Use of maturity method to estimate early age compressive strength of slab in cold weather

Tekle, Biruk Hailu; Al‐Deen, Safat; Anwar‐Us‐Saadat, Mohammad; Willans, Njoud; Zhang, Yixia; Lee, Chi King

doi:10.1002/suco.202000693

Cited by 10 publications

(6 citation statements)

References 21 publications

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“…It has been considered that the concrete will reach a strength of 2.5 MPa at a minimum age of two days. This value is considered safe according to several research studies that have dealt with the early age compression strength of concrete [20][21][22]. The strength of the concrete will then naturally increase over time, which implies that the safety factor will also increase over time.…”

Section: Theoretical Considerations On Mining Well Stabilitymentioning

confidence: 99%

Design and Implementation of Sampling Wells in Phosphate Mine Waste Rock Piles: Towards an Enhanced Composition Understanding and Sustainable Reclamation

El Ghorfi,

Inabi,

Amar

et al. 2024

Minerals

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Establishing a circular economy in mining begins with a dedicated sampling strategy as its fundamental phase. This specific approach is crucial for enhancing resource retrieval and isolating essential minerals from mining residues. By carefully examining and defining the makeup of waste materials, mining activities can discover overlooked possibilities, promoting sustainability. A thoughtfully planned sampling strategy not only reduces environmental harm but also sets the stage for the effective use of resources. In doing so, the mining industry can shift towards a circular model, adhering to the principles of waste reduction, material reuse, and ultimately promoting a more environmentally conscious and economically viable industry. In the phosphate industry and during the pre-concentration process of phosphate ore through screening, significant amounts of mining waste, consisting of various lithologies including indurated and fine phosphate, coarse-grained silicified phosphate, limestone, and marls, are deposited in waste rock stockpiles. Collecting representative samples from these heterogeneous materials presents challenges in accurately characterizing the entire stockpile. To overcome this issue, circular mining wells were implemented as a novel sampling method in waste rock stockpiles, enabling the collection of intact representative samples. This paper shares a successful experience in constructing three concrete-lined wells within a phosphate mine waste rock stockpile measuring 662 m in length, 240 m in width, and ranging in height from 0 to 65 m. The wells were dug at various depths, ranging from 20 m to 55 m, with a circular section and a diameter of 1.5 m. An integrated method utilizing analytical techniques in conjunction with numerical modeling via Robot Structural Analysis software (version of 2020) was utilized to assess the stress on the well supports and confirm their stability. This methodology serves as a valuable tool for evaluating the stability of similar wells, ensuring the safety of operators. The structural model yielded a stress level of 1 MPa, which aligned with the values obtained from the analytical model. Sensitivity analysis was performed on various parameters (friction angle, Poisson Ratio, and gravity), and the safety factor consistently remained above 1.5 for all scenarios investigated up to a depth of 60 m. Consequently, this study demonstrates that concrete-lined wells can be utilized safely for intact sampling in waste rock stockpiles. This sampling operation will allow the pursuit of optimizing resource utilization and enhancing environmental sustainability, by studying phosphate distribution in the Phosphate Mine Waste Rock (PMWR) for better recovery.

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Section: Theoretical Considerations On Mining Well Stabilitymentioning

confidence: 99%

Design and Implementation of Sampling Wells in Phosphate Mine Waste Rock Piles: Towards an Enhanced Composition Understanding and Sustainable Reclamation

El Ghorfi,

Inabi,

Amar

et al. 2024

Minerals

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“…The concrete matrix is a composite of various components, making it very difficult to accurately predict and measure the early age compressive strength [5,6]. Therefore, various direct and indirect methods have been developed to determine the compressive strength of concrete structures [4,[7][8][9]. Direct methods include core extraction from concrete structures for compressive strength measurements [10,11].…”

Section: Introductionmentioning

confidence: 99%

Study on Early Age Concrete’s Compressive Strengths in Unmanaged Curing Condition Using IoT-Based Maturity Monitoring

Kim,

Jung,

Kim

et al. 2024

Buildings

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Although accurately estimating the early age compressive strength of concrete is essential for the timely removal of formwork and the advancement of construction processes, it is challenging to estimate it in cool, cold, hot, or unmanaged conditions. Various nondestructive testing methods, including recent IoT-based techniques, have been proposed to determine the compressive strength of concrete. This study evaluates the maturity method using the wireless thermocouple sensor in assessing the early age compressive strength of concrete slabs, particularly those not subjected to watering and protection in a cool environment below 20 °C. For this purpose, wire and wireless thermocouple sensors were installed in reinforced concrete (RC) slabs, whereas wire thermocouple sensors were installed in concrete cylinders. In addition, the compressive strengths of standard-cured cylinders, field-cured cylinders, and core samples extracted from the RC slab were measured. On day 7, the maturity index (M) values for the field-cured cylinders were 7% lower than those of the standard-cured cylinders, and the M values for the RC slabs with wire and wireless sensors were 6% lower. The compressive strengths of the field-cured cylinders and core samples extracted from the RC slabs were 19% and 14% lower than those of the standard-cured cylinders, respectively. Thus, while the difference in M values was 6–7%, the difference in compressive strength was significantly higher, at 14–19%. In a cool environment without watering or protection, the difference in strength can be even greater. Consequently, a commercial IoT-based thermocouple sensor can replace conventional wire sensors and adopt to estimate early age compressive strength of concrete in unmanaged curing condition.

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“…Despite its widespread use, estimation of the time needed to obtain specific strength is challenging as it is influenced by various factors. Construction operations, such as removal of shoring systems, slipforming operations, and stressing of post-tensioned tendons, could potentially be optimised with an accurate assessment of the early-age concrete strength [2,[4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Monitoring the early-age concrete strength could be also used to determine the 28-day compressive strength and ensure concrete reaches its expected design strength.…”

Section: Introductionmentioning

confidence: 99%

Real-time monitoring of early-age compressive strength of concrete using an IoT-enabled monitoring system: an investigative study

Miller

Talebian

et al. 2023

Innov. Infrastruct. Solut.

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Determination of the early-age compressive strength of concrete is essential for quality assurance, safety, and economy of construction projects. Due to manual operation on construction site, conventional maturity meters are not efficient for live monitoring of the early-age concrete strength. Higher levels of automated and computerised improvements have been made possible by recent developments in wireless communications, sensor technologies, and data processing methods across the construction industry. For real-time monitoring of the early-stage concrete strength, the current study presents an innovative Internet of Things (IoT)-enabled system developed by concrete data sensors (CDS), an Australian-owned private business. The CDS sensor system (the system) communicates with temperature sensors via long-range wide-area network and is linked to a cloud-based platform for data storage. The suggested system’s effectiveness was assessed using three concrete mixtures and developed maturity relationships. It was observed that the predicted early-age compressive strength of the mixes matches well with the actual compressive strength and that the system can effectively automate the characterisation of maturity.

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Use of maturity method to estimate early age compressive strength of slab in cold weather

Cited by 10 publications

References 21 publications

Design and Implementation of Sampling Wells in Phosphate Mine Waste Rock Piles: Towards an Enhanced Composition Understanding and Sustainable Reclamation

Design and Implementation of Sampling Wells in Phosphate Mine Waste Rock Piles: Towards an Enhanced Composition Understanding and Sustainable Reclamation

Study on Early Age Concrete’s Compressive Strengths in Unmanaged Curing Condition Using IoT-Based Maturity Monitoring

Real-time monitoring of early-age compressive strength of concrete using an IoT-enabled monitoring system: an investigative study

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