scholarly journals Resilient Response of Cement-Treated Coarse Post-Glacial Soil to Cyclic Load

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6495
Author(s):  
Katarzyna Zabielska-Adamska ◽  
Mariola Wasil ◽  
Patryk Dobrzycki
Keyword(s):  
Resilient Modulus ◽  
Axial Strain ◽  
Coarse Grained ◽  
Curing Time ◽  
Test Results ◽  
The Road ◽  
Compaction Energy ◽  
Load Sequence ◽  
Resilient Response ◽  
Compaction Method

Stabilisation with cement is an effective way to increase the stiffness of base and subbase layers and to improve the rutting of subgrade. The aim of the study is to investigate the effect of different percentages of cement additives (1.5%, 3.0%, 4.5% and 6.0%) on the resilient modulus of coarse-grained soil used on road foundations. The influence of the compaction method, the standard Proctor and the modified Proctor, as well as the sample curing time is analysed. The cement addition significantly increases the resilient modulus and reduces the resilient axial strain. Extending the curing time from 7 to 28 days also improves the resilient modulus. The change in the compaction energy from standard to modified does not increase the resilient modulus of the stabilised gravelly sand due to its compaction characteristics. The test results of the resilient modulus of the gravelly sand stabilised with cement indicate the possibility of using it as a material for the road base and subbase due to meeting the AASHTO requirements. However, the non-stabilised gravelly sand does not meet the above requirements. It has been sheared during cyclic tests at the first load sequence, regardless of the compaction method.

scholarly journals Pavement and Noise Reduction Performance of Open-Graded Asphalt Friction Course Improved by Waste Tire Crumb Rubber

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Ya Wang ◽  
Xianguang Wang ◽  
Liwen Zhang
Keyword(s):  
Noise Reduction ◽  
Resilient Modulus ◽  
Rubber Particle ◽  
Asphalt Mixture ◽  
Crumb Rubber ◽  
Test Results ◽  
The Road ◽  
Open Graded Friction Course ◽  
Road Performance ◽  
Reduction Effect

To further reveal the road performance and noise reduction performance of open-graded friction course (OGFC), the crumb rubber prepared by adding waste tires were considered, and the performance requirements of the material were put forward. To avoid the influence of rubber particle swelling on aggregate, the special gradation and mix proportion of OGFC mixture were designed, and the particle size of 4.75 mm was proposed as the control size. The test results show that the aggregate forms a good embedded structure. The resilient modulus, deformation performance, and fatigue performance of R-OGFC asphalt mixture with different crumb rubber contents were studied. According to the test results, the rubber particle content under the best road performance and noise reduction effect was proposed. The results show that, after adding a certain amount of crumb rubber, the performance of asphalt mixture has been greatly improved, especially the dynamic stability has been improved by 84%. Although the resilient modulus has decreased by 10%, the creep performance has decreased by 37%, and the fatigue life has decreased by 31% (2% rubber content), the noise reduction can reach 3.6–8.6 dB, and the noise reduction performance is significant. This shows that the best content of rubber particles is between 1.5% and 2%, and the R-OGFC mixture modified by rubber has a good application prospect.

scholarly journals Comparison of Mechanical Properties of Cement-Stabilized Loess Produced Using Different Compaction Methods

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Yingjun Jiang ◽  
Kejia Yuan ◽  
Qilong Li ◽  
Changqing Deng ◽  
Yong Yi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Cement Content ◽  
Resilient Modulus ◽  
Great Influence ◽  
Field Measurements ◽  
Vertical Vibration ◽  
Dry Density ◽  
Curing Time ◽  
Compaction Method

Mechanical properties are important indexes to evaluate the improvement effect and engineering performance of cement-stabilized loess (CSL). This paper presents a comparison of the mechanical properties of CSL compacted using hammer quasi-static compaction method (QSCM) and vertical vibration compaction method (VVCM). The compaction properties, unconfined compressive strength (UCS), splitting strength (SPS), and resilient modulus (RM) of the laboratory-compacted CSL using VVCM and QSCM are tested and compared. Furthermore, the effects of compaction method, cement content, compaction coefficient, and curing time of the CSL specimens are investigated. In addition, field measurements are carried out to validate the laboratory investigations. The results show that the laboratory-compacted CSL using VVCM has a larger dry density and smaller optimum water content than that using QSCM. And the compaction method has a great influence on the mechanical strength of CSL. The UCS, SPS, and RM of the specimen produced using VVCM are averagely 1.17 times, 1.49 times, and 1.17 times that of CSL produced using QSCM, respectively, and the UCS, SPS, and RM of the specimens produced using these two methods increase linearly as the cement content and compaction coefficient increase, while the mechanical strength growth curve experiences three periods of increasing sharply, increasing slowly, and stabilizing with the curing time increased. Moreover, the results also show that the mechanical properties of laboratory-compacted CSL using VVCM have a better correlation of 83.8% with the field core samples.

Hysteresis loss of ultra-large off-the-road tire rubber compounds based on operating conditions at mine sites

2021 ◽  
pp. 095440702110155
Author(s):  
Shaosen Ma ◽  
Guangping Huang ◽  
Khaled Obaia ◽  
Soon Won Moon ◽  
Wei Victor Liu
Keyword(s):  
Large Strain ◽  
Tensile Tests ◽  
Operating Conditions ◽  
Hysteresis Loss ◽  
Strain Rates ◽  
Test Results ◽  
Tire Rubber ◽  
The Road ◽  
Rubber Compounds ◽  
Mine Sites

The objective of this study is to investigate the hysteresis loss of ultra-large off-the-road (OTR) tire rubber compounds based on typical operating conditions at mine sites. Cyclic tensile tests were conducted on tread and sidewall compounds at six strain levels ranging from 10% to 100%, eight strain rates from 10% to 500% s−1 and 14 rubber temperatures from −30°C to 100°C. The test results showed that a large strain level (e.g. 100%) increased the hysteresis loss of tire rubber compounds considerably. Hysteresis loss of tire rubber compounds increased with a rise of strain rates, and the increasing rates became greater at large strain levels (e.g. 100%). Moreover, a rise of rubber temperatures caused a decrease in hysteresis loss; however, the decrease became less significant when the rubber temperatures were above 10°C. Compared with tread compounds, sidewall compounds showed greater hysteresis loss values and more rapid increases in hysteresis loss with the rising strain rate.

Improved AEB algorithm combined with estimating the adhesion coefficient of road ahead and considering the performance of EHB

2021 ◽  
pp. 095440702110261
Author(s):  
Dequan Zeng ◽  
Zhuoping Yu ◽  
Lu Xiong ◽  
Junqiao Zhao ◽  
Peizhi Zhang ◽  
...  
Keyword(s):  
Joint Probability ◽  
Principal Component ◽  
Test Results ◽  
Safe Distance ◽  
Adhesion Coefficient ◽  
The Road ◽  
Response Characteristics ◽  
Emergency Braking ◽  
Multiple Beams ◽  
Maximum Method

This paper proposes an improved autonomous emergency braking (AEB) algorithm intended for intelligent vehicle. Featuring a combination with the estimation of road adhesion coefficient, the proposed approach takes into account the performance of electronic hydraulic brake. In order for the accurate yet fast estimate of road ahead adhesion coefficient, the expectation maximization framework is applied depending on the reflectivity of ground extracted by multiple beams lidar in four major steps, which are the rough extraction of ground points based on 3 σ criterion, the accurate extraction of ground points through principal component analysis (PCA), the main distribution characteristics of ground as extracted using the expectation maximum method (EM) and the estimation of road adhesion coefficient via joint probability. In order to describe the performance of EHB, the response characteristics, as well as the forward and adverse models of both braking pressure and acceleration are obtained. Then, with two typical roads including single homogeneous road and fragment pavement, the safe distance of improved AEB is modeled. To validate the algorithm developed in this paper, various tests have been conducted. According to the test results, the reflectivity of laser point cloud is effective in estimating the road adhesion coefficient. Moreover, considering the performance of EHB system, the improved AEB algorithm is deemed more consistent with the practicalities.

scholarly journals Performance Evaluation of WMA Containing Re-Refined Acidic Sludge and Amorphous Poly Alpha Olefin (APAO)

2021 ◽  
Vol 13 (6) ◽  
pp. 3315
Author(s):  
Mansour Fakhri ◽  
Danial Arzjani ◽  
Pooyan Ayar ◽  
Maede Mottaghi ◽  
Nima Arzjani
Keyword(s):  
Resilient Modulus ◽  
Permanent Deformation ◽  
Road Construction ◽  
Moisture Damage ◽  
Asphalt Mixtures ◽  
Modified Bitumen ◽  
Alternative Source ◽  
The Road ◽  
Marshall Test ◽  
Alpha Olefin

The use of waste materials has been increasingly conceived as a sustainable alternative to conventional materials in the road construction industry, as concerns have arisen from the uncontrolled exploitation of natural resources in recent years. Re-refined acidic sludge (RAS) obtained from a waste material—acidic sludge—is an alternative source for bitumen. This study’s primary purpose is to evaluate the resistance of warm mix asphalt (WMA) mixtures containing RAS and a polymeric additive against moisture damage and rutting. The modified bitumen studied in this research is a mixture of virgin bitumen 60/70, RAS (10, 20, and 30%), and amorphous poly alpha olefin (APAO) polymer. To this end, Marshall test, moisture susceptibility tests (i.e., tensile strength ratio (TSR), residual Marshall, and Texas boiling water), resilient modulus, and rutting assessment tests (i.e., dynamic creep, Marshall quotient, and Kim) were carried out. The results showed superior values for modified mixtures compared to the control mix considering the Marshall test. Moreover, the probability of a reduction in mixes’ moisture damage was proved by moisture sensitivity tests. The results showed that modified mixtures could improve asphalt mixtures’ permanent deformation resistance and its resilience modulus. Asphalt mixtures containing 20% RAS (substitute for bitumen) showed a better performance in all the experiments among the samples tested.

Effects of Laumontite Hydration/Dehydration on Swelling Deformation and Slake Durability of Altered Granodiorite

2020 ◽  
Vol 26 (4) ◽  
pp. 507-516
Author(s):  
Junsong Yan ◽  
Junhui Shen ◽  
Kaizhen Zhang ◽  
Jianjun Xu ◽  
Weifeng Duan ◽  
...  
Keyword(s):  
Axial Strain ◽  
Test Results ◽  
X Ray Diffraction ◽  
Dam Foundation ◽  
Hydro Power ◽  
Slake Durability Index ◽  
Slake Durability ◽  
Dehydration Reactions ◽  
Short Period ◽  
Durability Index

ABSTRACT The mineral laumontite can undergo hydration/dehydration reactions at room temperature. The hydration/dehydration produces a 3 to 6 percent volume change in the unit cell. The effects of laumontite hydration/dehydration on swelling and slake durability were investigated using altered granodiorite containing laumontite from the dam foundation of Yangfanggou Hydro Power Station, Sichuan, China. The occurrence of laumontite in altered rocks was first determined by petrological analysis. Typical samples were then collected for laboratory X-ray diffraction (XRD) analyses, free swelling tests, and slake durability index (SDI) tests. The test results were analyzed to determine the quantitative relationships between laumontite content, maximum axial strain, and slake durability index. We found that hydration of laumontite led to rock swelling. As laumontite content increased, maximum axial strain increased linearly; if water penetrated the rock quickly, swelling occurred over a short period. The hydration/dehydration of laumontite decreased slake durability of the rock; the SDI decreased approximately linearly as laumontite content increased.

scholarly journals Investigations on Engineering Properties of Solidified/Stabilized Pb-Contaminated Soil Based on Alkaline Residue

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Fusheng Zha ◽  
Dongdong Pan ◽  
Long Xu ◽  
Bo Kang ◽  
Chengbin Yang ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Contaminated Soil ◽  
Microstructural Analysis ◽  
Engineering Properties ◽  
Contaminated Sites ◽  
Adsorptive Capacity ◽  
Curing Time ◽  
Test Results ◽  
Hydration Products ◽  
Microstructure Characteristics

Solidification/stabilization (S/S) has been considered as one of the most effective techniques for remediation of the heavy metal-contaminated sites. Among various binders adopted in S/S, alkaline residue (AR) could be considered as a new binder to treat heavy metal-contaminated soil due to its strong adsorptive capacity for heavy metal ions. So in this paper, the strength, leaching, and microstructure characteristics of the solidified/stabilized Pb-contaminated soil by using alkaline residue are systematically investigated. Test results present that the unconfined compressive strength (UCS) of the treated soil will increase, while the leached Pb2+ concentration will decrease, with the increase of the alkaline residue content in the specimen. The UCS increases significantly with the curing time increasing during the initial 28 days, after which the UCS of the specimen becomes stable. The leached Pb2+ concentration decreases significantly at the initial 28 days followed by a stable trend with curing time increasing. The UCS decreases and the leached Pb2+ concentration increases with the increase of the initial Pb2+ concentration in the specimen. The microstructural analysis performed by scanning electron microscope (SEM) showed that the increase of the alkaline residue content and curing time will result in more hydration products and densified microstructure, which could effectively improve the engineering properties of the specimen.

scholarly journals Impact of a Structure on Durability of Modified Nickel-Base Superalloys in Creep Conditions/ Wpływ Struktury Na Trwałość W Warunkach Pełzania Modyfikowanych Nadstopów Na Bazie Niklu

2014 ◽  
Vol 59 (4) ◽  
pp. 1559-1563 ◽  
Author(s):  
M. Ciesla ◽  
M. Manka ◽  
P. Gradon ◽  
F. Binczyk
Keyword(s):  
Creep Resistance ◽  
Morphological Structure ◽  
Aircraft Engine ◽  
Coarse Grained ◽  
Test Results ◽  
Cast State ◽  
Accelerated Creep ◽  
Nickel Base ◽  
The Impact ◽  
Modification Treatment

Abstract The study assesses the impact of surface and bulk modification and filtration during pouring on a durability under accelerated creep conditions of casts made of IN-713C and MAR-247 nickel superalloys scrap used for manufacturing of aircraft engine parts. The impact of solutionizing (1185°C/2 h) with subsequent ageing (870°C/20 h) on the creep resistance of a casting made from MAR-247 coarse-grained superalloy was also examined. Morphological structure parameters were determined with the use of Met-Ilo software. Macrostructure analysis of casts showed very significant impact of surface modification treatment. Creep test results clearly showed that coarse grained samples of IN-713C and MAR-247 superalloys have higher creep resistance. Moreover alloy MAR-247 had higher creep durability after heat treatment compared to as-cast state.

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