High Performance Concrete and Drilled Shaft Construction

Brown, Dan; Schindler, A.

doi:10.1061/40902(221)31

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…It is reported that among 10,000 tested bored piles in the United States and Germany, more than 15% of pile test results showed signs of minor defect signs and 5% of tested piles were confirmed with major defects. [4][5][6] These defects can have significant financial implications and cause construction programme delays, as the evaluation of the pile bearing capacity, serviceability and structural safety is dependent on the knowledge of any existing pile anomalies. It is imperative that any construction defects are identified at an early stage, particularly when piles are heavily loaded.…”

Section: Introductionmentioning

confidence: 99%

Thermal integrity testing of cast in situ piles: An alternative interpretation approach

Sun

Elshafie

Barker

et al. 2020

Structural Health Monitoring

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Integrity testing of deep cast in situ concrete foundations is challenging due to the intrinsic nature of how these foundations are formed. Several integrity test methods have been developed and are well established, but each of these have strengths and weaknesses. A relatively recent integrity testing method is thermal integrity testing. The fundamental feature is the early age concrete release of heat during curing; anomalies such as voids, necking, bulging and/or soil intrusion inside the concrete body result in local temperature variations. Temperature sensors installed on the reinforcement cage collect detailed temperature data along the entire pile during concrete curing to allow empirical identification of these temperature variations. This article investigates a new approach to the interpretation of the temperature variations from thermal integrity testing of cast in situ concrete piles and presents a field case study of this approach. The approach uses the heat of hydration and heat transfer theory and employs numerical modelling using the finite element method. The finite element model can be customised for different concrete mixes and pile geometries. The predicted temperature profile from the numerical model is then compared, in a systematic manner, to the field test temperature data. Any temperature discrepancies indicate potential anomalies of the pile structure. The proposed new interpretation approach could potentially reduce construction costs and increase the anomaly detection accuracy compared to traditional interpretation methods.

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Section: Introductionmentioning

confidence: 99%

Thermal integrity testing of cast in situ piles: An alternative interpretation approach

Sun

Elshafie

Barker

et al. 2020

Structural Health Monitoring

View full text Add to dashboard Cite

show abstract

“…However, slump, soft soil, misplacement of rebar cage, and other multiple factors could cause defects when pouring the concrete (O'Neill, 1991). 15% of 5,000 to 10,000 tested concrete shafts had the indication of potential defects, and 5% of the tested shafts showed indisputable defect signals (Klingmüller and Kirsch, 2004;Brown and Schindler, 2007). Defects cannot be prevented during the construction completely since the excavation and concrete pouring are both blind processes.…”

Section: Introductionmentioning

confidence: 99%

Influence of Aggregates in Concrete on Fiber-Optic Based Thermal Integrity Profiling Analysis of Concrete Structures

Zhong

Deng

2020

Front. Mater.

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Fiber-optic sensor has drawn wide attention in the non-destructive testing and evaluation of civil engineering materials due to its high accuracy and resolution as well as cost-efficiency. Currently, using optical fiber as the temperature sensor is proposed to conduct the thermal integrity profiling (TIP) of concrete structures. However, concrete is not a thermally homogeneous material as assumed in current studies of concrete TIP. Its essential components, such as aggregates may cause thermal inhomogeneity problems when implementing fiber-optic sensors for TIP. In this paper, we use the concrete structures with different grades of aggregates to conduct numerical simulation for non-destructive thermal testing. The goal is to investigate how the thermal inhomogeneity caused by aggregates would influence the testing result. Firstly, we establish three concrete structure models with three different grades of aggregates based on the scenarios where these concrete structures will be used. Then, we numerically simulate the thermal process on these models and extract the temperature at the location where optical fiber would be installed. The influence caused by the inhomogeneity of aggregate size and distribution as well as the possible method to minimize the effect are evaluated in the paper. Overall, aggregates of concrete have a significant influence on the accuracy of TIP analysis, and defects could be veiled if no proper treatment to the data is implemented for TIP analysis.

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“…e existence of defects within the concrete shaft is mainly due to some problems of construction and design deficiencies [1]. Among 5,000 to 10,000 shafts tested, 15% of shafts showed the deviation from ideal signal and 5% of tested shafts showed indisputable defect indication [2,3]. Since both excavation and concreting are blind processes when building drilled shafts, it is impossible to completely prevent defects from happening during construction.…”

Section: Introductionmentioning

confidence: 99%

Optical‐Fiber‐Based Smart Concrete Thermal Integrity Profiling: An Example of Concrete Shaft

Zhong

Guo

Deng

2018

Advances in Materials Science and Engineering

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Concrete is currently the most widely used construction material in the world. The integrity of concrete during the pouring process could greatly affect its engineering performance. Taking advantage of heat production during the concrete curing process, we propose an optical-fiber-based thermal integrity profiling (TIP) method which can provide a comprehensive and accurate evaluation of the integrity of concrete immediately after its pouring. In this paper, we use concrete shaft as an example to conduct TIP by using the optical fiber as a temperature sensor which can obtain high spatial resolution temperature data. Our method is compared with current thermal infrared probe or embedded thermal sensor-based TIP for the concrete shaft. This innovation makes it possible to detect defects inside of the concrete shaft with thorough details, including size and location. First, we establish a 3D shaft model to simulate temperature distribution of concrete shaft. Then, we extract temperature distribution data at the location where the optical fiber would be installed. Based on the temperature distribution data, we reconstruct a 3D model of the concrete shaft. Evaluation of the concrete integrity and the existence of the potential defect are shown in the paper. Overall, the optical-fiber-based TIP method shows a better determination of defect location and size.

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High Performance Concrete and Drilled Shaft Construction

Cited by 5 publications

References 4 publications

Thermal integrity testing of cast in situ piles: An alternative interpretation approach

Thermal integrity testing of cast in situ piles: An alternative interpretation approach

Influence of Aggregates in Concrete on Fiber-Optic Based Thermal Integrity Profiling Analysis of Concrete Structures

Optical‐Fiber‐Based Smart Concrete Thermal Integrity Profiling: An Example of Concrete Shaft

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