Seasonal Variation of Moisture and Subsurface Layer Moduli

2000 ◽  
Vol 1709 (1) ◽  
pp. 98-107 ◽  
Author(s):  
Vincent Janoo ◽  
Kent Shepherd
Keyword(s):  
Seasonal Variation ◽  
Moisture Content ◽  
Subsurface Layer ◽  
Field Measurements ◽  
General Description ◽  
Subsurface Temperature ◽  
Future Design ◽  
Pavement Structures ◽  
Base Course ◽  
Almost All

In 1995 the Montana Department of Transportation initiated a study on the seasonal variation of pavement strength, with an emphasis on spring thawing. Ten sites representing a cross section of Montana subgrade soil and pavement structure were selected and instrumented with moisture and temperature sensors. Field measurements of surface deflections, moistures, and temperatures were initiated in autumn 1996 and continued through the spring of 1997. The moisture and deflection data were used to determine the thaw-weakening characteristics of the sites and to develop subgrade modulus values for use in the future design of pavement structures using AASHTO mechanistic design methodology. Results indicated that in several areas not only the subgrade but also the base course layers were prone to thaw weakening. The length of thaw weakening varied from 4 days to a 3-week period. In addition, it was found that in almost all cases the subsurface moisture content began to increase rapidly when the subsurface temperature rose to around–2°C during the spring. In some cases it was found that when the subsurface temperature finally warmed to 0°C, the moisture content had reached its prefreeze value. This research provides a general description of the test sites and measurements; it quantifies the effects of thaw weakening on typical roads in Montana based on deflection and surface and subsurface moisture and temperature.

Seasonal Variation of Backcalculated Subgrade Moduli

1997 ◽  
Vol 1577 (1) ◽  
pp. 70-80 ◽  
Author(s):  
Bing Long ◽  
Mustaque Hossain ◽  
Andrew J. Gisi
Keyword(s):  
Seasonal Variation ◽  
Moisture Content ◽  
Temperature Effect ◽  
Resilient Modulus ◽  
Natural Soil ◽  
Temperature Regimes ◽  
Almost All ◽  
Moisture Conditions ◽  
Falling Weight ◽  
And Behavior

Seasonal variations in pavement material properties and behavior due to variations in temperature and moisture conditions are known to affect the structural performance of pavement. Temperature, subgrade moisture content, and falling weight deflectometer (FWD) deflection data were collected monthly on four asphalt pavement test sections for a year. Subgrade moduli were backcalculated using the elastic layer theory with two calculation schemes and pavement models. Backcalculation of subgrade moduli by subdividing the subgrade into a compacted subgrade layer and a natural soil subgrade layer resulted in compacted subgrade moduli that are more sensitive to the seasonal variation for all sites. It was found that for almost all sites, the patterns of subgrade response, in terms of subgrade moduli versus subgrade moisture content, simulated sine-shaped forms signifying a temperature effect. The temperature effect was confirmed by the strong correlation between backcalculated subgrade moduli and pavement surface temperature during FWD tests. The lowest backcalculated subgrade moduli were obtained for two sections during months when asphalt surface temperatures were excessively high (greater than 40°C). Both backcalculation schemes showed similar trends in variation of subgrade moduli over seasons. When the AASHTO relative damage concept was used to compute the effective roadbed soil resilient modulus for design, similar values were found for both schemes for most of the sites. The minimum frequency of FWD testing to capture the seasonal variation of subgrade was found to be three tests per year, or testing every fourth month, assuming that unusually high temperature regimes could be avoided.

CLT construction without weather protection requires extensive moisture control

2021 ◽  
pp. 174425912199638
Author(s):  
Lars Olsson
Keyword(s):  
Moisture Content ◽  
Field Measurements ◽  
Scientific Work ◽  
Field Studies ◽  
Microbiological Analysis ◽  
Mould Growth ◽  
Extensive Growth ◽  
Almost All ◽  
Dry Out ◽  
Moisture Conditions

This study examines how cross-laminated timber (CLT) constructions, including joints, connections and attachment points, are affected by precipitation during construction. The case studies are based on moisture content measurements and material sampling as well as microbiological analysis during the structure’s construction stage. The study does not include remediation control. The field measurements show microbiological growth in all buildings and almost all floor structures that were investigated. Of a total of 200 measuring points analysed, half had mould growth and around a third had moderate or extensive growth. The moisture content measurements for one of the locations with the largest percentage of elevated or high moisture content was at the top of the floor structure in the bottom gap between timbers in the CLT top layer. This is one example of several materials or construction components where there is limited possibility of dry out. Based on the outcome, it would appear difficult, or impossible, to avoid the appearance of microbial growth during construction with CLT without weather protection. Previous studies indicate that microbiological analysis of CLT is extremely rare in both laboratory and field studies, which implies that there are obvious shortcomings in the scientific work. The fact that mould growth is often invisible needs to be disseminated, especially in practical studies. However, there seems to be a good level of awareness in the literature that theoretical studies often conduct mould growth risk evaluations. There do not appear to be any moisture safety assembly methods or solutions for CLT construction that do not have weather protection or a declaration of the critical moisture conditions for CLT products.

A Comparative Study on the Noise between Floors of Apartment and Multiplex Housing

2015 ◽  
Vol 752-753 ◽  
pp. 1232-1235
Author(s):  
Ji Hun Kim ◽  
Yoon Seok Shin
Keyword(s):  
Comparative Analysis ◽  
Comparative Study ◽  
Field Measurements ◽  
Apartment Building ◽  
Noise And Vibration ◽  
Korean Government ◽  
Current State ◽  
The Future ◽  
House Type ◽  
Almost All

Since recently almost all housing built in Korean have shared walls and floor, diverse problems are unavoidable including noise between floor arising from noise and vibration. Many efforts have been made by the Korean government, but the number of complaints related with the noise between floors has been gradually increasing. Therefore, through the field measurements by house type, the current state of noise was understood. To do this, the noise between floors was measured in an apartment household and a multiplex house to perform a comparative analysis. As the result, the differences in the noise between the two house types were clarified. The findings of this research are expected to contribute to reduction of the noise between floors in an apartment building in the future.

Assessment of Moisture Content in Sandy Beach Environments from Multispectral Satellite Imagery

2021 ◽  
Author(s):  
Julie Paprocki ◽  
Nina Stark ◽  
Hans C Graber ◽  
Heidi Wadman ◽  
Jesse E McNinch
Keyword(s):  
Moisture Content ◽  
Laboratory Data ◽  
Field Measurements ◽  
Weather Conditions ◽  
Sandy Beaches ◽  
Percent Error ◽  
Moisture Contents ◽  
Multispectral Satellite Imagery ◽  
Factor C

A framework for estimating moisture content from satellite-based multispectral imagery of sandy beaches was tested under various site conditions and sensors. It utilizes the reflectance of dry soil and an empirical factor c relating reflectance and moisture content for specific sediment. Here, c was derived two ways: first, from in-situ measurements of moisture content and average NIR image reflectance; and second, from laboratory-based measurements of moisture content and spectrometer reflectance. The proposed method was tested at four sandy beaches: Duck, North Carolina, and Cannon Beach, Ocean Cape, and Point Carrew, Yakutat, Alaska. Both measured and estimated moisture content profiles were impacted by site geomorphology. For profiles with uniform slopes, moisture contents ranged from 3.0%-8.0% (Zone 1) and from 8.0%-23.0% (Zone 2). Compared to field measurements, the moisture contents estimated using c calibrated from in-situ and laboratory data resulted in percent error of 3.6%-44.7% and 2.7%-58.6%, respectively. The highest percent error occurred at the transition from Zone 1 to Zone 2. Generally, moisture contents were overestimated in Zone 1 and underestimated in Zone 2, but followed the expected trends based on field measurements. When estimated moisture contents in Zone 1 exceeded 10%, surface roughness, debris, geomorphology, and weather conditions were considered.

The Snow Ski as a Dynamic System

1972 ◽  
Vol 94 (2) ◽  
pp. 133-138 ◽  
Author(s):  
R. L. Piziali ◽  
C. D. Mote
Keyword(s):  
Dynamic System ◽  
Laboratory Testing ◽  
Research Laboratory ◽  
Field Measurements ◽  
Static System ◽  
Testing Procedures ◽  
Future Design ◽  
Meaningful Information ◽  
Physical Information ◽  
System Characteristics

Paper reports research on dynamic system characteristics of snow skis. Laboratory and field measurements of frequency response, running surface pressure excitation, and static system characteristics are intended to provide a data base of physical information to guide future design and research. Laboratory testing procedures used give meaningful information for “straight running” but not for “turning.” In general, the turning and straight running maneuvers must be examined independently. This paper summarizes the general research observations with a minimum of detail included.

Effect of Transitions in the Water Table and Soil Moisture Content on the Cathodic Protection of Buried Pipelines

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Fraser King ◽  
Russell Given ◽  
Robert G. Worthingham ◽  
Greg Van Boven
Keyword(s):  
Moisture Content ◽  
Water Table ◽  
Cathodic Protection ◽  
Field Measurements ◽  
Field Trials ◽  
High Resistivity ◽  
Buried Pipelines ◽  
Pipe Surface ◽  
Degree Of Protection ◽  
O2 Concentration

Buried pipelines can be subject to transitional environments due to changes in soil type or moisture content. Changes in the height of the water table, for example, will affect not only the availability of water but also the access of oxygen to the pipe surface. Transitions between different soil types will also result in different exposure conditions for different parts of the pipe. These variations can affect the distribution of potential on the pipe surface and the ability of the CP system to provide adequate protection. A combination of laboratory-scale soil box tests and field measurements on operating pipelines has been used to study the effect of varying moisture content and water level on the level of cathodic protection and on pipe-depth environmental conditions. In both laboratory tests and field trials, the degree of protection was found to depend on the availability of cathodic reactants (O2 and/or H2O). Ingress of O2 results in a positive shift in potential as more current is required to electrochemically reduce the oxidant and the pipe is less easily polarized. Under some circumstances, the ingress of water has the same effect. Although more aerobic conditions lead to more positive potentials, the pipe is not necessarily less well protected. In many dry and/or high resistivity soils, the pipe surface may well be passive because of the high interfacial pH and/or high O2 concentration.

scholarly journals Long-Term Performance of Pavement Structures with Cold In-Place Recycled Base Course

2021 ◽  
Vol 16 (2) ◽  
pp. 48-65
Author(s):  
Audrius Vaitkus ◽  
Judita Gražulytė ◽  
Andrius Baltrušaitis ◽  
Jurgita Židanavičiūtė ◽  
Donatas Čygas
Keyword(s):  
Asphalt Pavement ◽  
Asphalt Mixture ◽  
Asphalt Pavements ◽  
Recycled Asphalt ◽  
Binding Agents ◽  
Pavement Structure ◽  
Pavement Structures ◽  
Base Course ◽  
Surface Distress ◽  
Foamed Bitumen

Properly designed and maintained asphalt pavements operate for ten to twenty-five years and have to be rehabilitated after that period. Cold in-place recycling has priority over all other rehabilitation methods since it is done without preheating and transportation of reclaimed asphalt pavement. Multiple researches on the performance of cold recycled mixtures have been done; however, it is unclear how the entire pavement structure (cold recycled asphalt pavement overlaid with asphalt mixture) performs depending on binding agents. The main objective of this research was to evaluate the performance of cold in-place recycled asphalt pavements considering binding agents (foamed bitumen in combination with cement or only cement) and figure out which binder leads to the best pavement performance. Three road sections rehabilitated in 2000, 2003, and 2005 were analysed. The performance of the entire pavement structure was evaluated in terms of the International Roughness Index, rut depth, and pavement surface distress in 2013 and 2017.

scholarly journals A Study on Factors Influencing the Determination of Moisture Content of Fibrous Peat

2011 ◽  
Vol 2 (2) ◽  
pp. 39-47 ◽  
Author(s):  
Pui Tau Shien ◽  
Seneviratne H.N. ◽  
Dygku Salma Awg Ismail
Keyword(s):  
Moisture Content ◽  
Particle Density ◽  
Peat Soil ◽  
Test Procedure ◽  
Field Measurements ◽  
Standard Test ◽  
Moisture Loss ◽  
Fibrous Peat ◽  
Saturated Sample

Fibrous peat is an undrained peat that usually possesses very high moisture content. However, not all experimental procedures are applicable for determination of moisture content of fibrous peat. This research is aimed at examining the determination of insitu moisture content of fibrous peat using field measurements. The peat soil samples were collected at shallow depths from Asajaya at Kota Samarahan and Taman Kopodims at Matang , Kuching Sarawak by using peat auger. The laboratory tests such as determination of moisture content, fiber content, particle density and ash content were conducted on the collected samples in order to establish relationships between the parameters. Undisturbed peat samples from Matang were subjected to falling head permeability test to determine the saturated permeability. The saturated sample were then allowed to drain freely to simulate the moisture loss possible during sampling when samples were brought out of boreholes. The test results showed that moisture content varies according to the drying temperature and position of the soil sample (top, middle and bottom) during sampling. Comparing samples from both locations, peat soil from Kota Samarahan possessed higher moisture content. The saturated permeability of peat sample was in the range of 2.62 – 3.05 cm/s. The free draining trial showed that moisture loss during sampling significantly influence the moisture content measurement. The variation in value of moisture content for fibrous peat may occurs due to several factors such as existing ground water table, sampling method by boring, existing standard test procedure which is not suitable for peat soils requirement and also because of the physical properties which varied according to depth of soil.

scholarly journals The fluxgate magnetometer of the Low Orbit Pearl Satellites (LOPS): overview of in-flight performance and initial results

2021 ◽  
Vol 10 (2) ◽  
pp. 227-243
Author(s):  
Ye Zhu ◽  
Aimin Du ◽  
Hao Luo ◽  
Donghai Qiao ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current System ◽  
Field Measurements ◽  
Stray Field ◽  
Fluxgate Magnetometer ◽  
General Description ◽  
Flight Performance ◽  
Spatial Coverage ◽  
Magnetic Field Measurements ◽  
Initial Results

Abstract. The Low Orbit Pearl Satellite series consists of six constellations, with each constellation consisting of three identical microsatellites that line up just like a string of pearls. The first constellation of three satellites were launched on 29 September 2017, with an inclination of ∼ 35.5∘ and ∼ 600 km altitude. Each satellite is equipped with three identical fluxgate magnetometers that measure the in situ magnetic field and its low-frequency fluctuations in the Earth's low-altitude orbit. The triple sensor configuration enables separation of stray field effects generated by the spacecraft from the ambient magnetic field (e.g., Zhang et al., 2006). This paper gives a general description of the magnetometer including the instrument design, calibration before launch, in-flight calibration, in-flight performance, and initial results. Unprecedented spatial coverage resolution of the magnetic field measurements allow for the investigation of the dynamic processes and electric currents of the ionosphere and magnetosphere, especially for the ring current and equatorial electrojet during both quiet geomagnetic conditions and storms. Magnetic field measurements from LOPS could be important for studying the method to separate their contributions of the Magnetosphere-Ionosphere (M-I) current system.

scholarly journals Comparisons between Asphalt Pavement Responses under Vehicular Loading and FWD Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Song Yang ◽  
Bing Qi ◽  
Zhensheng Cao ◽  
Shaoqiang Zhang ◽  
Huailei Cheng ◽  
...  
Keyword(s):  
Critical Strain ◽  
Asphalt Pavement ◽  
Field Measurements ◽  
Flexible Pavement ◽  
Fe Model ◽  
Wide Range ◽  
Vehicular Speed ◽  
Pavement Structures ◽  
Falling Weight ◽  
Strain Responses

The strain responses of asphalt pavement layer under vehicular loading are different from those under falling weight deflectometer (FWD) loading, due to the discrepancies between the two types of loadings. This research aims to evaluate and compare the asphalt layer responses under vehicular loading and FWD loadings. Two full-scale asphalt pavement structures, namely, flexible pavement and semirigid pavement, were constructed and instrumented with strain gauges. The strain responses of asphalt layers under vehicular and FWD loadings were measured and analyzed. Except for field measurements, the finite element (FE) models of the experimental pavements were established to simulate the pavement responses under a wide range of loading conditions. Field strain measurements indicate that the asphalt layer strain under vehicular loading increases with the rising temperature roughly in an exponential mode, while it decreases with the rising vehicular speed approximately linearly. The strain pulses in the asphalt layer generated by FWD loading are different from those induced by vehicular loading. The asphalt layer strains generated by FWD loading are close to those induced by low vehicular speed (35 km/h). The results from the FE model imply that the asphalt layer strains under FWD loading and vehicular loading are distributed similarly in the depth profile. For flexible pavement, the position of critical strain shifts gradually from the bottom of the asphalt layer to the mid-depth of the layer, as the temperature increases. For semirigid pavement, the position of critical strain is always located at the intermediate depth of the asphalt layer, regardless of temperatures.

Sign in / Sign up

Export Citation Format

Share Document