in cement and binders by replacement of clinker with supplementary cementitious materials (SCMs) is considered a major task. Nevertheless, it is well known that SCMs react slower compared to clinker and can negatively affect the strength development, both at early and long curing times. Moreover, clinker itself never hydrates completely and residual unreacted fractions always remain in concrete. Under such premises, the expected reduction of the clinker-to-cement ratio from the actual value of 0.71 to the target value of 0.57 by 2050 might be hardly achievable. Low Carbon Concrete Admixtures (LCCAs) is a new class of admixtures that comes alongside the existing water reducers, retarders and accelerators and it is destined to take on a prominent role as an essential integration for the sustainability of concrete. LCCAs increase the degree of hydration (DoH) of cements and compensate the decline of both early and final strength of blended cements compared to Portland cements, assuring a more rationale use of cement. LCCAs permit to achieve the same compressive strength with reduced dosage of cement. Moreover, by using LCCAs it is possible to increase the fraction of SCMs in blended cements and in concrete without detrimental effects on compressive strength. In the present work, an introduction to the new class of LCCAs is presented with examples how they can effectively play a fundamental role to reduce the carbon foot-printing of concrete in the view of the Net Zero 2050 Scenario.