Investigation of spray pattern in shotcrete applications

Ginouse, Nicolas; Jolin, Marc

doi:10.1016/j.conbuildmat.2015.05.061

Cited by 45 publications

(18 citation statements)

References 10 publications

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“…Apart from the pulsating concrete versus continuous accelerator flow, the binder-rich peripheral zone and the enrichment in coarse aggregates in the centre of the spray jet may create other inhomogeneities in the matrices. This effect was reported by Ginouse and Jolin [13,14], who observed the same pattern in the spray as in the receiving surface. Additionally, the rebound and the air trapped into the cement slurry can also lead to changes in the internal structure of the shotcrete and may cause macro and micro defects, as reported by Thomas [5].…”

Section: Influence Of Inhomogeneities/layerssupporting

confidence: 86%

“…The durability of all concretes is influenced by physical (porosity) and chemical (phase assemblage, pore solution) parameters. In the case of shotcrete, those parameters differ from conventional concrete due to several reasons: (1) the use of setting accelerators and special fast-setting binders leads to different hydrated phase assemblages and pore solution chemistry [8,9], and (2) the application method influences the porosity [10,11], the matrix homogeneity [12][13][14][15], and the binder to aggregate ratio [16][17][18]. The type of durability issue affecting shotcrete depends on the environmental surroundings [19].…”

Section: Introductionmentioning

confidence: 99%

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Durability of clinker reduced shotcrete: Ca2+ leaching, sintering, carbonation and chloride penetration

et al. 2021

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The reduction of clinker use is mandatory to lower the negative environmental impact of concrete. In shotcrete mixes, similarly to the case of conventional concrete, the use of supplementary cementitious materials (SCMs) and proper mix design allow for the substitution of clinker without compromising the mechanical properties. However, the impact of the substitution on the durability of shotcrete needs to be further assessed and understood. The results from the present study, obtained from real-scale sprayed concrete applications, show a reduction of the Ca2+ leaching and sintering potential of clinker-reduced shotcrete mixes due to the presence of SCMs. This positive effect, crucial for low maintenance costs of tunnels, is mainly related to a reduced portlandite content, which on the other hand negatively affects the carbonation resistance of shotcrete. Additionally, the hydration of SCMs positively influences the chloride penetration resistance presumably due to a combination of microstructural changes and changes in the chloride binding capacity. Differences found in the pore size distribution of the various mixes have low impact on the determined durability parameters, in particular compared to the effect of inhomogeneities produced during shotcrete application.

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Section: Influence Of Inhomogeneities/layerssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Durability of clinker reduced shotcrete: Ca2+ leaching, sintering, carbonation and chloride penetration

et al. 2021

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“…Tunnel shotcrete spraying is a process of spraying shotcrete at a very high speed onto a rock or concrete surface to prevent the collapse of the tunnel during excavation [2], [3]. To address the shortcomings of manual spraying such as a high rebound rate, large amount of dust, unstable construction quality, and slow construction progress [4], mobile concrete sprayer emerged. However, this method still requires an operator to manually operate the robot arm for spraying, which means that the quality of the shotcrete from this method depends largely on the experience of the operator.…”

Section: Introductionmentioning

confidence: 99%

Intelligent Detection for Tunnel Shotcrete Spray Using Deep Learning and LiDAR

et al. 2020

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Shotcrete spray is an indispensable process in tunnel construction. At present, the construction of tunnels in China is mainly depend on labor or mobile concrete sprayer, which has lots problems like timeconsuming, low precision, and labor intensive. An intelligent detection method for tunnel shotcrete spraying is proposed in this article. There are two main issues need to be solved, one is the modeling of tunnel in real-time to monitor the thickness of shotcrete and other is the detection of spraying area in the tunnel. The LiDAR can obtain a 3D model of tunnel after performing necessary preprocess on it in real-time. On the other hand, the spraying areas are usually divided by arches in the tunnel, so we can detect the position of arches to determine the spraying areas. Inspired by the YOLO algorithm, we proposed a novel neural network structure to detect the approximate bounding boxes of the arches and a line-detection algorithm is used to determine the final positions of the spraying area in the image. The size of the weight file of our neural network is only 2.57 MB after the use of some deep compression tricks, which means our model is device friendly. After that, the object detection results in the image will be projected to the point cloud data. The experimental results suggest that our method performed well in the detection for tunnel shotcrete spraying, and the mAP for spraying area detection was found to be 91.4%. INDEX TERMS 3D point cloud, deep learning, object detection, tunnel shotcrete.

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“…Currently, when it comes to shotcrete, a large amount of researches pay their attention on the pumpability and shootability of fresh concrete [11][12][13] or the mechanism of sprayed concrete [14,15]. Lianjun Chen et al [16] summarized the technologies for reducing cement dust during shotcrete from new process, new apparatus to new materials, as well as the pathological damage of cement dust.…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Research on Convergence Angle of Wet Sprayer Nozzle

Cheng

2018

CivileJournal

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Shotcrete is a popular support method in construction of both ground projects and underground projects, such as tunnels, subways, slopes and roadway, etc. However, at present researches on the influence of nozzle structure parameters on the performance of concrete injection are insufficient. This research focuses on the influence of various parameters of nozzle structure on the evenness and dust generating, and conducts a systematic study on the flow characteristics of the concrete in the nozzle of wet spraying machinery and the quality control law, through a comprehensive research method combining theoretical analysis, numerical simulation and field tests. On the basis of dynamic analysis of the internal flow field of the nozzle, the mathematical model and numerical model of the internal flow field of the nozzle are establishes. Then the simulation calculation of the flow field of the wet spray nozzle is conducted with the FLUENT® software. The fluid’s contour about velocity and phase volume fraction in the nozzle were obtained. On this basis this paper analyzed each phase’s volume fraction of the mixed fluid in the outlet section. The convergent section of the nozzle is tested in the spray concrete impact force distribution system. The results are in good correspondence with the results of theoretical analysis and numerical simulation, which verifies the validity and reliability of the conclusion of numerical simulation. This paper provides the basis for the optimization of nozzle structure, and the improvement of the sprayed concrete construction quality.

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Investigation of spray pattern in shotcrete applications

Cited by 45 publications

References 10 publications

Durability of clinker reduced shotcrete: Ca2+ leaching, sintering, carbonation and chloride penetration

Durability of clinker reduced shotcrete: Ca2+ leaching, sintering, carbonation and chloride penetration

Intelligent Detection for Tunnel Shotcrete Spray Using Deep Learning and LiDAR

Numerical and Experimental Research on Convergence Angle of Wet Sprayer Nozzle

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