Towards a robust and versatile method for monitoring E‐modulus of concrete since casting: Enhancements and extensions of EMM‐ARM

Abstract

In face of the importance of assessing mechanical properties of cement‐based materials since early ages, as well as the known limitations of existing methods, the EMM‐ARM (Elasticity Modulus Measurement through Ambient Response Method) was initially proposed in 2009. Since its first application, this method has been under constant development and extension to the study of other materials such as stabilized soils or epoxy resins. Extensive use has revealed several limitations on robustness and versatility that are addressed through a set of improvements proposed in this paper. Such improvements attempt to make EMM‐ARM more appropriate for systematic applications both in laboratory and in situ environments. These objectives were achieved through the application of a new test mould material, redesigned support systems, and the development of a new reusable mould. Additionally, the use of a small excitation applied to the beam to decrease the sensitivity of the method to the environmental noise was assessed.

Stiffness evolution of natural hydraulic lime mortars at early ages measured through EMM-ARM

“…The EMM-ARM is a methodology proposed by Azenha et al [5] for cement-based materials. It has been widely validated for cement pastes [7,[21][22][23], cement mortars [7], concrete [5,24] and recently for aerial lime-cement mortars [25]. In this paper, it was applied for the first time to the study of NHL mortars.…”

Mechanical properties of lime–cement masonry mortars in their early ages

“…Elasticity Modulus Measurement through Ambient Response Method) is a method, which was introduced in 2009 by Azenha[30], to measure the development of stiffness of cement pastes and concrete. With regard to mortars, and taking into account the most recent developments of the method[37], a PVC mould was used, filled with the mortar to be tested. The mould was placed horizontally in simply supported conditions and subjected to forced vibrations at mid-span.…”

“…Subsequently, evolution of the first flexural resonant frequency of the composite mould was assessed, as a result of the increasing stiffness of mortar cast inside it. Continuous estimations of Young's modulus were obtained employing the dynamic equation of motion, according to the principles set forward in[37,38]. This method was used for all mortar mixes, to study the evolution of Young's modulus from the time of casting up to the age of day 7, with curing temperature of 20±2°C.…”

Characterization of Non-proprietary UHPC for Use in Rehabilitation/Strengthening Applications

“…The final setting time, determined according to the standard EN 196-3, was considered as "time-zero" for the autogenous shrinkage evaluation. The Elasticity Modulus Measurement based on Ambient Response Method (EMM-ARM) [4] was used to continuously monitor the E-modulus evolution of UHPC since casting. The EMM-ARM is based on the identification of the resonant frequency of the testing mould (plastic hollow cylinder in simply supported conditions, filled with the sample to be tested immediately after mixing), which evolves along time due to the progress of hydration reactions.…”