Open-source EMM-ARM implementation for mortars based on single-board computer

Abstract

The EMM-ARM (Elastic Modulus Measurement through Ambient Response Method) allows the continuous monitoring of the elastic modulus of cementitious materials from early ages. The idea is to subject a beam, made of the specimen in its mould, to an excitation and monitor its response via an accelerometer. The excitation can either rely on naturally occurring vibrations, or on a controlled excitation system creating a signal with the necessary characteristics. The resonant frequency of the tested beam can be assessed with modal identification techniques, whereas the E-modulus of the tested material can be directly calculated with the dynamic equations of motion of the system. The original implementation of EMM-ARM uses specialized devices for the acquisition and excitation systems, which results in a relatively high price, as well as limited options for customization. The software used is based on proprietary systems (LabView), which further brings limitations on sharing for other institutions to use. On the other hand, one should bear into account that cyberphysical systems have shown significant evolutions in the last decade. Opensource platforms are increasingly popular and low-cost single-board computers are becoming widespread (e.g. Raspberry Pi). Electronic components have evolved parallel to these platforms, offering decent performances for low prices nowadays. The work hereby presented took inspiration from these cyber-physical systems to develop an open-source and cost-effective system able to conduct EMM-ARM tests independently from any other computing device. The system will be integrally presented as well as results obtained in comparison with the original implementation of the system.