Polyisobutylene and Silicone in Warm Edge Glazing Systems—Evaluation of Long-Term Performance

This article describes the characteristics of one type of sealing system used in warm edge glazing units and analyses the possible causes of damage. Attention was focused on the performance of the dual seal, PIB/silicone system. This type of glazing is widely used for modern curtain walls and roofs of office buildings and shopping centres. Study was focused on PIB displacement defects, which affects both the appearance and thermal performance of the curtain wall system. Wide-ranging field surveys were conducted to examine the problems identified in some office buildings. The information gathered in this way was used to identify the critical areas and causes of seal displacement in the analysed insulating glass units (IGUs). Laboratory tests were conducted on PIB and silicone seals retrieved from the removed defective units. The properties of these materials were determined and used to evaluate the applied edge sealing system and build a representative numerical model. Due to the problems encountered in deriving accurate analytical formulas, finite element (FE) approximation was used as a problem solving tool. The generated FE model and strain analysis were the key parts to obtaining a true representation of the actual behaviour of IGUs subjected to various environmental loads, taking into account the influence of the air cavity. Results of computer simulations and laboratory tests were compared for model validation. The effect of changes in ambient pressure was examined, showing the development of tensile strains in the silicone and PIB, which can lead to debonding. The greatest principal strains occur at the silicone/butyl rubber interface and this location should be considered to be the most susceptible to failure. The observations are summarised in the final conclusions. Additionally, as field study showed, after ten years in service, the percentage of damaged units is considerable. More frequent IGUs inspection should cover both appearance and thermal imaging to detect unsealed panels. From the standpoint of both durability and appearance, dual silicone/PIB should be phased out in favour of modern seal systems.

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Optimized Spacing Of The Longitudinal Reinforcement In CRCP To Avoid Horizontal Cracking

10.33593/qwd967ng ◽

2021 ◽

Author(s):

Muhammad Kashif ◽

Pieter De Winne ◽

Muhammad Wisal Khattak ◽

Amelie Outtier ◽

Hans De Backer

Keyword(s):

Outer Region ◽

Maintenance Cost ◽

Fe Model ◽

Longitudinal Reinforcement ◽

Transverse Cracks ◽

Field Investigations ◽

Contraction Joints ◽

Long Term Performance ◽

Term Performance

Continuously reinforced concrete pavement (CRCP) is characterized by the absence of transverse contraction joints and the presence of longitudinal and transverse reinforcement. The continuous longitudinal reinforcement holds the transverse cracks, caused by the longitudinal shrinkage of concrete, tightly together and thus provides long term performance with minimal maintenance cost. Field investigations on recently constructed CRCP's in Flanders region of Belgium indicated horizontal cracking in the vicinity of the longitudinal reinforcement under the transverse cracks which eventually causes the punch-out distress at the edge of the pavement slab. This paper shows the results of a finite element (FE) study to investigate the effect of varying longitudinal reinforcement on the risk of horizontal cracking in CRCP under typical Flanders conditions. For this purpose, a (3D) FE model of CRCP is developed using a FE package Diana 10.2. The varying longitudinal reinforcement with a most narrow spacing of 125mm in the outer region of the pavement slab is applied while keeping the same CRCP reinforcement ratio. A comparison is made with the conventional longitudinal reinforcement spacing (170mm). Development of concrete stress in the vicinity of the longitudinal reinforcement is plotted against the different longitudinal steel spacing. Findings show that the stress in concrete near longitudinal reinforcement is significantly reduced up to maximum 17% when the narrow spacing is used. In addition, the steel stress in the longitudinal reinforcing is reduced up to maximum 31.75% in the outer region of the pavement slab.

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Long Term Performance of Fusion Bond Epoxy Coated Pipelines

2004 International Pipeline Conference, Volumes 1, 2, and 3 ◽

10.1115/ipc2004-0570 ◽

2004 ◽

Author(s):

Robert Worthingham ◽

Matt Cetiner

Keyword(s):

Service Life ◽

Cathodic Protection ◽

Laboratory Tests ◽

Large Diameter ◽

Service Temperature ◽

Line Pipe ◽

Coating Type ◽

Long Term Performance ◽

Term Performance

TransCanada Pipelines has been using fusion bond epoxy (FBE) external coatings for large diameter line pipe since the early 1980’s. Overall, this coating type, when applied in accordance to the CSA Z245.20 standard provides excellent protection and long term service life. However, some reports from the field described the periodic occurrence of blistering and disbondment of the coating. In order to understand the magnitude and causes of these phenomena, an investigative program was initiated. Laboratory tests and a program of field examinations were carried out. Some of the variables considered were: age of the coating; service temperature; cathodic protection (CP) levels; and soil type. No evidence of a pipeline integrity threat associated with fusion bond epoxy deterioration was found at any of the locations examined. Observations and correlations of coating to exposure conditions will be presented.

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The Use of Laboratory-Measured and Strain-Gauge Backcalculated Asphalt Stiffness for Rutting Performance Prediction

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198119825644 ◽

2019 ◽

Vol 2673 (3) ◽

pp. 323-333

Author(s):

Erdem Coleri ◽

John T. Harvey

Keyword(s):

Performance Prediction ◽

Strain Gauge ◽

Asphalt Concrete ◽

Laboratory Tests ◽

Concrete Materials ◽

Long Term Performance ◽

Term Performance ◽

The Impact

Laboratory tests are conducted with asphalt concrete materials to determine the expected in-situ performance. In addition, laboratory test results are commonly used in mechanistic-empirical design methods for material characterization to improve the predictive accuracy of the models. However, the effectiveness of laboratory tests in characterizing the long-term performance of asphalt concrete materials needs to be validated to be able to use the results for pavement design and long-term performance prediction. Inaccurate performance characterization and prediction can directly affect the decision-making process for pavement maintenance, rehabilitation, and reconstruction and result in unexpected early failures in the field. The major objective of this study is to determine the impact of using laboratory-measured asphalt stiffness on the prediction accuracy of mechanistic-empirical models. In addition, the effect of using linear-elastic modeling assumptions (layered elastic theory) and neglecting the nonlinearity of pavement response at high load levels (and/or at high strain levels for weaker structures) on the predicted rutting performance was determined. In this study, the effectiveness of the use of laboratory asphalt stiffness tests for in-situ asphalt stiffness characterization was determined by comparing the rutting performance predicted using laboratory-measured stiffness to rutting predicted using strain-gauge backcalculated stiffness. It was determined that laboratory tests are able to characterize the in-situ stiffness characteristics of the asphalt mix used in this study and the stiffness characterization process suggested in this study can provide reliable rutting performance predictions. Results of this study are only applicable to tested rubberized asphalt concrete mixtures.

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Forensic laboratory tests to evaluate long-term performance of reclaimed asphalt pavements: Connecticut case study

Road Materials and Pavement Design ◽

10.1080/14680629.2016.1266767 ◽

2016 ◽

Vol 18 (sup1) ◽

pp. 311-335 ◽

Cited By ~ 1

Author(s):

Iliya Yut ◽

James Mahoney ◽

Anne-Marie McDonnel

Keyword(s):

Laboratory Tests ◽

Asphalt Pavements ◽

Reclaimed Asphalt ◽

Long Term Performance ◽

Term Performance ◽

Reclaimed Asphalt Pavements

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Applicatons of Hydration Thermodynamics to In-Situ Test Results

MRS Proceedings ◽

10.1557/proc-333-145 ◽

1993 ◽

Vol 333 ◽

Cited By ~ 1

Author(s):

M. J. Plodinec ◽

G. G. Wicks

Keyword(s):

Laboratory Tests ◽

Glass Production ◽

Natural Environments ◽

Test Results ◽

In Situ Tests ◽

Important Conclusion ◽

In Situ Test ◽

Long Term Performance ◽

Term Performance

ABSTRACTAn extremely important question for the eventual disposal of glass in natural environments is the relevance of laboratory testing of glass durability to the long-term performance of glass in geologic environments. The purpose of this study was to attempt to provide an empirical answer to that question, by applying the hydration thermodynamics approach (which has successfully been applied to laboratory tests of glass durability) to the results of longer-term testing in natural environments.The results show that hydration thermodynamics is a useful tool for explaining the effects of glass composition observed in in-situ tests, in several environments. Thus, it appears to provide a link between laboratory tests of glass durability and the results of in-situ tests in natural environments. Perhaps the most important conclusion of this effort is that the in-situ test results emphasize the importance of control of chemical composition during glass production as a means of achieving a durable glass.

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