Influence of Polyurethane Polymer on the Strength and Mechanical Behavior of Sand-root Composite

Jin Liu,Zhihao Chen,Zhaojun Zeng,Debi Prasanna Kanungo,Fan Bu,Yuxia Bai,Changqing Qi,Wei Qian 한국섬유공학회 2020 Fibers and polymers Vol.21 No.4

Vegetation has good application in slope stabilization, but its beneficial effects on reinforcing topsoil are generallylimited by the soil properties it was cultivated in. This study aims at evaluating the strength improvements of sand-rootcomposite by treating with polyurethane polymer and hence investigating the mechanism of polymer-root-soil interactions. Vegetation roots were selected and mixed with dry sand and polymer solution to prepare remolded specimens. A series ofexperimental tests were then performed at different percentages of root content (0, 0.4, 0.8, 1.2, and 1.6 % by weight of drysand) and polymer content (1, 2, and 4 % by weight of dry sand) to evaluate the shear parameters and unconfinedcompressive strength (UCS). The combined mechanism was studied by scanning electron microscopy (SEM) images. Theresults showed that the strengthening effect has greater efficiency with higher polymer content. Through varying contents ofvegetation root, it was found that low root content induced an undesirable weakening effect on the strength of the treated soil. However, this situation was somewhat improved with the increase in root content. The good flexibility of polymers not onlypromote the capacity of soil to energy absorption, but also impart good ductility to soil. The presence of polymers greatlystrengthens soil stability due to its special network structure, by which the improved shear resistance at the root-soil interfaceprovides sufficient anchorage effect for the tensile strength of roots to be fully mobilized. Overall, the synergistic effect ofroot reinforcement and polymer treatment has the potential for its use in soil stabilization.

식생뿌리의 전단강도 보강에 의한 사면안전율 해석 -잣나무 뿌리를 중심으로-

조주형,이종성 한국조경학회 2000 韓國造景學會誌 Vol.27 No.5

This study measured the shearing resistance of the roots of the Pinus Koraiensis by the tensile strength gained through their individual tensile test for the Root Reinforcement Model. On the basis of the shearing resistance value calculated through such a process the factor of safety(Fs) was comparatively presented by using the simplified Janbu Method in PCSTABL5M, the slop-analyzing software which had been developed in Purdue University of the U.S.A according to the shape of a slope and the type of soil. The results to have measured a stress and the factor of safety(Fs) by experiment are as follows. 1) The mean root diameter of the Pinus Koraiensis used for this experiment was 2.483mm and the mean tensile stress was calculated as 422.846(kgf/$\textrm{cm}^2$). In the strain ratio of material and the elastic modulus was measured 7.8%, 9,291.92(kgf/$\textrm{cm}^2$). 2) The shearing strength including the resistance of soil and root is expressed as Rt=C+Cr+$\sigma$.tan . ΔCr(kg/$\textrm{cm}^2$) of the shearing resistance calculated by estimating the areal ratio of roots at 10 is 0.253(kgf/$\textrm{cm}^2$). 3) As the result of making an analysis of the natural slope stability by the soil parameter, the factor of safety(Fs) was calculated at 1.795 in CL, and the stability analysis of the root reinforcement slope, Fs was calculated at 1.952. However, since a precise analysis of the controlled factors of the slope analyses are demanded for more accurate dynamic analyses, the future demands a study on this.

Fiber-reinforced composite resin bridges: an alternative method to treat root-fractured teeth

Heo, Gun,Lee, Eun-Hye,Kim, Jin-Woo,Cho, Kyung-Mo,Park, Se-Hee The Korean Academy of Conservative Dentistry 2020 Restorative Dentistry & Endodontics Vol.45 No.1

The replacement of missing teeth, especially in the anterior region, is an essential part of dental practice. Fiber-reinforced composite resin bridges are a conservative alternative to conventional fixed dental prostheses or implants. It is a minimally invasive, reversible technique that can be completed in a single visit. The two cases presented herein exemplify the treatment of root-fractured anterior teeth with a natural pontic immediately after extraction.

Push-out bond strengths of fiber-reinforced composite posts with various resin cements according to the root level

Kyung-San Min,Yoon Lee,Ji-Myung Bae,Young-Sin Noh,Hoon-Sang Chang 대한치과보철학회 2013 The Journal of Advanced Prosthodontics Vol.5 No.3

PURPOSE The aim of this study was to determine whether the push-out bond strengths between the radicular dentin and fiber reinforced-composite (FRC) posts with various resin cements decreased or not, according to the coronal, middle or apical level of the root. MATERIALS AND METHODS FRC posts were cemented with one of five resin cement groups (RelyX Unicem: Uni, Contax with activator & LuxaCore-Dual: LuA, Contax & LuxaCore-Dual: Lu, Panavia F 2.0: PA, Super-Bond C&B: SB) into extracted human mandibular premolars. The roots were sliced into discs at the coronal, middle and apical levels. Push-out bond strength tests were performed with a universal testing machine at a crosshead speed of 0.5 mm/min, and the failure aspect was analyzed. RESULTS There were no significant differences (P>.05) in the bond strengths of the different resin cements at the coronal level, but there were significant differences in the bond strengths at the middle and apical levels (P<.05). Only the Uni and LuA cements did not show any significant decrease in their bond strengths at all the root levels (P>.05); all other groups had a significant decrease in bond strength at the middle or apical level (P<.05). The failure aspect was dominantly cohesive at the coronal level of all resin cements (P<.05), whereas it was dominantly adhesive at the apical level. CONCLUSION All resin cement groups showed decreases in bond strengths at the middle or apical level except LuA and Uni.

Fiber-reinforced composite resin bridges: an alternative method to treat root-fractured teeth

Gun Heo,Eun-Hye Lee,Jin Woo Kim,Kyung-Mo Cho,Se-Hee Park 대한치과보존학회 2020 Restorative Dentistry & Endodontics Vol.45 No.1

The replacement of missing teeth, especially in the anterior region, is an essential part of dental practice. Fiber-reinforced composite resin bridges are a conservative alternative to conventional fixed dental prostheses or implants. It is a minimally invasive, reversible technique that can be completed in a single visit. The two cases presented herein exemplify the treatment of root-fractured anterior teeth with a natural pontic immediately after extraction.

Push-out bond strengths of fiber-reinforced composite posts with various resin cements according to the root level

Chang, Hoon-Sang,Noh, Young-Sin,Lee, Yoon,Min, Kyung-San,Bae, Ji-Myung The Korean Academy of Prosthodonitics 2013 The Journal of Advanced Prosthodontics Vol.5 No.3

PURPOSE. The aim of this study was to determine whether the push-out bond strengths between the radicular dentin and fiber reinforced-composite (FRC) posts with various resin cements decreased or not, according to the coronal, middle or apical level of the root. MATERIALS AND METHODS. FRC posts were cemented with one of five resin cement groups (RelyX Unicem: Uni, Contax with activator & LuxaCore-Dual: LuA, Contax & LuxaCore-Dual: Lu, Panavia F 2.0: PA, Super-Bond C&B: SB) into extracted human mandibular premolars. The roots were sliced into discs at the coronal, middle and apical levels. Push-out bond strength tests were performed with a universal testing machine at a crosshead speed of 0.5 mm/min, and the failure aspect was analyzed. RESULTS. There were no significant differences (P>.05) in the bond strengths of the different resin cements at the coronal level, but there were significant differences in the bond strengths at the middle and apical levels (P<.05). Only the Uni and LuA cements did not show any significant decrease in their bond strengths at all the root levels (P>.05); all other groups had a significant decrease in bond strength at the middle or apical level (P<.05). The failure aspect was dominantly cohesive at the coronal level of all resin cements (P<.05), whereas it was dominantly adhesive at the apical level. CONCLUSION. All resin cement groups showed decreases in bond strengths at the middle or apical level except LuA and Uni.

Push-out bond strengths of fiber-reinforced composite posts with various resin cements according to the root level

장훈상,노영신,이윤,민경산,배지명 대한치과보철학회 2013 The Journal of Advanced Prosthodontics Vol.5 No.3

PURPOSE. The aim of this study was to determine whether the push-out bond strengths between the radicular dentin and fiber reinforced-composite (FRC) posts with various resin cements decreased or not, according to the coronal, middle or apical level of the root. MATERIALS AND METHODS. FRC posts were cemented with one of five resin cement groups (RelyX Unicem: Uni, Contax with activator & LuxaCore-Dual: LuA, Contax & LuxaCore-Dual: Lu, Panavia F 2.0: PA, Super-Bond C&B: SB) into extracted human mandibular premolars. The roots were sliced into discs at the coronal, middle and apical levels. Push-out bond strength tests were performed with a universal testing machine at a crosshead speed of 0.5 mm/min, and the failure aspect was analyzed. RESULTS. There were no significant differences (P>.05) in the bond strengths of the different resin cements at the coronal level, but there were significant differences in the bond strengths at the middle and apical levels (P<.05). Only the Uni and LuA cements did not show any significant decrease in their bond strengths at all the root levels (P>.05); all other groups had a significant decrease in bond strength at the middle or apical level (P<.05). The failure aspect was dominantly cohesive at the coronal level of all resin cements (P<.05), whereas it was dominantly adhesive at the apical level. CONCLUSION. All resin cement groups showed decreases in bond strengths at the middle or apical level except LuA and Uni.

뿌리의 공간분포를 고려한 수목 뿌리의 토양보강 효과에 대한 분석

김동엽 ( Dong Yeob Kim ),이상호 ( Sang Ho Lee ),임상준 ( Sang Jun Im ) 한국환경복원기술학회(구 한국환경복원녹화기술학회) 2011 한국환경복원기술학회지 Vol.14 No.4

Tree roots can enhance soil shear strength and slope stability. However, there has been a limited study about root reinforcement of major tree species in Korea because of some experimental difficulties. Thus, this study was conducted to analyze the performance of Japanese larch ( Larix kaempferi) and Korean pine ( Pinus koraiensis) which are two common plantation species in Korea. Profile wall method was used to measure the spatial distribution of root system and its diameter within 15 soil walls of Japanese larch stand and 13 soil walls of Korean pine stand in Taehwa University Forest, Seoul National University, Korea. Root tensile properties of each species were assessed in the laboratory, and root reinforcements were estimated by Wu model. The study observed that the number and cross-sectional area (CSA) of root in both species could tend to decrease with soil depth. Especially, CSA were well-fitted to exponential functions of soil depth. Mean root area ratios (RAR) were 0.03% and 0.10% for Japanese larch and Korean pine, respectively. Estimated root reinforcement from Wu model were, on the average, 4.04 kPa for Japanese larch and 12.26 kPa for Korean pine. Overall, it was concluded that root reinforcement increased the factor of safety (Fs) of slope for small-scale landslide as the result of two-dimensional (2-D) infinite slope stability analysis considering vegetation effects.

비탈면 안정을 위한 참싸리 뿌리의 토양보강 효과

황진성,지병윤,오재헌,차두송 강원대학교 산림과학연구소 2014 Journal of Forest Science Vol.30 No.1

To examine the soil reinforcement by the shrub with shallow root systems for slope stability, we developed insitu apparatus for direct shear test and conducted the insitu field tests for Lespedeza cyrtobotrya, a representative revegetation species for artificial hillslopes. The insitu field tests were conducted for two different soil conditions (the rooted soils and non-rooted soils) and we then compared the experimental values with those calculated from the Wu model. The results showed that the soil reinforcement derived from the insitu field tests ranged from 0.01525 to 0.1438 kgf/cm2 while the one calculated from the Wu model ranged from 0.1952 to 0.2696 kgf/cm2 . Our finding suggests more field tests are needed to collect the related parameters in the model application thereby predicting the reliable soil reinforcement by the shrub root systems.

Modeling the contribution of trees to shallow landslide development in a steep, forested watershed

Kim, D.,Im, S.,Lee, C.,Woo, C. Elsevier Science 2013 Ecological engineering Vol.61 No.3

The objective of this study was to identify the contribution of trees to shallow landslide development in a steep forested watershed using a deterministic modeling approach. Rainfall interception, tree root reinforcement, and tree surcharge were considered the main factors. A revised version of the Transient Rainfall Infiltration and Grid-based Regional Slope-stability (TRIGRS) model was employed in the approach. Hydrological modifications included adding the processes of rainfall interception using an application of the Rutter model. The revised infinite slope stability model was also used to consider tree root reinforcement and tree surcharge. A comparative analysis was conducted with the results simulated by TRIGRS and the revised model to quantify the contribution of trees to landslide development. The Bonghwa site in South Korea, which was damaged by an extreme storm with 228mm of rainfall on July 24-25, 2008, was selected as the study site. Data related to the local topography, soil, and forest properties were measured in the field for use in the model simulations, although some data were taken from the literature or assumed by the authors on the basis of the site characteristics. The results showed the rainfall interception did not significantly affect the amount of rainfall reaching the soil surface, but it changed the temporal distribution of the rainfall intensity. Additionally, the rainfall interception was found to have little influence on infiltration from the simulation results of pore water pressure. The results of the simulated factor of safety indicated that root reinforcement and tree surcharge made significant contributions to the enhancement of slope stability. The simulation results were compared to the results from locations in which landslides occurred, indicating that the revised model estimated the landslide susceptibility over the entire study site well, while TRIGRS appeared to overestimate the risk of shallow landslides. In conclusion, trees appeared to make a significant mechanical contribution to shallow landslide development during a severe storm event in steep, forested watersheds. Efforts to revise the existing model improved its performance to assess the shallow landslide susceptibility of mountainous watersheds despite some limitations of the current study.