Open-graded Aggregate Research Articles

Evaluation of porous asphalt mixtures stabilized by human scalp hair

Porous asphalt (PA) is an open-graded hot mixed asphalt that presents improved surface drainage during rainfall, improving road safety in wet weather and preventing rainfall water from receding in closed areas. The main challenge facing PA paving is binder draindown during mix transportation and placement due to the confluence of low fillers cases, open-graded aggregate gradation, and high asphalt contents. Mineral fibers such as slag wool (SW), despite their negative effects on human health and the environment, have been used as stabilizers in PA mixtures to increase binder retention and avoid stability reduction. This study evaluates using human scalp hair (HSH) as an alternative stabilizing fiber to SW in PA mixtures. Using HSH in PA mixtures is a sustainable waste recycling method and an economical solution to enhance the binder retention and stability of PA mixtures. The performance of the PA mixtures that stabilized with SW (control) and HSH was compared with National Asphalt Pavement Association (NAPA) requirements. The fiber length of 1–5 mm was maintained for SW and HSH. The PA standard gradation suggested by NAPA was used to form the stone matrix of the investigated PA mixtures. The Marshall design method was used to obtain the optimum asphalt and stabilizer contents. The performance evaluation tests were performed on SW and HSH mixtures, including loss of stability, moisture sensitivity, draindown, cantabro abrasion and rutting depth. Based on the results of the performance evaluation tests, the PA mixtures stabilized by HSH show a convergent performance compared with those stabilized by SW. The findings indicated that HSH can be considered an adequate stabilizer for PA mixtures instead of SW fibers.

Evaluasi Agregat Lokal Sebagai Lapisan Base Perkerasan Permeabel

Permeable pavement is a type of road pavement that allows stormwater to infiltrate through the pavement surface and the underlying base layer to reduce surface runoff. Open-graded aggregates are often used as the base layers to temporarily store water and allow the water to infiltrate slowly into the soil below the pavement or through sub-drainage. The strength of open graded material is usually less than the dense-graded materials. Therefore; the mixture of the aggregate for both base and drainage layer need to be designed carefully. In Indonesia, the criteria for aggregate as both base and drainage layer is stipulated in Bina Marga Specification. This study aims at designing an optimum mixture of local aggregate to be used as the base of permeable pavement. The mixture should fulfil the mechanical properties based on laboratory CBR value, and hydraulic properties based on storage capacity and the coefficient of permeability. Five aggregate samples of Andesite origin from South Lampung area were selected for this study. Careful laboratory test procedures were adopted to select configurations of aggregate sizes (design mix formula) that satisfies the requirements both as Aggregate A and as drainage layer. A dense graded aggregate based on the grain size distribution was prepared for design mix formula to meet the requirement as Aggregate A. Then, the fine particles passing No 40 sieve was removed to form open aggregate sample suitable as drainage layer. Both samples were tested for grain size distribution, CBR, permeability and storage capacity. Results show that the local aggregate fulfils the requirements both as base and as drainage layer with average CBR of 92%, average storage capacity of 18.32% and average permeability of 0.05 m/sec. The thickness of the permeable pavement layer could be estimated based on storage capacity and the permeability of the drainage layer.

Uniaxial Stress-Strain Behavior for Material Pavement Stabilization by Using Zeolite

The characteristics of semi-flexible pavement (SFP) are strongly influenced by the proportion of cement mortar content filling the voids in the mixture. SFP behavior due to repeated traffic loads causes the pavement structure to experience stress and strain around the wheel axis, resulting in a rapid decline in performance with cracks and permanent defects. Evaluation of the properties of the mixture on the stress-strain parameters of the influence of additives and substitution of many SFP mixture-forming materials has been carried out. The purpose of this study was to determine the stress-strain models of SFP with the effect of waste tire rubber (WTR) additives in asphalt and Aceh natural zeolite substitution in cement mortar under uniaxial compressive load. The porous asphalt mixture is designed in accordance with the optimum asphalt content and open graded aggregate based on the specifications of Bina Marga Regulation 2010 and Australian Asphalt Pavement (AAPA) 2004. The composition of zeolite in SFP mixture can affect the stress behavior, where zeolite can inprove quality of the mortar cement so that it can slow down the development of the SFP mixture flatness and the maximum stress obtained is 17 MPa at 5% zeolite composition. The bilinear model of stress-strains was proposed the results show a good agreement with experimental results.

Evaluation of Open-Graded Aggregates Stabilized with a Multi-Axial Geogrid Using a Large-Scale Triaxial Test Set-Up

Geogrids are commonly used in paved and unpaved roadways to stabilize base and subbase layers by laterally restraining movements of unbound aggregates under applied wheel loading, often referred to as interlocking. The geogrid-aggregate interlock is a function of the match between the geogrid aperture size and geometry and the grain size and shape characteristics of the stabilized aggregates. Open-graded coarse aggregates (OGA) are commonly used as an alternative to dense-graded materials in permeable base/subbase applications as well as in railway ballast to facilitate drainage. This paper describes an experimental study recently conducted to investigate the repeated load-deformation behavior of a geogrid-stabilized OGA material in large-scale triaxial testing. Two multi-axial geogrids with the same aperture patterns but different aperture sizes were tested. The aperture patterns include different sizes of hexagonal, trapezoidal, and triangular openings. The multi-axial geogrid with the larger apertures better matched the OGA material properties to provide a reduction in permanent deformation in the test specimen. The improved interlocking and the related local stiffness enhancement were successfully quantified using embedded shear wave transducers termed bender elements. To stabilize aggregates with relatively uniform grain sizes, for example, AASHTO No. 57 stone studied here and railroad ballast, the ratio between the aperture size and a representative particle size (i.e., D90) served as a good indicator of the effectiveness of the geogrid. The findings of this experimental study therefore provided valuable information on the governing properties and mechanisms that play a role in geogrid-aggregate interaction with multi-axial geogrids.

The behavior of permeable interlocking concrete pavement under different rainfall intensities and design conditions

ABSTRACT This study investigated the behaviour of permeable interlocking concrete pavement (PICP) in terms of water infiltration volume, surface runoff volume, and load resistance, using a specific lab apparatus, designed and manufactured as a rainfall simulator. The connecting pattern of the surface blocks is a stretcher bond pattern with a joint spacing of (5 and 10 mm) between the block pavers to be filled with a small-sized open-graded aggregate to finalise the permeable surface of joints. The adopted pattern has been examined under three rainfall intensities of (20, 40, and 60 l/min), four longitudinal slopes (0, 2, 4, and 6%), and three transverse slopes (0, 2, and 4%). The results showed that at high rainfall intensities (60 l/min), high longitudinal slopes (6%), and high transverse slopes (4%), the stretcher-bonded PICP with 5 mm spacing between the blocks infiltrates less water than the one with 10 mm. Furthermore, PICP with 5 mm spacing has higher surface runoff than PICP with 10 mm spacing at high rainfall intensities (60 l/min), high longitudinal slopes (6%), and all transverse slope percentages (0, 2, and 4%). In addition, the load resistance of stretcher-bonded PICP with 5 mm spacing between the blocks is higher than that of 10 mm at all the subjected loads in the load-deflection test. Despite the shown differences between both types of PICP, they are strongly recommended as an alternative choice for ordinary dense-graded pavement.

Rerounding of Deflected Thermoplastic Conduit in Well-Graded Aggregate Backfill

Rerounding is a technique for remediating excess deflection in thermoplastic pipe using a pneumatic device vibrating along the vertical axis and pushing against the inside crown and invert to restore the original pipe shape and redistribute the surrounding backfill. Since the process has not been evaluated on high density polyethylene (HDPE) pipe outside of a few reports, and the method is routinely used by contractors to remediate deflected thermoplastic pipes, the Ohio Department of Transportation (ODOT) wanted to evaluate the technology as a lower-cost and less disruptive alternative to the removal and reinstallation of deflected pipes. Three 36-in. HDPE pipes were installed in a well-graded crushed stone aggregate, sand, or AASHTO #57 open-graded aggregate (ODOT Structural Backfill, Types 1, 2, and 3, respectively), and two 18-in. pipes were installed in Types 2 and 3 Structural Backfill. Pipes were intentionally installed with substantial deflection (10% or more) and then rerounded. The pipe conditions were measured and monitored by collecting profiles, measuring vertical deflections and monitoring soil pressures, backfill characteristics, and the depth of pipe corrugation before and after rerounding. This paper focuses on Test Pipe 1 installed in Type 1 Structural Backfill, which was the most resistant to rerounding. Pressure data were consistent with the redistribution of backfill particles, particularly fines.

Influence of backfill type on the load-bearing performance of GRS bridge abutments

The influence of backfill type and material properties on the performance of field-scale geosynthetic reinforced soil (GRS) abutment models is investigated. Two alternative types of backfill as recommended in the Federal Highway Administration (FHWA) guidelines (called open-graded and well-graded) were used to build two field-scale model abutments and compare their load-bearing performance under a loading beam. Results are presented and discussed relative to the loading beam settlement, facing deformation and reinforcement strains. The well-graded backfill was found to result in smaller beam settlements and facing lateral deformations, especially at smaller loads that were comparable to service load levels. However, it was significantly faster and easier to compact the open-graded aggregate to the unit weight recommended in the guidelines. Nevertheless, performances of both abutment models were found to be satisfactory relative to the limiting requirements on the beam settlement and facing deformations at service load levels.

Compaction studies on open-graded aggregates using portable impulse plate load test devices

An ongoing research study is focusing on developing deflection-based compaction criteria for open-graded aggregate materials using Portable Impulse Plate Load Test Devices, such as the Light Weight Deflectometer (LWD). LWD tests were conducted on two different aggregate materials (ASTM # 4 and ASTM # 57) in cylindrical molds and a cubic wooden box with sides of 1.22 m. A scaled-up mold with a diameter of 304.8-mm was constructed and used for laboratory testing. Three different methods of compaction were used, and LWD testing was conducted after different levels of compaction. Nine (9) seating drops were necessary for LWD testing on open-graded aggregates. LWD testing in a mold was meaningful only for the large-diameter mold. Five seconds of compaction using a jackhammer was deemed to be adequate for stabilizing the aggregate matrix. Future tasks for this study have also been outlined in this paper.

Evaluating the thermal aging-induced raveling potential of thin friction course (TFC)

Thin friction course (TFC) mixed with open-graded aggregate ranging from 3 to 5 mm, styrene-butadiene rubber (SBR)-modified asphalt emulsion, and cement is constructed to improve the skid resistance of underlying pavements and reduce traffic noise. Considering the small thickness (approximately 5 mm) and open gradation of TFC, the mixture is exposed to environmental conditions over its entire thickness. Therefore, the TFC is vulnerable to aging-induced damage, such as aging-induced late raveling distress. This paper aims to determine the aging-induced raveling performance of TFCs, chemical composition transformation, and raveling-related rheological properties of asphalt emulsion residue via a wet track abrasion test (WTAT), transform infrared spectroscopy (FTIR), and a linear amplitude sweep (LAS) test, respectively. Finally, a correlation analysis was conducted. The results indicate that at the initial aging period, prolonging the aging duration could decrease the raveling potential of TFC. However, late raveling may occur when the TFC specimens are aged for 14d, and the aggregate loss increase with the aging duration. Similarly, the enhanced emulsion and SBR dosages are favorable to improve the raveling resistance of TFC and delay the late raveling of TFC. Regarding the chemical transformation, the existence of SBR latex decreases the aging degree. Furthermore, according to the LAS test, the increased SBR latex contents may improve the fatigue resistance of asphalt emulsion residue owing to the spot-welding effects. Finally, the aging degree index SI correlates well with the raveling potential of TFC with a correlation coefficient of 0.71. Typically, the higher the aging degree of asphalt emulsion, the lower the raveling potential of TFC; the greater the fatigue resistance of asphalt emulsion, the lower the raveling potential of TFC.

Prediction Models Based on Regression and Artificial Neural Network for Moduli of Layers Constituted by Open-Graded Aggregates.

The impermeable cover in urban area has been growing due to rapid urbanization, which prevents stormwater from being naturally infiltrated into the ground. There is a higher chance of flooding in urban area covered with conventional concretes and asphalts. The permeable pavement is one of Low-Impact Development (LID) technologies that can reduce surface runoff and water pollution by allowing stormwater into pavement systems. Unlike traditional pavements, permeable pavement bases employ open-graded aggregates (OGAs) with highly uniform particle sizes. There is very little information on the engineering properties of compacted OGAs. In this study, the moduli of open-graded aggregates under various compaction energies are investigated based on the Plate Load Test (PLT) and Light-Weight Deflectometer (LWD). Artificial Neural Network (ANN) and Linear Regression (LR) models are employed for estimation of the moduli of the aggregates based on the material type and level of compaction. Overall, the moduli from PLT and LWD steeply increase until the number of roller passes reaches 4, and they gradually increase until the number of roller passes becomes 8. A set of simple linear equations are proposed to evaluate the moduli of open-graded aggregates from PLT and LWD based on the material type and the number of roller passes.

Determining the properties of semi-flexible pavement using waste tire rubber powder and natural zeolite

The small amount of bitumen contained in semi-flexible pavement (SFP) causes the peeling of the aggregate grains, therefore, it is necessary to include some additives such as waste tire rubber (WTR) to increase the adhesion. Moreover, natural zeolite contains a high amount of silica and this makes it suitable as a replacement for cement in SFP filling mortar. This research was, therefore, aimed at determining the compressive strength, flexural strength, drying shrinkage, permeability, durability, and the stress-strain relationship of semi-flexible pavement (SFP) using waste tire rubber (WTR) powder as an additive material and natural zeolite as cement replacement. The porous asphalt mix was designed in accordance with the optimum asphalt proportion and open-graded aggregate as specified in the 2010 Indonesian Bina Marga Standards and 2014 Australian Asphalt Pavement Association (AAPA), respectively. The process involved the addition of WTR powder on liquid asphalt at 3%, 4%, and 5% before the porous asphalt was mixed. This was followed by conducting a Marshall test on the specimens to determine if they satisfied the Bina Marga Standards. The porous asphalt specimens were grouted by cement mortar with the cement content replaced by 0%, 5%, 15%, and 25% natural zeolite (w/w) to produce SFP after which the properties of SFP were tested after 14 days. The results showed the best properties were obtained at 5% tire rubber powder and 15% zeolite content.

Compaction Quality Monitoring of Open-Graded Aggregates by Light Weight Deflectometer and Soil Stiffness Gauge

Open-graded aggregates (OGAs) are free-draining materials often used as the base layer of permeable pavements to allow the infiltration or drainage of stormwater. Despite their widespread use, the compaction quality of OGA base layers has not been specified properly. The currently used density-based compaction quality control (QC) has limitations; obtaining the field density and maximum dry density of OGAs by typical methods is challenging, due to their unique properties. To overcome these limitations, modulus-based compaction QC can be used as an alternative. In this study, five different OGAs were chosen and compacted into a specially built soil chamber to measure their densities. The light weight deflectometer (LWD) and the soil stiffness gauge (SSG) were used to evaluate the modulus of the compacted OGAs. The vibratory hammer compaction test was conducted to obtain the maximum dry density of the aggregates. Through these tests, the relationship between the modulus of the compacted aggregates and the relative density was obtained, and efforts to find a modulus range that ensures proper compaction were made. It was found that the LWD and SSG are valid and reliable devices for monitoring the modulus change of OGAs due to compaction.

Resilient Modulus and Permanent Deformation of 40-mm Open-Graded Aggregates based on Repeated-Load Triaxial Tests

Resilient Modulus and Permanent Deformation of 40-mm Open-Graded Aggregates based on Repeated-Load Triaxial Tests

Experimental evaluation of the permanent strains of open-graded aggregate materials

In permeable pavement systems, open-graded aggregates are commonly used for base and subbase layers that allow water to store and drain. At each traffic load cycle, the permanent strain accumulates and is considered to be one of major distresses in permeable pavement systems. This study investigates the permanent strain of open-graded aggregate material using the multi-stage repeated-load triaxial test. For this purpose, the open-graded aggregate materials with three different gradations, from a single quarry, were used. Their nominal maximum aggregate sizes were 13, 25, and 40 mm. In the multi-stage repeated-load triaxial test, the specimen is subjected to five loading sequences and each sequence is comprised of six stress combinations. At each stress combination, the specimen is subjected to 10,000 load repetitions. Based on the test results, the material parameters of the predictive model were determined and then used to predict the permanent strains of three open-graded aggregates in other loading sequences. The test results and the predictions showed that specimen whose gradation bounded by two others happened to have the highest resistance to permanent strain. Regardless of the difference in aggregate sizes, the material parameters of the open-graded aggregates did not vary significantly. In addition, open-graded aggregate materials were more dependent on bulk stress than deviator stress.

The influence of the using waste tire rubber and natural ziolite as Asphalt and Cement replacements to compressive strength of Semi-Flexible Pavement

The objective of this research is to study the compressive strength of semi-flexible pavement by using waste tire rubber and natural zeolite as asphalt and cement replacements. The mix design of porous asphalt is started with a determination of optimum asphalt proportion with open-graded aggregate as specified in Australian Asphalt Pavement Association (AAPA) 2004. The asphalt was then replaced by 3 %, 4 % and 5 % of waste tire rubber and the Marshall test were conducted. The cement mortar with 0 %, 5 %, 10 %, 15 % and 20 % natural zeolite was injected to porous asphalt specimens. The compressive strength test was conducted based on ASTM C670-91a at the age of the specimens of 14 days. The test results showed that the higher compressive strength is reached at the 15 % natural zeolite and 5 % waste tire rubber, which is 15,43 MPa.

Effect of compaction temperature on porous asphalt performance

Porous asphalt is an open-graded aggregate mixed with polymer modified binder that contains relatively high air voids after compaction to allow for water infiltration. The performance of porous asphalt, particularly the strength and durability are highly influenced by compaction temperature. Higher compaction temperature may decrease the mixture air voids, thus failed to achieve required mixture densities and reduce its ability to perform as designed. Meanwhile, lower compaction temperature could potentially increase the viscosity of polymer modified asphalt and decrease the adhesion between aggregates, hence promoted stripping problem on pavement. Therefore, this study investigates the performance of porous asphalt compacted at various temperatures. The samples were prepared by using polymer modified asphalt PG76, granite aggregates and hydrated lime as mineral filler. The materials were mixed and compacted using gyratory compactor at different temperatures. The samples were then tested for volumetric properties, Abrasion loss, Resilient Modulus, Creep and Moisture Susceptibility. Based on the results, it can be concluded that compacting the porous asphalt at low temperature will reduce its performance.

Assessment of Field Compaction of Aggregate Base Materials for Permeable Pavements Based on Plate Load Tests

The permeable pavement is one of Low Impact Development technics that allows stormwater to infiltrate through the pavement surface and the underlying base layer, thereby reducing surface runoff and preventing water contamination. For permeable base layers of permeable pavements, open-graded aggregates are often used to infiltrate and store stormwater in the pore of aggregate base layers. The mechanical behavior of open-graded aggregates has not been a major interest of pavement industry and society, and therefore there is much less information known for behavior of compacted open-graded aggregates comparing to dense-graded materials. This study aims at investigating the mechanical behavior of compacted permeable or open-graded aggregate base materials based on field experiments. Five different open-graded aggregates were selected, and they were compacted in the field up to 12 passes with a 10-ton vibratory compaction roller. The mechanical behaviors of aggregates were evaluated by conducting plate load tests at 2, 4, 8, and 12 passes of roller. For the test conditions considered herein, the strain modulus at the first loading seems to provide more consistent results with respect to aggregate types and level of compaction than other stiffness measures from plate load tests.

Dynamic modulus of nanosilica modified porous asphalt

Porous asphalt (PA) is a flexible pavement layer with high interconnected air void contents and constructed using open-graded aggregates. Due to high temperature environment and increased traffic volume in Malaysia, PA may have deficiencies particularly in rutting and stiffness of the mix. A possible way to improve these deficiencies is to improve the asphalt binder used. Binder is normally modified using polymer materials to improve its properties. However, nanotechnology presently is being gradually used for asphalt modification. Nanosilica (NS), a byproduct of rice husk and palm oil fuel ash is used as additive in this study. The aim of this study is to enhance the rutting resistance and stiffness performance of PA using NS. This study focused on the performance of PA in terms of dynamic modulus with the addition of NS modified binder to produce better and more durable PA. From the result of Dynamic SPT Test, it shows that the addition of NS was capable in enhancing the stiffness and rutting resistance of PA. The addition of NS also increase the dynamic modulus value of PA by 50%.

Laboratory and Field Evaluation of Porous Asphalt Mixes

Porous asphalt concrete (PAC) generally has strongly open-graded aggregate gradations to yield high air voids, and is mainly applied to a surface drainage layer on high-speed trafficked highway pavements. Tests including durability and resistance to drain-down were conducted to determine the mechanical properties of PAC mixtures in the laboratory. The use of polymer-modified binder was shown to minimize the abrasion loss and enhance the durability of the PAC mixture. A test road was constructed to monitor the performance of PAC pavements based on the laboratory results. Surveys for pavement performance were conducted at scheduled intervals. Test results indicated that using polymer-modified binders instead of traditional binder improved drainability of PAC. Friction characteristics appeared to have no correlations with the binder type.

Strain Rate Effect on Shear Behavior of Open-Graded Aggregates

Despite their wide application as construction materials in various earthworks built by state and local transportation agencies, the role of physical and mechanical factors in the strength and deformation behavior of crushed, manufactured open-graded aggregates (OGAs) is not well studied. In this investigation, the strain rate dependency of strength–deformation behaviors of two commonly employed crushed aggregates with small (12.7 mm) and large (38.1 mm) sizes is investigated. A 150-mm diameter triaxial testing device was used to conduct a drained compression test at five strain rates, ranging from 0.000083%/s to 0.0083%/s. To evaluate the significance of confining stress and density on the effect of strain rates, the shear tests were conducted at 34 kPa and 207 kPa effective confining stress levels, with the samples compacted at loose (30%) and dense (95%) relative densities. The peak friction angle, maximum dilation angle, secant modulus, and axial strain at which the aggregates started to dilate were determined to evaluate the strain rate effect on the shear behavior of OGAs. The results demonstrate that within the imposed quasistatic strain rate ranges, only the dilation angle showed an increasing trend with the increase in strain rate, whereas other extracted strength parameters were less sensitive to strain rate for both OGAs tested. Hence, the selection of strain rates according to ASTM specifications is appropriate for conducting strength parameter tests, used by practitioners for the design of geotechnical structures, on OGAs under quasistatic conditions.