Compaction Roller Research Articles

플라이애쉬와 리젝트애쉬를 활용한 섬유보강 빈배합 콘크리트의 강도 특성 및 롤러다짐을 활용한 현장적용 실험

Road pavements in Korea generally show shorter service life than the predicted one. There are many reasons for this phenomenon including increased traffic load and other attacks from exposure conditions. In order to extend a service life and upgrade the pavement, a new multi-functional composite pavement system is being developed in Korea. This study is to investigate the performances of fiber-reinforced lean concrete for pavement base. This study considered mineral admixtures of fly ash and reject ash. The reject ash is defined as ash that does not meet the specifications for fly ash so that it cannot be used as a supplemental material for cement replacement. Due to the inherent property of lean concrete, compaction during the fabrication of specimens is a key factor. Therefore, this study suggests an appropriate compaction method. From the test results, the compressive strengths of the concrete satisfied the required limit of 5 MPa at 7 days. When a compaction roller was used to mimic actual field conditions, the strength development seemed to be influenced by the compaction energy rather than hydration of cement itself.

Design of Mould on Cold Rolling for CARB Bearing’s Arc Roller

CARB bearing is a kind of compact aligning roller bearing with internal contact and slightly curved surface, which is the most important breakthrough of bearing technology in rencent 50 years. CARB bearing’s special structural design make it has unique advantages, for example, reducing the mechanical structure size, reducing cost, extending bearing life, reducing noise, improving radial load capacity and high temperature stability, etc, so it is widely used in the manufacturing industry. CARB bearing’s roller is cylinder with arc, this unique structure is suitable for adopting cold rolling technology

Development and Evaluation of Relative Compaction Specifications Using Roller-Based Measurements

AbstractEarthwork quality control/quality assurance specifications are currently being developed and implemented with continuous compaction control (CCC) and intelligent compaction (IC) rollers. This paper presents and explores two methods of using CCC/IC data based on a relative compaction approach. The first method examines the relative change in roller-measured mean compaction level between passes while the second method examines relative changes spatially. The relative compaction methods were implemented on a test site. The relative compaction methods were found to provide improvement over current methods due to their ability to quantitatively assess 100% of the compacted area while decreasing time and cost during the construction process.

Spatial analysis of modern soil compaction roller measurement values

Modern compaction rollers monitor soil properties by observing vibrational characteristics of the soil. A vibrating drum traverses the compaction site measuring soil stiffness and collecting GPS coordinates that are together termed roller measurement values (RMVs). These RMVs can be modeled as a random spatial field and additively decomposed into any sensible combination of mean terms, spatial terms, spline terms, and ridge regression terms. The goal of this modeling is to implement intelligent compaction for quality control and quality assurance purposes. Proper modeling of such data (stationarity, anisotropy,.) is then of paramount concern. Each layer of the compaction site can be modeled by the n-vector y = Xβ+α+γ+ ɛ, where Xβ is a low-order (linear) polynomial trend, α is a mean term estimated using ridge regression or splines modeling the large-scale variation, γ is a (zero-mean Gaussian) spatial process modeling the small-scale variation, and ɛ is the noise. Here, X is the (n × p) design matrix with rank p. There are many general approaches to working with such an additive mixed model, including a backfitting procedure for maximum-likelihood estimation and generalized cross-validation. Due to computational complexity of maximum-likelihood estimation a backfitting procedure, Furrer and Sain (2009) [1], was extended to the more general models used here and employed in the estimation. The extended backfitting procedure has been shown to converge and the iterative least-squares estimates have been shown to converge to the generalized least-squares estimate. A simulation study has been conducted to analyze estimates of this general model using a penalized likelihood and generalized cross-validation (GCV) approach as well. Results of the cross-validation study using a spline structure indicate there are some random fields that can be generated that do not have a minimum GCV.

Soil Stiffness Evaluation for Compaction Control of Cohesionless Embankments

Abstract Mechanistic pavement design procedures based on elastic layer theory require characterization of pavement layer materials including subgrade soil. This paper discusses the subgrade stiffness measurements obtained from a new compaction roller for compaction control on highway embankment projects in Kansas. Three test sections were compacted using a single, smooth steel drum intelligent compaction (IC) roller that compacts and simultaneously, measures stiffness values of the compacted soil. Traditional compaction control measurements such as, density, in-situ moisture content, stiffness measurements using a soil stiffness gage, surface deflection tests using the light falling weight deflectometer (LFWD) and falling weight deflectometer (FWD), and penetration tests using a dynamic cone penetrometer (DCP), were also done. The results show that the IC roller was able to identify the locations of lower soil stiffness in the spatial direction. Thus, an IC roller can be used in proof rolling. IC roller stiffness showed sensitivity to the field moisture content indicating that moisture control during compaction is critical. No universal correlation was observed among the IC roller stiffness, soil gage stiffness, back-calculated subgrade moduli from the LFWD and FWD deflection data, and the California bearing ratio obtained from DCP tests. The discrepancy seems to arise from the fact that different pieces of equipment were capturing response from different volumes of soil on the same test section.

Моделирование заделки корней саженцев катками при посадке леса

Моделирование заделки корней саженцев катками при посадке леса

Subgrade Design Parameters from Samples Prepared with Different Compaction Methods

The standard and modified Proctor compaction tests have been widely used for evaluation of design properties and compaction characteristics of subgrade soils. However, different types of compaction roller equipment, each producing a different level of soil compaction, are used in the field for compaction of subgrade soils. The purpose of this paper is to evaluate the design properties of compacted subgrade soils using the gyratory compactor made by Servopac to simulate field compaction conditions. Field compaction data were collected from a road construction site in Pusan, Korea. After compaction of the subgrade soil in the field using a vibratory roller was concluded, block samples of the subgrade material were collected. Disturbed soil samples were collected for preparation of specimens in the laboratory using the Proctor compaction and gyratory compaction methods. Unconfined compression test results show that the peak strength, cohesion, and elastic modulus values of the specimens prepared from the field block samples and that of the specimens prepared using the Superpave gyratory compactor with a 600kPa vertical pressure are similar. On the other hand, much higher values were obtained for these quantities for the laboratory specimens prepared using the modified Proctor method. Our test results indicate that the evaluation of design properties of subgrade soils based solely on the Proctor compaction tests may not be appropriate.

The use of recycled tire chips to minimize dynamic earth pressure during compaction of backfill

The backfill areas of concrete culverts constructed in roads have been subjected to differential settlement due to poorly compacted soils. Dynamic compaction rollers cannot be fully utilized to compact the backfill soils near the culverts because the high earth pressure induced by dynamic loading frequently results in cracks in the culvert walls. In this study, two cushion materials, recycled tire chips and expanded polystyrene (EPS) boards are applied on the culvert walls in backfill areas to reduce the dynamic earth pressure induced by the compaction loading as well as to improve the characteristics of compacted soils. A numerical analysis is carried out to study the effects of the cushion materials on the stress variation with soil depth in the backfill areas. The numerical analysis shows that a cushion material with low elastic modulus and high damping ratio can effectively reduce the dynamic earth pressure. Field tests are also performed to study the performance of the two cushion materials. It is found from the field tests that the both cushion materials reduce the dynamic earth pressure acting on the culvert wall. However, the recycled tire chips are more efficient in reducing the dynamic earth pressure because of its relatively high damping ratio and low stiffness values compared to the EPS.

A Weed Compaction Roller System for Use with Mechanical Herbicide Application

Abstract We designed, constructed, and field-tested a versatile and unique weed compaction roller system that can be used with mechanical herbicide application for invasive weed control in tree plantations, agronomic settings, and areas where localized flora and fauna are in danger of elimination from the landscape. The weed compaction roller system combined with herbicide application generally had greater vegetation control compared with using only herbicide treatments or the unsprayed control. The roller system-herbicide treatment combination showed substantial total vegetation control two growing seasons after application without impacting diameter growth of the crop trees, which supports the need for less frequent entries into the field. The cost of the roller system was approximately $300.00.

Costs of supply chains of Miscanthus giganteus

Miscanthus is a perennial C 4-grass of East Asian origin that can have a future as an agricultural crop, producing raw material for energy, building materials and geotextiles. The costs of plant establishment, production, harvest, storage and transport have been investigated as components in various chains of primary production of miscanthus to compare those chains and to calculate the price for which the processing industry could buy the crop if it would be introduced in the north-east provinces of the Netherlands. All parameters concerning contractor costs, transport distances, crop rotation and best farming practice have been chosen according to the up-to-date situation of this area. Three possible scenarios were investigated on the basis of farm labour input and the use of the margin in the cost calculation. Costs for eight different chains were compared from soil preparation until transport to the processing plant. Planting was evaluated with plantlets and rhizomes. For harvesting, existing choppers and balers were chosen, in addition to prototypes for a compact roller and whole stem harvester. To reduce transport cost of chopped material, an adapted recycling paper compacting machine was included in the calculations. With regard to transport, different systems were analysed and some calculation on costs, correlated to transport distances, were carried out. Drying costs are not included in the calculations since they depend too much on the variable weather conditions. It was concluded that costs of chopped and baled products do not differ much for the farmers scenario. Chopped product is cheapest when production is performed by the Miscanthus company. Costs then are 126 ECU/ton. Storage and transport costs are lowest when density of the product is high, so compact rolled and compacted materials are cheapest for larger transport distances. The whole stem harvester should have a higher capacity than assumed to further decrease costs. This harvest method however also offers a long harvest period without drying costs.

Thermoviscoelastic Analysis of the Thermoplastic Composite Tape Placement Process

The thermomechanical behavior of a thermoplastic composite laminate during the tape placement process has been studied. Stresses induced by the compaction roller are predicted using a finite element method. These stresses control the compaction and bonding behavior of the laminate. In the analysis, the tape placement process is considered as a quasi-steady state rolling contact problem. The effect of temperature on creep compliance is included by treating the composite as a thermorheologicaliy simple material. Thermal expansion coefficients are allowed to be temperature dependent. The effect of friction at the contact surface is also taken into account. The numerical results show how the process parameters (e.g., roller velocity, roller pressure, heat input) are related to temperature and stress distributions within the composite. These relationships can be used to predict the bonding behavior of the laminate.

A study on heat transfer during thermoplastic composite tape lay-up process

A study on heat transfer during thermoplastic composite tape lay-up process was done. To investigate the relation between major process variables, experiments as well as numerical simulations were performed. A small-scale tape lay-up system was built. A hot nitrogen torch was used to heat the prepreg tape. Right after the torch, a compaction roller was located to bond the prepreg plies. Temperatures inside the composite at four different locations through the thickness were measured, using thermocouples. Experiments were done for different process conditions. Numerical simulations also were performed, using the finite element code developed in this study. A numerical code was run for the same conditions as the experiment. Close agreement was observed between the numerical results and the experimental data.

On‐line consolidation of thermoplastic towpreg composites in filament winding

AbstractA study of the use of thermoplastic powder coated towpregs in filament winding was conducted. A suitable technique for manufacturing parts with adequate on‐line consolidation was identified through an experimental investigation that compared several techniques. This process utilized a single compaction roller on‐line consolidation head with hot air guns to obtain consolidation at the lay‐down point on the mandrel. The addition of a heated pultrusion die between the creel system and the filament winder was found to produce the best process. Nylon 11/E‐glass towpreg was used in this study. The effect of winding speed and compaction force on the quality of the resulting parts was determined in order to optimize the process. Only the speed was found to have a significant effect, with better quality parts being made at higher speed. Observations were also made on parts manufactured with polypropylene and E‐glass towpreg, as well as on parts wound with helical patterns.