PSI - Issue 64

M. Komary et al. / Procedia Structural Integrity 64 (2024) 1311–1317 Mahyad Komary/ Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction The monitoring of concrete structures in the early stages of curing and hardening is a critical component in ensuring their long-term structural integrity and durability. The early-stage monitoring of concrete can reveal essential information regarding its initial setting, strength development, and potential for early-age cracking, which are pivotal for predicting the lifespan and safety of civil structures [1]. Furthermore, the ability to detect and mitigate issues at this juncture can significantly reduce maintenance costs and extend the service life of infrastructure assets. Despite its importance, the widespread implementation of early-stage concrete monitoring faces substantial challenges, primarily due to the high costs and complexities associated with traditional monitoring technologies. Most existing solutions are either prohibitively expensive for widespread application or lack the precision and reliability needed for early detection of potential issues and above all of that they mainly require the presence of a technician for onsite measurements and lack the remote monitoring possibility. Table 1 summarizes the most common used technologies for early-stage monitoring of concrete and highlights that their high cost is the main reason for their limitations. This gap underscores a pressing need for innovative monitoring solutions that are both cost-effective and efficient in capturing critical early-stage data with the possibility of capturing data remotely and for long-term measurements applications. This research aims to explore the viability of a low-cost, Internet of Things (IoT)-based sensor for early-stage concrete monitoring. By leveraging the advancements in IoT technology and sensor development, this study proposes a novel approach to monitor the critical parameters of concrete in its early stages, such as temperature and humidity, which are indicative of its curing process and overall health. The objective is to demonstrate that a low-cost IoT-based sensor system can provide accurate, real-time data essential for ensuring the structural integrity and durability of concrete structures, thereby addressing the limitations of current methodologies and offering a practical solution for widespread monitoring needs.

Table 1. Comparative Analysis of Sensor Technologies for Early-Stage Concrete Monitoring. Technology Type Application Measured Parameters Notable Outcomes

Primary Limitation

Cost range ($)

Thermocouples

Temperature monitoring to assess heat of hydration Assessing setting time and early hydration processes Monitoring of concrete homogeneity and initial setting Surface monitoring for early crack detection

Temperature

Enables understanding of thermal profiles and potential for thermal cracking Can detect early-stage hydration characteristics and setting times Effective in assessing initial setting and early strength development

Costs associated with wiring and data acquisition systems

50 - 200

Electrical Impedance Spectroscopy (EIS) Ultrasonic Pulse Velocity (UPV)

Electrical Properties (Impedance)

High equipment cost and complexity of interpretation High cost of ultrasonic equipment and skilled operation required High cost for setup, including cameras and software

5,000 – 10,000

Pulse Velocity

2,000 – 10,000

Digital Image Correlation (DIC) Systems

Strain, Displacement

Non-contact method to detect surface cracks and deformations

10,000 – 20,000

2. Background Historically, concrete monitoring has been paramount in assessing the health and integrity of civil structures. Traditional methods, such as core sampling and ultrasonic pulse velocity tests, have provided valuable insights into the strength and condition of concrete. However, these methods are often invasive, labor-intensive, and not suitable for real-time monitoring. Recent advancements have seen the emergence of non-destructive techniques, including employing sensors as a part of Structural Health Monitoring (SHM) programs, which offer the potential for continuous monitoring without compromising the structure's integrity. Despite these advancements, challenges in cost, scalability, long-term durability and sensitivity especially for early-stage characterization of concrete remains.