Moisture Intrusion Research Articles

Housing Interventions and Control of Asthma-Related Indoor Biologic Agents

Subject matter experts systematically reviewed evidence on the effectiveness of housing interventions that affect health outcomes, primarily asthma, associated with exposure to moisture, mold, and allergens. Three of the 11 interventions reviewed had sufficient evidence for implementation: multifaceted, in-home, tailored interventions for reducing asthma morbidity; integrated pest management to reduce cockroach allergen; and combined elimination of moisture intrusion and leaks and removal of moldy items to reduce mold and respiratory symptoms. Four interventions needed more field evaluation, 1 needed formative research, and 3 either had no evidence of effectiveness or were ineffective. The 3 interventions with sufficient evidence all applied multiple, integrated strategies. This evidence review shows that selected interventions that improve housing conditions will reduce morbidity from asthma and respiratory allergies.

Time-Resolved Photoluminescence Spectra, Lifetime Distributions and Decay-Associated Spectra of Lanthanide's Exchanged Microporous–Mesoporous Materials

Time-resolved luminescence spectra of europium in parent and silylated microporous-mesoporous materials were analyzed by using the maximum entropy method and global multi-exponential fitting, providing lifetime distributions and decay-associated spectra. Silylation was used as a method for the hydrophobization of the materials surface in order to inhibit the moisture intrusion at the lanthanide's sites. Due to the well-known sensitivity of the europium photoluminescence properties to the local environment, our approach can simplify the description of the complex structure-photoluminescence relationships in terms of the individual europium species that contribute to the total emission of the system.

Moisture intrusion in viscoelastic porous media: Induced-stress and deformation

Porous media exposed to humid air absorb moisture which can lead to extensive internal damage and failure. In this paper, we analyze numerically the influence of the moisture intrusion in a two-layer viscoelastic porous media. The relationship between air humidity and moisture content inside the porous media was examined. It was also found that the local stress increases with the exposure time to humid air but decreases with initial moisture content of the porous medium. Furthermore, the stress components were tensile at the centre of the medium and compressive near the medium surface. The ultimate strength of the medium was only exceeded for the stresses in axial and tangential directions.

LEDs given a longer life

Researchers at Georgia Institute of Technology have developed an improved sealing process for organic light emitting diodes (OLED) to reduce moisture intrusion and improve device lifetime.

Forensic Engineering Investigation Of Moisture Intrusion Leading To Mold Conditions

While Moisture Intrusion Was Thought To Be The Reason For Floor Tile And Carpet Adhesion Failure In An Occupied Elementary School, The Flooring Problems Were Symptoms Of Only Some Of The Many Moisture Problems That Were Discovered. By Using Destructive And Non-Destructive Testing Methods, A List Of More Than A Dozen Construction Deficiencies Was Compiled. Since The School Was In Session, The Parent-Teacher Organization Was Kept Informed Of The Indoor Air Quality In The School. Indoor Air Quality Testing Was Performed At Strategic Intervals Of The Project And A Final Indoor Air Quality (Iaq) Test Was Performed At The Completion Of The Work As A Baseline For Recommended Future Testing.

Forensic Engineering Analysis Of Codes Causative Of Building Envelope Failures

Moisture Intrusion And Accumulation In The Building Envelope Causes Conditions Of Deterioration Including Development Of Mold Which Form The Basis Of Numerous Lawsuits. The Causes Of Intrusion Of Moisture/Water Into The Envelope Relate To Materials And Construction Methods Which In Turn May Relate To One Or Multiple Subcontractors Or Suppliers On A Project. Any Of The Contractors, Subcontractors, Suppliers Or Product Manufacturers May And Commonly Are Parties In Complex Litigations Involving Damage In The Building Envelope. The Involved Parties Commonly Include The General Contractor, Architect, Engineers, Masonry Subcontractors, Hvac Subcontractor, Window Manufacturer, Window Vendor, Framer/Window Installer, Roofer, Siding Subcontractor, Insulation Subcontractor Etc.

Performance Testing of Flashing Installation Methods for Brick Mold and Nonflanged Windows

Abstract One of the major sources of water intrusion in buildings is through openings in walls caused by windows and other fenestrations, in particular the interface between the window and wall. Numerous flashing products, including self-adhered products, have recently been developed to protect this window-wall interface from moisture intrusion. However, the proper installation of these flashing products is not well understood and installation methods are often misused. Various installation methods have been developed and tested to evaluate performance and ease of installation. While most of the flashing installation development has been focused on residential flanged-style windows, effective installation methods for wood framed “brick mold” windows as well as other “nonflanged” windows have not previously been developed and tested. A series of laboratory wall tests were used to compare the air leakage resistance (ASTM E 283), water leakage resistance (ASTM E 331), and durability (ASTM E 330) of various flashing materials and installation methods. The performance and durability of flashing as installed with round top windows, brick mold windows, and nonflanged windows were tested and evaluated.

Electrochemical impedance evaluation of aluminum/boron–epoxy composite bonds

Al/boron-epoxy double lap-shear specimens with five different surface preparations were exposed to hot, humid conditions for up to 3 years. Electrochemical impedance spectroscopy (EIS) measurements were taken using an in situ sensor throughout the exposure period. Periodically, some specimens were pulled to determine bond strength degradation. Aside from a set of deliberately poorly prepared specimens, all specimens retained at least 80% of their initial bond strength with the best specimens showing only a little degradation of strength. The low-frequency EIS impedance for measurements taken with sensor electrodes on the same composite surface decreased exponentially by two orders of magnitude during the exposures as the composite absorbed moisture. This decrease happens well before significant bond degradation, thus allowing the measurements to be used as a warning of moisture intrusion before the moisture has weakened the interface and resulted in a reduction of bond properties. One application of this bond health monitoring technology would be in bonded repair patches.

Interlayer and Design Considerations to Retard Reflective Cracking

To protect the structure and provide a new, smoother riding surface, many highway agencies overlay deteriorating portland cement concrete pavements with hot-mix asphalt (HMA) overlays. Reflective cracking through the overlays has been a persistent problem. Most methods that are used to delay the cracks have been based on tension (the horizontal movement occurring at the crack or joint interface). A performance-related flexural fatigue test addresses the tension, shear, and bending forces that result in reflective cracks. A reflective crack relief system consisting of an impermeable, highly elastic interlayer that uses fine-graded aggregates and a quality HMA overlay has been specified with flexural fatigue for crack resistance and Hveem stability for rutting resistance. Preliminary cracking data from several projects that used the specification and their control sections show that reflective cracking is delayed. Cores taken from the test sections show that even when the overlay cracks, the interlayer remains intact and impermeable, protecting the pavement structure from moisture intrusion. These cores also show that, unlike those in the control sections, the reflective cracks over the new system are offset from the underlying joints and further disrupt paths for water and giving better rideability. Seven state departments of transportation have used the performance-related specification for constructing the interlayer and overlay.

Forensic Investigation Of Moisture Intrusion Into Tilt-Wall Structures

The Author Was Retained By Attorneys Who Had Been Engaged By A Window Installer To Defend The Installer Against A Lawsuit For Damages To An Office Building, Which Had Been Damaged By Water Intrusion. Because The Facts Strongly Indicated That At Least Some (But Not All) Of The Windows Installed By The Client Did Indeed Leak, And Since It Was Reasonable To Believe That This Moisture Had Caused Some, But Not All Of The Damage To The Building, The Defense Strategy Devised Was As Follows: 1. Attempt To Quantify The Number Of Windows In The Building That Leak. 2. Attempt To Quantify All Other Sources Of Moisture Intrusion Into The Building. 3. Attempt To Quantify The Actual Cost Of The Damage Due To Water In The Building. 4. Attempt To Quantify The Cost To Eliminate The Sources Of Moisture To Repair The Building. 5. Devise A Rational Approach To The Apportionment Of These Costs Among The Sources Of Leaks Including Those Attributed To The Client. 6. Examine The Specific Causes Of The Window Leaks To Determine If They Are Due To Improper Installation, Poor Materials, Or Poor Design Since The Client Might Only Be Responsible For Improper Installation.

Using Fiber Optics to Detect Moisture Intrusion into a Landfill Cap Consisting of a Vegetative Soil Barrier

The intrusion of moisture into landfills can pose a health hazard because of the possibility that the moisture will carry harmful substances into the groundwater. Early detection of moisture anywhere within these landfills is essential if corrective action is to be taken well before an occurrence of this kind. This paper presents the results of a field-scale simulation test of the use of fiber optics to detect the presence of moisture within landfill covers, using a detection method based on the thermal response of soils as a function of their moisture content. By sending electrical current through an embedded stainless-steel tube, soils of varying moisture content were heated and time-dependent temperature measurements were obtained with a fiber-optic distributed temperature sensor system. The optical fiber itself lay within the tube, but its temperature was a function of how rapidly heat was conducted into the surrounding medium. The results of this experiment, which are in agreement with those obtained using more traditional “point” sampling and laboratory analysis, are presented along with the strengths and limitations of the thermal-response method of detecting moisture.

Forensic Engineering Report - A Moisture Litigious Hotel In Florida

The Forensic Engineer Was Directed To Seek The Cause Of A Plumbing Related Issue That Affected The Building Envelope. During The Investigation Multiple Causes Of Moisture Intrusion Into The Hotel Were Discovered. This Design Is Very Typical And Represents The Common Causes Of Failure Found In Many Hotels In Florida. The Control Of Moisture In Buildings In Hot And Humid Climates Is The Number One Complaint, And Source Of Litigation From Owners. The Design Professionals And The Contractor Must Understand Moisture Management And Control Strategies To Better Design And Build Buildings And Conditioning Systems. In Reality, The Real Issue Was An Hv Ac Design By A Northern Engineer For A Tropical Location.

Empirical Validation of a Gas Distribution System Moisture Drydown Model

Moisture is the most difficult impurity to remove from gas distribution systems due to its adsorption and desorption behavior. Several theoretical models have been proposed in an effort to understand moisture behavior and to predict the drydown time of gas distribution systems. We recently developed a model that takes into account the fluid dynamics of the bulk gas stream and incorporates two drydown regimes: a physisorbed regime and a chemisorbed regime. This paper compares experimental drydown data with model simulations of gas distribution systems under various configurations and conditions. The verified model can be applied as an engineering tool for designing a practical system and predicting the effects of a moisture intrusion into the system.

Tomahawk Nitrogen Pressurization Maintenance—Why?

ABSTRACTThis paper discusses the data that were recorded during a three‐month accelerated humidity test of two Tomahawk all‐up rounds (AURs), one pressurized with dry nitrogen in accordance with the current practice, and the other left unpressurized. Temperature and humidity were recorded inside the canisters and missiles. Data analysis consisted of psychrometric calculations to determine the moisture intrusion into these missiles during the test. The work was carried out in support of a technical effort directed at changing the storage and stowage environmental protection of the Tomahawk missile.

Bioaerosols: Prevalence and health effects in the indoor environment

Assessing the role of bioaerosols in residence-related symptoms involves (1) determining that symptoms are related to the residence by medical examination and careful questioning, (2) connecting reported symptoms with known or hypothesized effects of bioaerosols, (3) examining the residence for bioaerosol risk factors such as overcrowding/poor ventilation, inappropriate outdoor air intrusion, and dampness/standing water, (4) and finally, if no obvious risk factors are present, air sampling. Air sampling should always be a last resort and should use a reliable volumetric method. Particulate samplers, such as the Burkard personal spore trap, are inexpensive alternatives to viable particle samplers and will provide data on most organisms implicated in hypersensitivity diseases. Interpretation of residential bioaerosol sample data requires both qualitative and quantitative comparison with adjacent outdoor air and examination of aerosol changes related to domestic activities. Recommendations that should lead to a decrease in indoor bioaerosols include the use of air conditioning to allow limitation of outdoor aerosols, prevention of dampness or moisture intrusion, and discouraging the use of humidifying devices other than steam. Bioaerosol assessment in the workplace is often more complex than for residences. Because the symptomatic subjects are not in charge of the environment, such situations often lead to difficult employee/management relations and occasionally to litigation. It is essential that each step in workplace bioaerosol assessment be defensible and that the best possible methods are used. The approach is similar to the approach used for residences, but on a larger scale. Symptom assessment must include stress and ergonomic factors. Air sampling, if this is necessary, must usually be extensive with controls for ventilation rates, occupancy, and spatial variation.

A Model for the Diffusion of Moisture in Adhesive Joints. Part III: Numerical Simulations

Abstract The coupling mechanisms between the diffusion process and the viscoelastic response of an adhesive are explained. A numerical scheme for fully-coupled solutions is proposed and implemented in a two-dimensional finite element code. A number of numerical simulations are presented in order to illustrate the importance of the following features: (1) the bulk viscoelastic behavior, (2) penetrant size, (3) physical aging, (4) the strain dependence of the diffusion coefficient, (5) the concentration dependence of the diffusion coefficient and (6) differential, swelling. The effect of moisture intrusion on the stress (strain) distribution across a butt joint is also presented.

Experimental Analysis of Moisture Intrusion into the Al/Li-Polysulfone Interface

Abstract Aluminum-polymer bonds in hot-moist environments are subject to degradation due to moisture intrusion into the bonded joint and the resulting conversion of the surface oxide to the hydroxide. In order to analyze moisture intrusion, work has been done on diffusion and/or solubility characteristics of humid air or water in polymer materials. These investigations have been concerned with the actual solution and transport behavior of water in resins, especially the influence of morphology, temperature, or concentration, which affects the moisture absorption and desorption of homogeneous materials. However, such testing cannot give information on the effect of water at the substrate/adhesive interface but it can be used to screen water-sensitive adhesives.

Computational mechanical analysis of composite bondlines under environmental moisture loads

A combined moisture diffusion and mechanical computational analysis methodology was developed as part of an independent research program at Lockheed to enhance our understanding of nonlinear and coupled physical processes in materials. The physical behavior of interest is the mechanical response of composite material systems to environmental conditions which can change the materials' moisture content. In particular, it is desirable to know what set of environmental conditions will affect the integrity of a partial adhesive bondline when a bondline gap (no adhesive) is present. The Lockheed proprietary finite element analysis code DIAL was modified to analyze this phenomena in two stages. First, the temporal moisture partial pressures in the materials are calculated from initial and environmental boundary conditions and second, these partial pressures are then passed to a quasi-static mechanical analysis where the moisture data at each time step is treated as a dilatation (swelling) load. The resulting stress and strain state is then calculated, as well as gap closure, if any. Demonstration of this methodology was on a relatively simple 2-dimensional axisymmetric example problem. The results show primarily compressive stresses caused by the positive dilatation (swelling) induced by moisture intrusion of the structure. The stresses concentrate at adhesive bondlines, and bondline gap behavior (i.e., the absence of a contiguous adhesive bond at material interfaces) is correctly simulated. It should be noted that the behavior of the gap and any resultant stress/strains due to a change in moisture is problem dependent, and this example problem is meant as a demonstration of methodology.

Passive Surveillance: A Technique to Characterize the Condition of Power and Control Circuits in a Nuclear Plant

This paper reports on progress by EG&G Idaho in examination of electrical circuits exposed to the accident environment at Three Mile Island Unit 2 (TMI-2) during and after the loss-of-coolant accident of March 28, 1979. Interpretations of the data collected suggest that the major functional impact on the electrical circuits (a) occurs very late in time, (b) is caused by moisture intrusion, and (c) can be detected by remote surveillance prior to functional failure. The electrical testing was performed from outside the TMI-2 Reactor Building at the penetrations using a special circuit characterization and diagnostic system developed by EG&G Idaho. This paper concentrates on representative data from those circuits which were recently retested.

Adhesion and durability of metal-polymer bonds

A review is presented of those factors responsible for promoting the integrity and longterm durability of metal-polymer bonds used in the fabrication of aircraft and aerospace structures. Using a multidisciplinary approach and a variety of surface analytical techniques such as extended resolution scanning electron microscopy (XSEM), X-ray photo-electron spectroscopy (XPS), ellipsometry, and a new technique called surface behaviour diagrams (SBD), investigators at the author's laboratories have evolved several important concepts. First, it has been determined that the initial integrity of metal-polymer bonds depends critically upon the morphology of the surface oxide on the metal. For aluminium and titanium, the metals studied, it is demonstrated that certain etching or anodization pretreatment processes produce oxide films on the metal surfaces which, because of their porosity and microscopic roughness, mechanically interlock with the polymer forming much stronger bonds than if the surface were smooth. Second, the long-term durability of metal-polymer bonds is shown to depend strongly on the environmental stability (or lack of stability) of the same oxide which is responsible for good initial bond strength. For aluminium moisture intrusion at the bond line causes the oxide to convert to an hydroxide with an accompanying change in morphology and bond strength. For titanium the oxides appear to be much more stable than those on aluminium but under severe environmental conditions the oxide undergoes a polymorphic transformation which may lead to bond degradation. Third, it is observed that significant improvements in durability of adhesive bonds to aluminium can be achieved using an extremely simple treatment in which monolayer films of certain organic acids are applied to the adherend oxide to protect it against the effects of moisture.