Frost Heave and Water Uptake Relations in Variably Saturated Aggregate Base Materials

2003 ◽  
Vol 1821 (1) ◽  
pp. 13-19 ◽  
Author(s):  
W. Spencer Guthrie ◽  
åke Hermansson
Keyword(s):  
Base Material ◽  
Primary Source ◽  
Frost Heave ◽  
Soil Conditions ◽  
Freezing Process ◽  
Freezing Front ◽  
Base Materials ◽  
Additional Water ◽  
Initial Freezing ◽  
Aggregate Base

The occurrence of frost heave in soils and aggregates can be attributed to the redistribution of water in the soil profile. Frost heave testing performed in this study on 71 variably saturated specimens of aggregate base material indicates that although the uptake of new water from outside the soil body is a primary source of moisture in the formation of segregation ice, internal water residing within the soil or aggregate structure can serve as an important supply of water to the freezing front. Frost heave concepts relating to unsaturated soil conditions were reviewed, and a laboratory methodology was employed to study the relationships between the physical properties of the specimens and their frost heave behavior. Degrees of saturation ranging from 45% to 84% were evaluated, and heave–uptake ratios as high as 2.24 were calculated. Ratios less than 1.09 suggest that sufficient porosity exists in the sample matrix to allow the formation of ice without causing frost heave; higher ratios designate samples that are nearly saturated and that undergo substantial upward redistributions of existing water during the initial freezing process, which gives rise to measurable heave even before additional water is imbibed by the sample. The entry of air into freezing soils and aggregates can play an important role in their frost heave behavior.

Intermittent freezing mode to reduce frost heave in freezing soils — experiments and mechanism analysis

2012 ◽  
Vol 49 (6) ◽  
pp. 686-693 ◽  
Author(s):  
Yang Zhou ◽  
Guoqing Zhou
Keyword(s):  
Growth Process ◽  
Frost Heave ◽  
Silty Clay ◽  
Mechanism Analysis ◽  
Test Results ◽  
Practical Application ◽  
Freezing Front ◽  
Freezing Test ◽  
Initial Freezing ◽  
Step Type

Two types of freezing tests have been conducted on Xuzhou silty clay. The intermittent freezing test results show that the frost heave increases step by step after the initial freezing stage, and its total amount is only 48.8% that resulting from the continuous freezing test. A model describing the growth process of the active ice lens in saturated, rigid soils has been established, and the importance of the frozen fringe is investigated in the model. The growth processes of the final ice lenses in the two freezing tests have been used for laboratory validation of the model, and the calculated results are in general agreement with the experimental data. The mechanism of using an intermittent freezing mode to reduce frost heave has been revealed by analyzing the growth process of the final ice lens. We indicate that, during the noncooling stage, the backward movement of the freezing front, which causes the disappearance of the frozen fringe, stops the growth of the final ice lens. This effect results in a step-type frost heave curve in the intermittent freezing test and reduces the heave amount effectively. Finally, problems concerning the practical application of the intermittent freezing mode are discussed in a preliminary manner.

Using Suction and Dielectric Measurements as Performance Indicators for Aggregate Base Materials

1997 ◽  
Vol 1577 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Tom Scullion ◽  
Timo Saarenketo
Keyword(s):  
Capillary Rise ◽  
High Surface ◽  
Base Material ◽  
Cold Weather ◽  
Base Materials ◽  
Aggregate Sample ◽  
Flexible Base ◽  
Granular Base ◽  
Aggregate Base ◽  
Moisture Conditions

A simple laboratory test for evaluating unstabilized granular base material is introduced. The test consists of monitoring the capillary rise of moisture within a 300-mm-high cylinder of compacted aggregate. The moisture conditions at the aggregate surface are monitored with a dielectric probe. A graph of surface dielectric versus time is used as the basis for performance classification. The poorest-performing materials are those that rapidly reach saturation and exhibit high surface dielectric values. The dielectric is a measure of the “free” or unbound water within the aggregate sample. It is not a simple measure of the moisture content of the material but an assessment of the state of bonding of the water within the fine aggregates. It is this unbound water that is thought to be directly related to the strength of the material and to its ability to withstand repeated freeze-thaw cycling. This test was developed by the Finnish National Road Administration and successfully used to investigate a major flexible base failure. The test is now under evaluation in Texas, where several Panhandle districts have reported cold-weather pavement cracking problems that they have attributed to the flexible bases. The test setup and equipment used are described, and test results from several base materials are presented. Also discussed are laboratory results from a recently completed project comparing eight Texas and four Finnish aggregates. One of the Finnish aggregates was classified as a poor performer; the remaining three were good performers. All of the Texas aggregates were rated as inferior to the high-quality Finnish aggregates. If this test is found to be successful in discriminating good- from bad-performing materials, it could be used to flag potentially poor performers and to evaluate the effectiveness of different base improvement techniques such as chemical stabilization or fines replacement.

Deposition of YSZ Layer by PS-PVD on Different Materials

2021 ◽  
Vol 320 ◽  
pp. 72-76
Author(s):  
Marek Góral ◽  
Tadeusz Kubaszek ◽  
Marek Poręba ◽  
Małgorzata Wierzbińska
Keyword(s):  
Vapour Deposition ◽  
Base Material ◽  
Deposition Process ◽  
Ceramic Layer ◽  
Process Time ◽  
Lower Plasma ◽  
Powder Feed Rate ◽  
Plasma Energy ◽  
Base Materials ◽  
Typical Process

Plasma Spray Physical Vapour Deposition (PS-PVD) method was designed for production of ceramic layer on nickel superalloys. In typical process before deposition the base material is heated by plasma up to 900 °C. In present article the yttria stabilized zirconia (YSZ) was deposited on low melting point materials: 2017A-type aluminium alloy and Cu-ETP copper. The influence of power current, process time and powder feed rate on structure and thickness of obtained coatings was analysed. During first deposition process the overheating of Al-sample was observed and as result the power current was decreased to 1600 A. In the next experimental the approx. 5 mm thick dense coating was formed. During experimental processes of YSZ deposition on copper the thickness of coating increased from approx. 5 to 22 mm. The copper-oxide layer was formed under ceramic layer. The microscopic assessment showed the difficulties in formation of columnar ceramic layer on use base materials. The obtained coating was characterized by dense structure as a result of lower plasma energy during process. The increasing of power current is not possible in the case of overheating of base material.

scholarly journals Kajian Eksperimental Koefisien Redaman Akustik Bahan Pelapis Plat Dek Kapal

2018 ◽  
Vol 3 (1) ◽  
pp. 41
Author(s):  
Wibowo Harso Nugroho ◽  
Nanang J.H. Purnomo ◽  
Hardi Zen ◽  
Andi Rahmadiansah
Keyword(s):  
Absorption Coefficient ◽  
High Frequency ◽  
Transmission Loss ◽  
Base Material ◽  
Sound Insulation ◽  
Insulation Material ◽  
Base Materials ◽  
Specimen Material ◽  
Ship Classification ◽  
Technical Assessment

With the increasingly strict requirements of the ship classification bureau for permissible noise limits to allow passengers and crew to be more comfortable and secure a technical assessment is required to address the characteristics of the noise. A noise beyond the standard allowed in the vessel can be a problem to the ship operators. This noise problem will greatly affects the crews' comfort and passengers. One method to reduce the noise on a ship is to use sound insulation. This paper describes the method for determining the absorption coefficient α and the transmission loss (TL) through an acoustic test of a concrete insulation in the laboratory. The test was conducted by using the method of impedance tube where a speciment response measured by a microphone. In general, the properties of this insulation material remains as the main base material which is concrete. it has been found that the transmission loss value (TL) is in the range of 10 - 50 dB whereas for the base material the concrete is around 22 - 49 dB but the absorption coefficient α of the specimen material is much higher than the material of the base material especially in high frequency, which ranges from 0.15 to 0.97, whereas for concrete base materials have absorbent coefficient α ranges from 0.01 to 0.02.

scholarly journals Enhancement of the Tensile and the Compression Properties for Heat- Cured Acrylic Resin Denture Base Materials

2018 ◽  
Vol 15 (4) ◽  
pp. 449-454
Author(s):  
Baghdad Science Journal
Keyword(s):  
Polymethyl Methacrylate ◽  
Compression Strength ◽  
Base Material ◽  
Acrylic Resin ◽  
Tensile Tests ◽  
Strength Test ◽  
Denture Base ◽  
Compression Properties ◽  
Base Materials ◽  
Styrene Butadiene

This work aims to investigate the tensile and compression strengths of heat- cured acrylic resin denture base material by adding styrene-butadiene (S- B) to polymethyl methacrylate (PMMA). The most well- known issue in prosthodontic practice is fracture of a denture base. All samples were a blend of (90%, 80%) PMMA and (10%, 20%) S- B powder melted in Oxolane (Tetra hydro furan). These samples were chopped down into specimens of dimensions 100x10x2.5mm to carry out the requirements of tensile tests. The compression strength test specimens were shaped into a cylinder with dimensions of 12.7mm in diameter and 20mm in length. The experimental results show a significant increase in both tensile and compression strengths when compared to control (standard) results for the preparation material.

scholarly journals Prediction Model of Elastic Modulus for Granular Road Bases

2020 ◽  
Vol 2 (1) ◽  
pp. p35
Author(s):  
Zainab Ahmed Alkaissi ◽  
Hassan Adnan
Keyword(s):  
Elastic Modulus ◽  
Linear Regression Analysis ◽  
Base Material ◽  
Recycled Concrete ◽  
Dry Density ◽  
Concrete Aggregate ◽  
Vertical Loading ◽  
Base Materials ◽  
Granular Base ◽  
Road Bases

The estimation of elastic modulus for road bases is the primary objective of this research which is implemented a significant role in transmitting the vertical loading to the pavement foundation layers. In this study, the effect of weathering conditions on the stiffness of base course is investigated and implied the durability test by subjecting the prepared samples to a different numbers of wet-dry cycles (0,2, 4, 6, 8 and 10). A conventional base materials of local natural gravel aggregate and treated base materials with recycled concrete aggregate RCA at different percentages (0%, 25%, 50% 75% and 100%) is adopted in this research. The elastic characteristics are estimated in terms of elastic modulus. Elastic modulus are estimated by passing the ultrasonic pulse velocity through the untreated and treated base materials laboratory specimens. This test can be used to study the elastic modulus properties of base materials. A multiple linear regression analysis is used for prediction the elastic modulus using the SPSS (software ver.21). Elastic Modulus (kPa) is the dependent variable whereas the independent variable are; No. of wet- dry cycle and Percent (%) of RCA stabilizer. The obtained results for elastic modulus (Es) of granular base material layer showed increasing in elastic modulus with percentage of RCA%., results revealed that the (Es) values reached a maximum value of (6927kPa) for 100%. For the OMC’s values increases due to the percentage increment of RCA in granular base material mixture, this increment in water contents is refer to high absorption capacity of the paste clinging to the RCA. On other side the dry density decrease gradually with adding percentage of (RCA) in granular base material mixture.

Influence of the base material on the mechanical behaviors of polycrystal-like meta-crystals

2021 ◽  
pp. 2150004
Author(s):  
J. Lertthanasarn ◽  
C. Liu ◽  
M.-S. Pham
Keyword(s):  
Synergistic Effects ◽  
High Surface ◽  
Base Material ◽  
High Strength ◽  
Yield Stability ◽  
Yield Behavior ◽  
Specific Strength ◽  
Base Materials ◽  
Lattice Materials ◽  
Strength And Stiffness

Architected lattice metamaterials offer extraordinary specific strength and stiffness that can be tailored through the architecture. Meta-crystals mimic crystalline strengthening features in crystalline alloys to obtain high strength and improved post-yield stability of lattice materials. This study investigates synergistic effects of the base material’s intrinsic crystalline microstructure and architected polycrystal-like architecture on the mechanical behavior of architected metamaterials. Four different polygrain-like meta-crystals were fabricated from 316L, Inconel 718 (IN718) and Ti6Al4V via laser powder bed fusion (L-PBF). While the elastic modulus of the meta-crystals did not vary significantly with the base material or the number of meta-grains, the strength of the meta-crystals showed strong increasing correlation with reducing the size of meta-grains. The differences between meta-crystals made by the three alloys were the most substantial in the post-yield behavior, where the 316L meta-crystals were the most stable while Ti6Al4V meta-crystals were the most erratic. The differences in the post-yield behavior were attributed to the base material’s ductility and intrinsic work-hardening. For all base materials, increasing the number of meta-grains improved the post-yield stability of meta-crystals. The tolerance to the processing defects also differed with the base material. Detrimental defects such as the high surface roughness on the downskin of the struts or the large, irregularly shaped pores near the surface of the struts led to early strut fracture in Ti6Al4V meta-crystals. In contrast, ductile IN718 was able to tolerate such defects, enabling the most significant synergistic strengthening across lengthscales to achieve architected materials of low relative density, but with a very high strength and an excellent energy absorption.

Influence of the Glassfiber Filaments Distribution on Quality and Performance of Hole Processing on Printboards

2019 ◽  
Vol 946 ◽  
pp. 223-227
Author(s):  
Aleksey N. Shulgin ◽  
Aleksandr A. Dyakonov ◽  
Anastasia E. Gorodkova
Keyword(s):  
Glass Fibers ◽  
Maximum Shear Stress ◽  
Base Material ◽  
Dielectric Materials ◽  
Basic Material ◽  
Manufacturing Cost ◽  
Base Materials ◽  
Material Choice ◽  
And Performance ◽  
A Chain

The description of the basic material for the printboards production is given, its basic physical properties are formulated, the features of machining are shown and the range of problems that arise in this case is determined. We specified common mistakes that could lead to mass marriage in the manufacture of printboard assemblies. The structure and composition of base materials for the production of clad dielectric materials are described in this paper. An equation for calculating the maximum shear stress for a composite material is given. It is shown that nesting and, as a consequence, an increased content of glass fibers through a chain of interrelated factors affects the quality and reliability of the printboard operation and the entire product as a whole. In addition, the dense laying of fibers increases the cutting tool wear significantly. The article provides the technique of the base material choice depending on the distribution structure of glassfiber filaments on which the labor productivity, the quality, the cutter power and the manufacturing cost of the printboards depends.

Separate-ice frost heave model for one-dimensional soil freezing process

2017 ◽  
Vol 13 (1) ◽  
pp. 207-217 ◽  
Author(s):  
Guo-qing Zhou ◽  
Yang Zhou ◽  
Kun Hu ◽  
Yi-jiang Wang ◽  
Xiang-yu Shang
Keyword(s):  
Soil Freezing ◽  
Frost Heave ◽  
Freezing Process ◽  
One Dimensional

Mechanical stabilization for the control of frost heave

1985 ◽  
Vol 12 (4) ◽  
pp. 899-905 ◽  
Author(s):  
R. J. Kettle ◽  
E. Y. McCabe
Keyword(s):  
Coarse Aggregate ◽  
Aggregate Size ◽  
Individual Characteristics ◽  
Frost Heave ◽  
Freezing Process ◽  
Natural Soil ◽  
Soil Matrix ◽  
Mechanical Stabilization ◽  
The Matrix

This paper is concerned with the role of mechanical stabilization in controlling frost susceptibility. This has been assessed in terms of the heave, developed over a 250 h period, of cylindrical specimens subjected to the Transport and Road Research Laboratory (United Kingdom) frost heave test. The basic soil matrix consisted of a highly susceptible mixture of sand and ground chalk. Three types of coarse particle (slag, basalt, limestone) were used as the stabilizing agent, and these were each subdivided into two particle groups: 20−3.35 mm and 37.5−20 mm.The introduction of up to 50% of the selected coarse aggregates produced various non-frost-susceptible mixtures. The influence of the coarse aggregate was very dependent on aggregate type but less dependent on aggregate size. The data have been examined to assess the role of these coarser particles in the freezing process, including the effects of their individual characteristics. This clearly demonstrated the possibility of using mechanical stabilization to control frost susceptibility and this was supported by the results of additional tests on natural soil. Heaving pressures are also reported and are examined in relation to the amount of aggregate added, nature of the aggregate, and particle size. The addition of coarse aggregate to the matrix is shown to reduce the measured heaving pressures. Key words: frost heave, heaving pressure, granular materials, mechanical stabilization.

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