Innovative low-cost system for early age E-modulus monitoring of cement pastes : validation and application to nanosilica-added and limestone-calcined clay cements

The EMM-ARM (Elastic Modulus Measurement through Ambient Response Method) is an experimental technique that allows the determination of the E-modulus evolution curve of cementitious materials since casting. This work presents a validation of an innovative low-cost EMM-ARM test system and its use to study very early age (until 3 days) E-modulus evolution of cement pastes produced with a 1% nanosilica-added cement and a limestonecalcined clay (LC3 ) cement, produced with 1:2 claylimestone ratio and 50% clinker replacement. The tests produced, for the first time, continuous data about the early age E-modulus evolution, hydration degree and final setting time of these materials at the first 3 days of age. Compressive strength and Mercury Intrusion Porosimetry tests were also performed for complementary analysis. The validation results indicated the low-cost innovative system departed only up to 6.33% from reference results and had a coefficient of variation of the order of 4.50%. The application of the system on the studied cements revealed the nanosilica-added and LC3 cement pastes reached, respectively, 220% and 50% of an ordinary Portland cement (OPC) paste E-modulus at 12 h of age, and 180% and 70% at 24 h. The nanosilica-added and LC3 E-modulus gap to OPC paste progressively reduced after 3 days of age to 113% and 91%, respectively, tending to remain at this level at later ages