A study on performance of roller-compacted concrete for pavement

Chhorn, Chamroeun,Hong, Seong Jae,Lee, Seung-Woo Elsevier 2017 Construction and Building Materials Vol.153 No.-

<P><B>Abstract</B></P> <P>In this study, field test investigation is conducted on roller-compacted concrete pavement (RCCP). A total of five sections of RCCP were constructed in Seokcho of South Korea for this test. Vebe time, a represented parameter of consistency, is employed as quality control parameter for RCC mixture. Performance related properties and surface properties of each section were investigated and correlated to the quality control parameter. Based on the findings from previous researches and results from this field performance investigation, some recommendations for improving mixture design of RCC are suggested.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The performance of roller-compacted concrete pavement (RCCP) is investigated. </LI> <LI> The evaluation of mixture design of RCCP is conducted. </LI> <LI> Recommended range of consistency is suggested for RCCP. </LI> </UL> </P>

Field Evaluation on Acoustic Performance of Exposed Aggregate Concrete Pavement

Chhorn Chamroeun,Han Seung Hwan,Park Jun Young 대한토목학회 2020 대한토목학회 학술대회 Vol.2020 No.10

Parametric Study on Buckling Resistance of the Thin BFRP (Basalt Fiber Reinforced Polymer) Plate Subjected to Combined Loading

Chhorn, Buntheng,정우영 한국복합신소재구조학회 2019 복합신소재구조학회논문집 Vol.10 No.1

The buckling behavior of thin basalt fiber reinforced polymer (BFRP) plate subjected to combined loading was evaluated with numerical approach by using the finite element method (FEM). Multiple parameters were studied, such as, boundary conditions, aspect ratio of plate dimension and loading condition. Mechanical properties of BFRP was based on the experiment of tensile and in-plane shear test, by using domestically fabricated sample. The classical plate theory was utilized to analyze symmetrical laminate composite plate in this study. For the cases of biaxial, combined biaxial and shear loading, it was found that when the aspect ratio was between 0.5 to 1.0, the non-dimensional buckling load decreased quickly. Conversely, it decreased slightly, when aspect ratio was between 1.0 to 2.5. Furthermore, it was found that the adding in-plane shear loading to existing axial loading, it could be seen that the decrement in non-dimensional buckling load is minuscule, about 4%.

Relationship between flexural or splitting tensile strength and compressive strength of roller-compacted concrete

Chhorn Chamroeun,Han Seung Hwan,Chon Beom Jun,Lee Seung Woo 한국도로학회 2015 한국도로학회 학술발표회 논문집 Vol.2015 No.10

More Roller-compacted concrete (RCC) is a dry concrete consisted of same materials as conventional concrete with different proportioning which requires compaction effort in order to reach its final form. Thus, both hydration and aggregate interlock play important roles in its strength augmentation. Flexural strength, an important factor in pavement design and fatigue cracking resistance, can be difficult to be obtained at in-situ and may be subjected to high variability. Even though its compressive strength is relatively high compared to conventional concrete with similar binder content, the relationship between compressive strength and flexural or tensile strength were not well defined. The goal of this research is to compare the relationship between compressive strength and flexural strength as well as the relationship between compressive strength and splitting tensile strength of RCC with those of conventional concrete using various equations suggested in other researches and also to determine new regression equations for estimating RCC’s flexural and splitting tensile strength. The positive result of RCC’s flexural strength was found; it was higher than majority of predicted values from conventional concrete for the same compressive strength. In contrast, RCC’s splitting tensile strength was relatively low compared to that of conventional concrete for the same compressive strength. Power equations were learned to be suitable for relationship between compressive and flexural strengths as well as relationship between compressive and splitting tensile strengths.

A Fundamental Study on Flexural-Fatigue Performance of Basalt Fiber Reinforced Polymer Composite

( Chhorn Buntheng ),정우영 ( Jung Wooyoung ) 한국복합신소재구조학회 2020 복합신소재구조학회논문집 Vol.11 No.6

복합재료의 구조물 활용에 있어 동적하중에 의한 재료성능에 대한 영향성은 빈번하게 발생할 수 있다. 이들 동적하중들 중 피로하중은 실제적으로 복합재료 구조 또는 부재의 손상이나 파괴를 야기하는 주요 원인이 된다. 본 연구의 일차적인 목표는 이들 복합재료의 휨 피로 성능을 조사할 수 있는 장비 개발이며 두 번째 목표로는 이들 장비를 활용, 바잘트 복합재료에 대한 휨-피로성능에 대한 초기 연구를 수행하는 것이다. 이를 위하여 진공압출공법을 활용, 평균 두께 4.0mm의 바잘트 섬유보강 플레이트를 제작하였다. 총 5개의 휨-피로 시편들이 제작되었으며 각 시편들은 반복응력 비 Smin/Smax = 1의 크기로 각 시편에 작용하였다. 이때 초기 응력레벨은 122.24MPa로 고려되었으며 재료의 파괴 한계상태를 국외자료를 토대로 초기 강성 대비 20% 강성 감소로 고려하였다. 최종적으로 본 연구를 통하여 총 3단계 구간들에서 강성값의 감소 변화를 확인할 수 있었다. 첫 번째 구간에서는 대체적으로 높은 강성 감소가 시험체에서 발생하였으며 이후 두 번째 구간에서도 지속적인 강성값 감소가 확인되었다. 최종적으로 3단계 구간에서 복합재료 내 섬유 파단과 더불어 복합재료 전체에 대한 한계파괴상태에 도달하였다. Throughout their service life, composites are commonly subjected to dynamic loading. Fatigue is a type of loading that widely induces failure in composite components. Therefore, the first objective of this study was to develop a machine to test the flexural-fatigue performance of composites. The second objective was to investigate the flexural-fatigue performance of basalt fiber reinforced polymer. The vacuum infusion technique was used to manufacture laminates with an average thickness of 4.0mm. Five flexural-fatigue specimens were conducted at a cyclic stress ratio of Smin/Smax = 1. An initial stress level of 122.24MPa was used. A 20% reduction in stiffness indicated failure. The results illustrate that the component life of composite materials consists of three stages of stiffness degradation. In the first stage, a high rate of stiffness degradation occurs. In the second stage, moderate stiffness degradation occurs, which showed a large portion of component life of composite materialssecond. In the third stage, more significant types of damage, like fiber fracture, occur and cause the material to fail completely.

Workability Improvement of Roller-Compacted Concrete Pavement

Chhorn Chamroeun,Han Seung Hwan,Chon Beom Jun,Lee Seung Woo 한국도로학회 2016 한국도로학회 학술발표회 논문집 Vol.2016 No.06

Roller-compacted concrete or RCC is a dry concrete that requires compaction in order to reach its final form. Its consistency is usually overlooked due to its inconsistency and lack of subjective nature. To work with this concrete, however, appropriate consistency is required for supporting the compacting machine and minimizing compaction energy. Due to transportation and compaction time, maintaining proper consistency within a period of time is also necessary. Vebe time, a represent parameter of dry concrete consistency, ranged from 30 to 75 seconds is considered appropriate for RCC in pavement application. The purpose of this study is to improve workability of this concrete which consisted of improving its consistency and maintaining it within the working time. It was confirmed that the workable time of a normal RCC is less than one hour. Moreover, it was found that Vebe time drops when water content increases and goes up when sand by aggregate ratio increases. Various admixtures were also employed in this study in order to improve the workability of this concrete. Poly Naphtalene Sulfonate superplasticizer, particularly, was found to be the most effective in term of lowering down Vebe time and maintaining it. With just 0.3% of this admixture, the working time of RCC can be extended up to four hours without affecting its compressive strength.

A Study on Effect of Surface Retarders and Exposure Time on Exposed Aggregate Concrete

Chhorn Chamroeun,Han Seung Hwan,Park Jun Young 한국도로학회 2021 한국도로학회 학술대회 발표논문 초록집 Vol.2021 No.03

A Study on the Interference Avoidance Using Control Information in LTE Femtocell Systems

Sok Chhorn,Se-Jin Kim,Si-O Seo,Seung-Wan Ryu,Hyong-Woo Lee,Choong-Ho Cho 한국통신학회 2011 한국통신학회 학술대회논문집 Vol.2011 No.2

The Three-year Effect of Thinning Intensity on Biomass in Larix kaempferi and Pinus koraiensis Plantation

Vireak Chhorn,Yeongwan Seo,Daesung Lee,Jungkee Choi 강원대학교 산림과학연구소 2020 Journal of Forest Science Vol. No.

This study aimed to figure out and compare the increment of biomass by thinning intensity focused on the plantation of the two major coniferous species (Larix kaempferi and Pinus koraiensis) of South Korea. The inventory interval was three years under the effects of three types of thinning treatments; control (no thinning), light (20% thinning) and heavy (40% thinning). The results showed standing biomass increment of both species decreased as thinning intensity increased (heavy<light<control). Biomass increment of each tree compartment (roots, stem, branches and foliage) also followed the increment pattern of the total biomass. In contrast, the rate of biomass growth increased as increasing thinning intensity (heavy>light>control). Meanwhile, the lowest of on-site biomass changes occurred in the control plot, and the greatest was in the heavy thinning plot because thinning was involved with leaving the felling residual biomass (leaves, branches and roots) on the site. According to the results from this short-term study, unthinned stands is preferable for maximizing standing biomass as well as carbon sequestration. However long-term investigation should be considered in order to see more clear results.

Spectrum Reuse Schemes with Power Control for Device-to-Device Communication in LTE-Advanced Cellular Network

( Sok Chhorn ),( Seok-ho Yoon ),( Si-o Seo ),( Seung-yeon Kim ),( Choong-ho Cho ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.12

The spectral efficiency of cellular networks can be improved when proximate users engage in device-to-device (D2D) communications to communicate directly without going through a base station. However, D2D communications that are not properly designed may generate interference with existing cellular networks. In this paper, we study resource allocation and power control to minimize the probability of an outage and maximize the overall network throughput. We investigate three power control-based schemes: the Partial Co-channel based Overlap Resource Power Control (PC.OVER), Fractional Frequency Reuse based Overlap Resource Power Control (FFR.OVER) and Fractional Frequency Reuse based Adaptive Power Control (FFR.APC) and also compare their performance. In PC.OVER, a certain portion of the total bandwidth is dedicated to the D2D. The FFR.OVER and FFR.APC schemes combine the FFR techniques and the power control mechanism. In FFR, the entire frequency band is partitioned into two parts, including a central and edge sub-bands. Macrocell users (mUEs) transmit using uniform power in the inner and outer regions of the cell, and in all three schemes, the D2D receivers (D2DRs) transmit with low power when more than one D2DRs share a resource block (RB) with the macrocells. For PC.OVER and FFR.OVER, the power of the D2DRs is reduced to its minimum, and for the FFR.APC scheme, the transmission power of the D2DRs is iteratively adjusted to satisfy the signal to interference ratio (SIR) threshold. The three schemes exhibit a significant improvement in the overall system capacity as well as in the probability of a user outage when compared to a conventional scheme.