## 1 Introduction  
Compaction is the most critical aspect of earthwork in civil engineering projects, such as the construction of pavements, embankments, railways, factories, stadiums, and the housing sector. It improves the physical and dynamic properties of earthen materials by enhancing the strength and bearing capacity, controlling excessive subsidence and undesirable volume change, and reducing permeability. Quality Control (QC) and Quality Assurance (QA) methods ensure the compaction quality according to the design specifications. The objective of QA/QC is to improve the quality of the compaction, stability, and infrastructure service level. A widely accepted QA/QC criterion for compaction is uniformity and desired density based on in situ measurements. In situ measurements are also a common problem in other industry fields for quality assurance and control; for example, in the air emissions control of heavy metals from power plants, specific rigorous models have to be developed to measure unfeasible measurements to improve the operative management [1]. Similarly, in compaction, the conventional QA/QC methods rely on on-site manual measurements and post-compaction tests at limited spots [2]. These methods have several shortcomings: (1) the test results are based on limited point samples not representing the compaction quality of the entire work area; (2) these tests are time-consuming, labor-intensive, and have poor control accuracy; (3) the on-site destructive manual test cannot provide real-time compaction information; (4) the number of roller passes are based on operator judgment,which could produce under- or over-compaction zones. These inherent limitations lead to unreliable testing results and misleading compaction information, which may cause long-term performance failure and high infrastructure maintenance costs [3,4]. The advancement in information and sensing technologies has transformed every sector of life, providing modern and efficient solutions [5]. In recent years, industry 4.0 and cloud computing have been key for providing solutions for process monitoring, system optimization, and performance assessment with appropriate data collection strategies and cloud storage systems [6]. These technologies have also revolutionized the construction industry and offer innovative solutions to improve productivity, efficiency, quality, and control throughout the project life cycle [7, 8, 9]. An emerging and constantly evolving technology named Intelligent Compaction (IC) has the potential to address conventional compaction problems [3,10]. IC technology was first introduced in the 1970s and is still under continuous development [11]. It consists of a high-precision accelerometer vibratory roller, a Global Positioning System (GPS), an infrared thermometer, and a real-time feedback system [12]. Figure 1 shows the generic structure of the IC roller. The accelerometer monitors the vibration characteristics of the roller drum to measure the compaction strength during operation. The precise GPS provides the location of the roller, and the infrared thermometer measures the on-surface temperature. The real-time feedback system reports compaction information on the onboard computer screen. The IC roller provides spatially referenced compaction information in real time with 100% coverage of the compacted area [13]. The compaction information includes the roller speed, location, number of passes, vibration amplitude and frequency of drum, and Compaction Meter Value (CMV). CMV is a unitless value that characterizes the compaction quality and provides Continuous Compaction Control (CCC) in real time [14,15]. CMV calculation is based on the dynamic response between the vibratory drum and the material under compaction, indicating material stiffness. The higher the CMV values, the larger the stiffness, and vice versa. Following several years of IC technology in use, the Federal Highway Administration (FHWA) of the United States Department of Transportation (USDOT) started research on the IC roller in the year 2000.