Analysis of the Influence of Crystalline Admixtures at Early Age Performance of Cement-Based Mortar by Electrical Resistance Monitoring

Abstract

Crystalline admixtures are employed for waterproofing concrete. This type of admixtures can affect the early age performance of cement-based mixes. The electrical resistance properties of cement have been related to the initial setting time and to the hydration development. This paper proposes a system for remote monitoring of the initial setting time and the first days of the hardening of cement-based mortars to evaluate the effect of the incorporation of crystalline admixtures. The electrical resistance results have been confirmed by other characterization techniques such as thermogravimetric analysis and compressive strength measurements. From the electrical resistance monitoring it has been observed that the incorporation of crystalline admixtures causes a delay in the initial setting time and hydration processes. The measurements also allow to evaluate the influence of the amount of admixture used; thus, being very useful as a tool to define the optimum admixture dosage to be used.

Effect of a Crystalline Admixture on the Permeability Properties of Concrete and the Resistance to Corrosion of Embedded Steel

“…The corrosion behavior has been assessed through classical non-destructive electrochemical techniques. The same CA has been previously found to provide concrete with considerable resistance to water penetration under pressure [11] and to capillarity water absorption [24]. Although an air permeability test has been used before to assess the ability of concrete mixes (containing several additives including a commercial CA) to self-healing pre-cracked specimens [25], to the best of the authors' knowledge, no previous publication has studied the effect of an integral CA on the air permeability of bulk uncracked concrete.…”