scholarly journals Analysis of causes of the end of service life of a spray polyurethane foam and polyurea roof

2020 ◽  
Vol 172 ◽  
pp. 15002
Author(s):  
Targo Kalamees ◽  
Simo Ilomets ◽  
Mattias Põldaru ◽  
Paul Klõseiko ◽  
Urve Kallavus ◽  
...  
Keyword(s):  
Service Life ◽  
Polyurethane Foam ◽  
Field Measurements ◽  
High Water ◽  
Climatic Conditions ◽  
Water Vapour Pressure ◽  
Hygrothermal Performance ◽  
Durability Prediction ◽  
Humidity Measurements ◽  
Term Performance

Spray polyurethane foam (SPF) roofs are widely used in North America. Much fewer usage examples and experience can be found in Northern European cold climatic conditions. This study analyses hygrothermal performance and the reasons for the roof’s degradation and end of service life of an SPF and polyurea roof. The service life of the roof is over and major reconstruction is needed eight year after construction. The current study uses field measurements included onsite temperature and humidity measurements and extensive surveying, the roof was opened from several locations and test samples were taken for laboratory tests. The influence of UV radiation on the loss of adhesion was tested. Solar radiation quickly degraded the top surface of the in-situ sprayed polyurethane foam insulation causing a weak connection between the foam layers. Due to mechanically damaged and UV degraded polyurea roofing, water has leaked into the SPF. The water inside or below the foam evaporated during sunny days and broke the adhesion of different foam layers. Larger foam blisters were observed on the upper part of the insulation caused by high water vapour pressure. This is considered the most realistic cause of separation of the SPF layers. The analyse of hygrothermal performance, service life, and durability prediction should be included into the design process, especially for structures with small or without long term performance experience.

Effect of Zeolite Admixture on Freeze/Thaw Resistance of Concrete Exposed to the Dynamic Climatic Conditions

2014 ◽  
Vol 982 ◽  
pp. 27-31 ◽  
Author(s):  
Václav Kočí ◽  
Miloš Jerman ◽  
Jiří Maděra ◽  
Robert Černý
Keyword(s):  
Service Life ◽  
Computational Simulation ◽  
Climatic Conditions ◽  
Building Envelope ◽  
Point Of View ◽  
Freeze Thaw ◽  
Hygrothermal Behavior ◽  
Hygrothermal Performance ◽  
Concrete Building ◽  
Positive Effect

This paper aims at computational simulation of effect of zeolite admixture on service life of concrete building envelope from point of view of freeze/thaw resistance. Hygrothermal behavior of two types of concrete is studied in this paper: reference concrete without any admixtures and zeolite concrete with 40 % zeolite as cement replacement. The computations are performed using computer simulation tool HEMOT, which processes the input parameters using finite element method. The simulation is assumed under dynamic climatic conditions of Prague. As the results of the computational simulations showed, assuming analyzed amount of zeolite, any positive effect of on freeze/thaw resistance was not found related to unprotected building envelope. However, the results indicated, hygrothermal performance of zeolite concrete can be very considerate to applied external layers and thus extend their service life.

scholarly journals PREPARATION, CHARACTERIZATION OF BIOCHAR FOR A SUSTAINABLE SOIL HEALTH

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Rekha A. ◽  
Vidhya A.
Keyword(s):  
Soil Health ◽  
Physicochemical Characteristic ◽  
High Water ◽  
Exchange Capacity ◽  
Climatic Conditions ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Bet Analysis ◽  
Thermochemical Processes

Recent research suggests that biochar is a promising approach to minimize soil contamination caused by heavy metals and organic pollutants. It is also involved in the amendment of soil by altering the nutrients, pH and other factors. Through intensive literature review, this paper was aimed to better understand the selection of feedstock processes, preparation, and characterization of biochar. Wide variety of feedstock used for the biochar production based on the cost effectiveness, ease availability and they are ecofriendly to the environment. Among the thermochemical processes, pyrolysis is the promising techniques followed for the production of BC. The stabilization efficacy was mainly determined by cation exchange capacity, pH, and ash content of the biochar. The physicochemical characteristic of the biochar is analyzed using various methods such as SEM, FTIR, TGA and BET analysis. The surface area plays a major role in the metal sorption. The quality characteristics of biochar as a soil amendment varied greatly with the feedstock materials and the pyrolysis conditions. Biochar plays a great role in increasing the pH which helps the acidic soil region and its high-water retention capacity enhance the moisture level in the soil which enhances the microbial communities and its activity. Biochar becomes stabilized in the soil by interacting with soil particles. The inherent characteristics of the biochar as dictated by feedstock and pyrolysis conditions, interact with climatic conditions such as precipitation and temperature to influence how long biochar carbon remains stored in the soil. Due to its carbon sequestration in the soil, it helps in increasing the fertility of the soil and also enhances the crop yield.

scholarly journals Improving the Accuracy of a Hygrothermal Model for Wood-Frame Walls: A Cold-Climate Study

Buildings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 236
Author(s):  
Charles R. Boardman ◽  
Samuel V. Glass
Keyword(s):  
Field Study ◽  
Material Property ◽  
Oriented Strand Board ◽  
Field Measurements ◽  
Cold Climate ◽  
Latex Paint ◽  
Kraft Paper ◽  
Humidity Measurements ◽  
Wood Frame ◽  
Improved Model

A one-dimensional transient hygrothermal model was used to simulate eight different wood-frame wall assemblies. Simulations were compared with measured results from a two-year field study exploring the effects of exterior insulation on wall moisture performance in a cold-climate. The field study documented the moisture content, temperature, and relative humidity measurements in wall assemblies using oriented strand board (OSB) sheathing. Simulations were performed using generic design input values as well as input values based on measurements or sensitivity analysis. Laboratory material property measurements informed the choice of material property values in the improved model for OSB, asphalt-coated kraft paper, and interior latex paint. Simulations using improved input values typically agreed with field measurements within measurement error. The most significant model improvements were all related to vapor permeance. The vinyl siding used an effective permeance much lower than typically recommended. However, both the extruded polystyrene insulation and the asphalt-coated kraft paper facing on the cavity fiberglass insulation had higher permeance than literature values.

Long Term Performance of Fusion Bond Epoxy Coated Pipelines

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.

Climatic conditions over the estuary and Firth of Forth, Scotland

1987 ◽  
Vol 93 (3-4) ◽  
pp. 245-258
Author(s):  
S. J. Harrison
Keyword(s):  
East Coast ◽  
High Water ◽  
Surface Interactions ◽  
Climatic Conditions ◽  
Heat Fluxes ◽  
Spatial And Temporal Scales ◽  
Surface Heat Fluxes ◽  
Air Movement ◽  
Tidal Water ◽  
Firth Of Forth

SynopsisThe pattern of climatic variation over estuaries and their environs is, to a considerable extent, controlled by aspect, slope and elevation in addition to orientation of the major relief features with respect to the movement of principal weather systems. Data from the few climatological stations within the immediate vicinity of the estuary and Firth of Forth demonstrate the essentially maritime nature of climate, and indicate also that there is a dominantly west–east gradient of change in most climatological variables. Below the high water mark the movement of water in tidal ebb and flow and river inflow modify atmosphere–surface interactions over relatively short spatial and temporal scales. Observations from a fixed instrument tower on Skinflats in the middle estuary and from Inchkeith Lighthouse indicate that tidal water movements exert varying degrees of control over sub-surface heat fluxes, air movement in the atmospheric boundary layer and the inland penetration of coastal weather systems such as the typical east coast haar.

scholarly journals Long-Term Performance of Trestle Bridges: Case Study of an Indonesian Marine Port Structure

2020 ◽  
Vol 8 (5) ◽  
pp. 358 ◽  
Author(s):  
Yusak Oktavianus ◽  
Massoud Sofi ◽  
Elisa Lumantarna ◽  
Gideon Kusuma ◽  
Colin Duffield
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Service Life ◽  
Field Measurement ◽  
Field Measurements ◽  
Element Analysis ◽  
Moment Capacity ◽  
Non Destructive

A precast reinforced concrete (RC) T-beam located in seaport Terminal Peti Kemas (TPS) Surabaya built in 1984 is used as a case study to test the accuracy of non-destructive test techniques against more traditional bridge evaluation tools. This bridge is mainly used to connect the berth in Lamong gulf and the port in Java Island for the logistic purposes. The bridge was retrofitted 26 years into its life by adding two strips of carbon fiber reinforced polymer (CFRP) due to excessive cracks observed in the beams. Non-destructive field measurements were compared against a detailed finite element analysis of the structure to predict the performance of the girder in terms of deflection and moment capacity before and after the retrofitting work. The analysis was also used to predict the long-term deflections of the structure due to creep, crack distribution, and the ultimate moment capacity of the individual girder. Moreover, the finite element analysis was used to predict the deflection behavior of the overall bridge due to vehicle loading. Good agreement was obtained between the field measurement and the analytical study. A new service life of the structure considering the corrosion and new vehicle demand is carried out based on field measurement using non-destructive testing. Not only are the specific results beneficial for the Indonesian port authority as the stakeholder to manage this structure, but the approach detailed also paves the way for more efficient evaluation of bridges more generally over their service life.

Estimation of evapotranspiration from rice in southern New South Wales: a review

1994 ◽  
Vol 34 (7) ◽  
pp. 1069 ◽  
Author(s):  
E Humphreys ◽  
WS Meyer ◽  
SA Prathapar ◽  
DJ Smith
Keyword(s):  
Water Use ◽  
New South ◽  
Meteorological Data ◽  
Strong Dependence ◽  
New South Wales ◽  
Radiant Energy ◽  
Field Measurements ◽  
High Water ◽  
Management Plan ◽  
South Wales

This paper reviews field measurements of evapotranspiration from rice (ET rice) in the Murrumbidgee Valley of southern New South Wales. The results are compared with US Class A open pan evaporation (E pan) at CSIRO Griffith, and with reference evapotranspiration (ETo) calculated using a locally calibrated Penman equation. Both methods (+ETrice = +Epan or +ETrice = +ETo) give good estimates of total evapotranspiration from flooded rice over the ponded season of about 5 months, from October to February. Variation between seasons in total ETo, rainfall, and ETo minus rainfall is large. Over 32 years, total seasonal ETo varied by a factor of 1.5, while rainfall varied >10-fold. The irrigation water requirement for rice +(ETo - rainfall) varied from 685 mm in 1992-93 to 1350 mm in 1990-91. This large variation highlights the need to adjust the rice water use limit (16 ML/ha or 1600 mm) on a seasonal basis, to detect and eliminate high water use paddocks where percolation to the groundwater or surface runoff is excessive (>2 ML/ha). On average, an irrigation requirement of 10.5 ML/ha is needed to replace net evaporative loss +(ETo - rainfall) for rice flooded for 5 months, October-February. Monthly totals of ETo are compared for several locations within the rice-growing areas of southern New South Wales, and differences between locations are found to be small and not significant. This reflects the strong dependence of evaporation on radiant energy, which is unlikely to vary spatially to a significant extent across the region. ETo calculated from meteorological data collected at CSIRO Griffith therefore provides a definitive basis for estimating evapotranspiration from rice in southern New South Wales. Furthermore, CSIRO Griffith has a computerised meteorological data base going back to the 1930s. Current meteorological data and historical records are readily available by contacting the Metdata Manager. Therefore, the case is made for using CSIRO Griffith ETo as the reference for estimating evapotranspiration from rice in southern New South Wales. This study provides farmers, Land and Water Management Plan groups, and policy makers with a tool that can be used, on a yearly basis, to evaluate rice paddock water use efficiency. It should be adopted to confine rice growing to the least permeable soils.

scholarly journals The Effects of the Internal Flow Structure on SPM Entrapment in the Rotterdam Waterway

2010 ◽  
Vol 40 (11) ◽  
pp. 2357-2380 ◽  
Author(s):  
Michel A. J. de Nijs ◽  
Johan C. Winterwerp ◽  
Julie D. Pietrzak
Keyword(s):  
Abrupt Change ◽  
Tidal Flow ◽  
Three Dimensional ◽  
Internal Flow ◽  
Field Measurements ◽  
High Water ◽  
Transport Pathways ◽  
Salt Wedge ◽  
Suspended Particulate ◽  
Bed Stress

Abstract Field measurements are presented, which are the first to quantify the processes influencing the entrapment of suspended particulate matter (SPM) at the limit of saltwater intrusion in the Rotterdam Waterway. The estuarine turbidity maximum (ETM) is shown to be maintained by the trapping of fluvial SPM at the head of the salt wedge. The trapping process is associated with the raining out of fluvial SPM from the upper, fresher part of the water column, into the layer below the pycnocline. The dominant mechanisms responsible are baroclinic shear flows and the abrupt change in turbulent mixing characteristics due to damping of turbulence at the pycnocline. This view contrasts with the assumption of landward transport of marine SPM by asymmetries in bed stress. The SPM transport capacity of the tidal flow is not fully utilized in the ETM, and the ETM is independent of a bed-based supply of mud. This is explained by regular exchange of part of the ETM with harbor basins, which act as efficient sinks, and that the Rotterdam Waterway is not a complete fluvial SPM trap. The supply of SPM by the freshwater discharge ensures that the ETM is maintained over time. Hence, the ETM is an advective phenomenon. Relative motion between SPM and saltwater occurs because of lags introduced by resuspension. Moreover, SPM that lags behind the salt wedge after high water slack (HWS) is eventually recollected at the head. Hence, SPM follows complex transport pathways and the mechanisms involved in trapping and transport of SPM are inherently three-dimensional.

Sign in / Sign up

Export Citation Format

Share Document