## 1 Introduction  
Concrete is widely used in the construction industry. The material requires sufficient strength and durability to be used in building construction for different types of structural members, such as foundations, beams, walls, slabs, or columns. During the concrete's placement, it is important to monitor its status throughout the entire concrete formwork process, until the material cures. The formwork must remain in place to support a concrete structure during the construction. This process must consider factors such as the class of concrete, cement type or grade, humidity, temperature, and size/type of the structural components [1; 2; 3]. The formwork removal time is critical to the concrete gaining sufficient strength, as well as to the cost and time management of the entire construction project; this is because early removal leads to rework, which leads to project delays [4; 5]. The current state of practice has established a standard time to remove concrete formworks during a construction project [6; 7; 8]. Tailored time determination involves employing a concrete maturity method that estimates the mechanical properties of the concrete, based on the temperature during curing concrete [9; 10]. This approach involves monitoring the concrete's temperature and using the data acquired to estimate its strength and the time needed for the formwork [11]. To monitor the temperature and strength of concrete, the current state of practice uses a mobile-based or wireless sensor-embedded monitoring system [9; 12; 13]. Such studies have focused only on the schematic design for monitoring and collecting sensor data. The concrete formwork is placed for all concrete structural elements such as columns, walls, and slabs. Therefore, sensor data regarding the concrete's maturity obtained from different elements can be stored and managed in the building information modeling (BIM) environment because BIM can store geometric and semantic information of the construction project. Previous systems have focused only on collecting data and monitoring the condition of the concrete, and not providing real-time information about the appropriate time to remove the formwork. To address this concern, the present research expanded BIM's interoperability to monitor concrete's maturity and determine the formwork removal time by using wireless sensor data. BIM is capable of integrating all stages of construction into a single digital model, achieving high-quality construction, accurate performance and cost estimates, and continuous monitoring and control, as well as maintaining an up-to-date information source that facilitates project stakeholders achieving a clear overview of the project for use in informed decision-making [14; 15]. This study incorporates BIM and a sensor-based concrete maturity method to monitor and manage data related to various concrete-based structural components (e.g., slabs, walls, columns) and their strengths. This research used a module and wireless sensors embedded in fresh concrete, measured the concrete's temperature, and then automatically calculated its maturity so that its strength would be predictable. To expand BIM's interoperability, a BIM application programming interface (API) was applied that can transfer data related to the concrete's maturity to the BIM environment from sensors in real-time. All information about the temperature and maturity of the concrete can be monitored through planted sensors to the BIM environment, and stored in an industry foundation class (IFC) format. To test the interoperability, this research conducted a field case study in a building construction project in Iran. The results showed that BIM was able to interoperate with the data collected from the sensors, receive data related to the concrete's maturity, and calculate the appropriate concrete formwork removal time. The time to remove the formwork was less than what would have resulted from using the standardized regulation alone, and still clearly ensured the necessary level of strength.