The influence of the binder type & aggregate nature on the electrical resistivity of conventional concrete

Abstract

Concrete has been largely used in civil engineering due to its interesting fresh and hardened state properties. The 28-day compressive strength is the most important concrete property, being frequently used as an indicator of the material's quality. In this context, early-age mechanical properties (e.g., compressive strength) are becoming more critical nowadays to optimize construction scheduling. Several advanced techniques have been proposed in this regard and among those, electrical resistivity (ER) has been showing promising results. Yet, recent literature data have evidenced that ER might be significantly influenced by a variety of parameters such as the supplementary cementing materials (SCM) type/amount and aggregates nature used in the mix. These factors can hinder the practical benchmark of concrete mixtures proportioned with distinct raw materials. This work aims to appraise the influence of the coarse aggregate nature and binder replacement/amount on concrete ER and compressive strength prediction models through ER measurements using 24 mixtures manufactured with two different coarse aggregates natures (i.e., granite and limestone), two water-to-binder ratios (i.e., 0.6 and 0.4), and incorporating two different SCMs (i.e., slag, and fly-ash class F) with different replacement levels. Three distinct ER techniques (e.g., bulk, surface, and internal) and compressive strength tests were performed at different concrete ages (i.e., 3, 7, 14, and 28 days). Results indicated that the binder type and replacement amount significantly affect ER and compressive strength. The coarse aggregate nature presented minor influence for “ordinary” quality mixtures, while showing important impact on refined microstructure mixes. Finally, ER techniques, especially internal ER, were found to be quite reliable to predict the compressive strength of conventional concrete made of single, binary, and ternary binder blends. • The electrical resistivity (ER) setup highly influences the test outcomes. • The SCMs type and replacement amount significantly impacts on ER results. • The coarse aggregate nature does influence on the ER of low-quality mixtures. • The coarse aggregate nature affects ER of mixtures with refined microstructure.