Early Age Strength Enhancement

A New Robust Strength Enhancer Can Be Formulated With Existing Tec hnologies to Improve Many Performance Aspects of Cemen t. While the ultimate strength of concrete (or compressive strength at 28 days) is the main parameter for the design of concrete structures, it is the strength that the concrete achieves up to 24 hours after placement that will typically define the speed of the construction. [...]early age strength enhancement is a much sought-after performance parameter by both the cement and the concrete producers. In order to verify the impact of supplementary cementitious materials on the performance of the new additive, two OPCs were blended in a V-blender with 30 percent ground granulated blast furnace slag (GGBFS), 20 percent class F fly ash or 15 percent limestone (weight percent of OPC substitution), and EN-196 mortars were prepared to compare the early strengths in the presence and absence of 0.01 percent active HES (percent of cementitious weight). The absolute content of anhydrous cement phases (alite, belite, C3A, CAF) and of hydrated phases (calcium hydroxide and ettringite) can thus be determined to provide an insight on the impact of chemical additives on the cement hydration process. Optical microscopic observation of thin sections using polarized light allows the observation of the distribution, amounts and locations of some rel- evant cement phases, such as residual cement grains (alite, belite and ferrite), hydration or reaction rims, calcium silicate hydrate (C-S-H), ettringite and calcium hydroxide, as well as an indication of the cement paste porosity distribution.