A novel development of green ultra-high performance concrete (UHPC) based on appropriate application of recycled cementitious material

Qian, Diao; Yu, Rui; Shui, Zhonghe; Sun, Yu; Jiang, Chunyuan; Zhou, Fengjiao; Ding, Mengxi; Tong, Xuansheng; He, Yongjia

doi:10.1016/j.jclepro.2020.121231

Cited by 114 publications

(39 citation statements)

References 48 publications

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“…Some authors simply concentrated on a single treatment temperature [ 5 , 6 ] and others approached only a few properties, namely the fresh behavior and the mechanical strength [ 4 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Other studies were dedicated to the incorporation of varying percentages of RC in mortars and concrete [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Furthermore, results reported in the literature are contradictory, reflecting the lack of knowledge of these poorly explored new binders [ 1 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of the Treatment Temperature on the Microstructure and Hydration Behavior of Thermoactivated Recycled Cement

et al. 2020

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This paper intends to contribute to a better knowledge of the production and rehydration of thermoactivated recycled cement and its incorporation in cement-based materials. To this end, the influence of the treatment temperature on the properties of recycled cements and recycled cement pastes was assessed by means of a wide array of tests. Anhydrous recycled cement as well as the resulting pastes were characterized through density and particle size, water demand and setting time, thermogravimetry, X-ray diffraction, field emission gun scanning electron microscopy, isothermal calorimetry, 29Si nuclear magnetic resonance spectroscopy, flowability, mechanical strength, mercury intrusion porosimetry and scanning electron microscopy. The treatment temperature had a significant influence on the dehydration and hydration of recycled cement, essentially resulting in the formation of C2S polymorphs of varying reactivity, which led to pastes of different fresh and hardened behaviors. The high water demand and the pre-hydration of recycled cement resulted in high setting times and low compressive strengths. The highest mechanical strength was obtained for a treatment temperature of 650 °C.

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Section: Introductionmentioning

confidence: 99%

Influence of the Treatment Temperature on the Microstructure and Hydration Behavior of Thermoactivated Recycled Cement

et al. 2020

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“…Figure 4 displays the workability over time of 15P65. Contrary to what is usually observed in OPC mixtures, a quick workability reduction occurred during the first 15 min, due to the exothermic hydration of free CaO, as well as the RCP absorption [9,14,22]. This loss of workability is expected to increase with the incorporation percentage of RCP.…”

Section: Slump and Densitymentioning

confidence: 65%

“…The incorporation of RC in concrete has barely been studied, with only a few published papers [21,22]. Letelier et al [21] investigated the combined effect of the incorporation of recycled aggregates and RC in concrete, having incorporated 5-15% RC of varying fineness (75-300 µm) treated at different temperatures (400-900 • C).…”

Section: Introductionmentioning

confidence: 99%

“…Qian et al [22] conducted a study on the incorporation of RC treated at 650 • C in ultra-high performance concrete with a binder composed of lime powder (45.5%), silica fume (18.2%) and varying amounts of OPC and RC, for a w/b of about 0.2 and 3% of superplasticizer by weight of binder. The authors found that up to 25% OPC replacement with RC, the flowability decreased less significantly than for higher incorporation percentages, having attributed the workability reduction to the high surface area of the RC and CaO content.…”

Section: Introductionmentioning

confidence: 99%

“…The influence of RC incorporation on the volume stability of cement-based materials has barely been studied. Qian et al [22] investigated the autogenous shrinkage of the abovementioned high performance concrete, having found that the spontaneous shrinkage rate generally increased with the incorporation percentage of RC. This was attributed to the reduction of internal humidity of concrete due to the high surface area of RC, leading to self-drying and spontaneous contraction of concrete.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Characterisation and Shrinkage of Thermoactivated Recycled Cement Concrete

et al. 2021

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This paper investigates the mechanical and shrinkage behaviour of concrete with recycled cement (RC) thermoactivated from waste cement paste and waste concrete. Overall, compared to ordinary Portland cement (OPC), for the same water/binder ratio, the mechanical strength and ultrasonic pulse velocity were not significantly influenced by the incorporation of RC. The elasticity modulus decreased with the addition of RC and the shrinkage tended to increase at high RC content. The incorporation of up to 15% RC allowed the production of workable concrete with identical shrinkage and similar to higher mechanical strength than concrete with only OPC. RC proved to be a very promising more eco-efficient supplementary cementitious material.

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Improved forecasting of the compressive strength of ultra‐high‐performance concrete (UHPC) via the CatBoost model optimized with different algorithms

Katlav,

Ergen

2024

Structural Concrete

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This paper focuses on the applicability of CatBoost models constructed using various optimization techniques for improved forecasting the compressive strength of ultra‐high‐performance concrete (UHPC). Phasor particle swarm optimization (PPSO), dwarf mongoose optimization (DMO), and atom search optimization (ASO), which have been very popular recently, are preferred as optimization algorithms. A comprehensive and reliable data set is used to develop the CatBoost models, which include 785 test results with 15 input features. The performance of the CatBoost models (PPSO‐CatBoost, DMO‐CatBoost, and ASO‐CatBoost) optimized with different algorithms is thoroughly assessed by means of various statistical metrics and error analysis to determine the model with the best forecasting capability, and this model is compared with the models obtained from previous studies. In addition, Shapley additive exPlanations (SHAP) analysis is used to ensure the interpretability of the forecasting models and to overcome the “black box” problem of machine learning (ML) models. The obtained results demonstrate that all CatBoost models outstandingly forecast the compressive strength of UHPC. Among these models, the DMO‐CatBoost model stands out compared to the other models in various performance metrics, such as high coefficient of determination (R2) values, low root mean squared error (RMSE), mean absolute percentage error (MAPE), and mean absolute error (MAE) values, along with a smaller error ratio. In other words, the RMSE, R2, MAPE, and MAE values of the DMO‐CatBoost model for the training set are 3.67, 0.993, 0.019, and 2.35, respectively, whereas those for the test set are 6.15, 0.978, 0.038, and 4.51. Additionally, the performance ranking of the algorithms used to optimize the hyperparameters of the CatBoost model is as follows: DMO > PPSO > ASO. On the other hand, SHAP analysis showed that age, fiber dosage, and cement dosage significantly influence the compressive strength of UHPC. These findings can guide structural engineers in the design and optimization of UHPC, thus assisting them in developing strategies to improve the strength properties of the material. Finally, based on the best forecasting model developed in this work, a graphical user interface has been developed to easily forecast the compressive strength of UHPC in practical applications without additional tools or software.

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A novel development of green ultra-high performance concrete (UHPC) based on appropriate application of recycled cementitious material

Cited by 114 publications

References 48 publications

Influence of the Treatment Temperature on the Microstructure and Hydration Behavior of Thermoactivated Recycled Cement

Influence of the Treatment Temperature on the Microstructure and Hydration Behavior of Thermoactivated Recycled Cement

Mechanical Characterisation and Shrinkage of Thermoactivated Recycled Cement Concrete

Improved forecasting of the compressive strength of ultra‐high‐performance concrete (UHPC) via the CatBoost model optimized with different algorithms

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