Comparison Between Different Experimental Techniques for Stiffness Monitoring of Cement Pastes

Abstract

In 2009, a new methodology for the continuous monitoring of E-modulus of cement-based materials since casting was proposed, under the designation EMM-ARM (E-modulus Measurement through Ambient Response Method). This methodology is a variant to classic resonant frequency methods that allows continuous stiffness monitoring from the instant of casting. After the encouraging results obtained in the first applications of EMM-ARM to cement pastes, the present paper gives continuity to previous developments, through validations with additional experimental methodologies and extension to thermal activation testing. At first, a comparison is performed between the results of EMM-ARM and those obtained through: pulse velocity methods (both ultrasonic contact probes and bender-extender elements), penetration resistance (Vicat needle) and cyclic compression on cylindrical specimens. Afterwards, the possibility of studying the activation energy of the stiffness evolution on tests conducted at 20ºC and 40ºC is explored.

Monitoring the early stiffness development in epoxy adhesives for structural strengthening

“…4). This clamping system, tested for the first time in the work performed by Granja et al [20], consisted of two steel parts fastened together with four screws and thus forming a central hole with a diameter equal to the outer diameter of the acrylic tube. It is noted that the clamping device itself was screwed to a heavy steel profile as to allow the consideration of perfect fixing of the cantilever.…”

Unloading‐Based Stiffness Characterisation of Cement Pastes During the Second, Third and Fourth Day After Production

“…The same method was used by Granja et al . who carried out comparisons with ultrasonics, with Vicat needle penetration testing and with unloading experiments on two different cement pastes with w / c = 0.50. These tests were carried out 2, 3 and 7 days after their production.…”

“…The latter relationship was reproduced by Fischer et al . based on a power law which suggests that creep will damage cement pastes at virtually any load level, even below 30% of the strength, which is typically used for cyclic loading–unloading experiments, see, e.g., . In order to protect cement paste samples from accumulation of damage, we here deliberately choose a specifically small compressive stress level.…”

Glycerol resulting from biodiesel production as an admixture for cement-based materials: an experimental study

“…The method relates the first resonant frequency of the composite beam to the evolving elasticity modulus of the tested specimen (Maia, Faria, & Figueiras, 2013) using the dynamic equation of motion of composite cantilever (Azenha et al, 2012a). Detailed information about specimen sizes and procedures can be found in detail elsewhere (Granja et al, 2014). The experiments with EMM-ARM took place in a climatic chamber at 20 ± 1°C.…”

“…The evolution of E-modulus of cement paste specimens was continuously followed from the instant of casting through EMM-ARM, which is a variant of classical resonant frequency methods for stiffness assessment (Azenha, Faria, Magalhães, Ramos, & Cunha, 2012a;Granja, Azenha, Sousa, & Ferreira, 2014). The cement paste to be tested is placed into an acrylic tube of known dimensions, stiffness and weight, which is in turn placed into a cantilevered support condition.…”