ICPT - 2021

Permanent URI for this collectionhttp://192.248.9.226/handle/123/20174

Browse

Now showing 1 - 20 of 65

item: Conference-Full-text
Analysis and numerical simulation of semi-circle bending fatigue crack propagation of asphalt mixture
(Springer, 2021) Huang, L; Zhang, P; Song, W; Feng, X; Yang, S; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
In order to study the fatigue crack propagation characteristics of asphalt mixture, a model of fatigue crack dynamically propagating was established based on the Paris law modified with fracture energy release rate. Four different types of asphalt mixture were tested using semi-circular bending fatigue test (SCB fatigue test) to obtain the corresponding N-a curves. The extended finite element method (XFEM)was adopted to simulate the SCB fatigue tests for 4 types of asphaltmixture. The results show that the N-a curve obtained from the finite element model is highly consistent with the experimental results, which verifies the feasibility of fatigue crack propagation analysis based on modified Paris Law characterized by fracture energy release rate for asphaltmixtures. The extended finite element methodwas used to establish the fatigue crack dynamic propagation model of the asphalt mixtures. The fatigue crack propagation process of the specimen was simulated to verify the effectiveness of the method.
item: Conference-Full-text
Analysis of skidding potential and safe vehicle speeds on wet horizontal pavement curves
(Springer, 2021) Peng, J; Chu, L; Fwa, TF; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
Skidding on wet horizontal pavement curves is a major traffic safety concern. Themaximum safe driving speed against skidding is an important threshold for safe driving. However, because of the complex tire-pavement-fluid interaction mechanism and the large number of variables involved (including curve geometric parameters, pavement surface properties, properties of tire in motion, and water film thickness), currently there is no practical working procedure that allows pavement engineers to determine the maximum safe driving speed on a horizontal curve under a given wet weather condition. This paper presents a finite element model to predict the maximum safe driving speed on a wet curved roadway section based on solid mechanics and hydrodynamics. The numerical simulation model was developed and validated against experimental skid resistance values on slip angles from 0° to 90°. Based on skidding analysis, the maximum safe driving speed on a horizontal curve is derived by comparing the available tire-pavement frictional resistance and the required friction to prevent skidding caused by the centrifugal force of the vehicle concerned. An illustrative case study is presented to compare the calculated maximum safe vehicle speed with AASHTO design speed. The analysis presented suggested that the proposed approach offers a useful tool to calculate maximum safe speeds on in-service pavement curves for safe driving.
item: Conference-Full-text
Applicability of gneiss based mineral aggregates for the use in high friction surface treatment in terms of polishing characteristics
(Springer, 2021) Thenuwara, HV; Buddhi, PHGH; Pasindu, HR; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
Speed and safety management of highways plays a prominent role in ensuring road user safety, especially of the vulnerable categories. Pavement Friction Management (PFM) is being considered as the best possible option in developing the road infrastructure over the other prevalent strategies, with the focus of improving user safety. High Friction Surface Treatment (HFST) is widely being used as a remedial measure to improve the friction and texture retention capacity of the wearing course, as it provides economical and sustainable solutions in upgrading the pavement performance in both as an urgent response and in the long run as well. As an urgent remedial intervention, HFST can be incorporated in the national practice of safety management in Sri Lanka, to address the concerns over the escalating numbers of grievous highway crashes. In place of the most commonly used high skid resistant aggregates, gneiss-based mineral aggregate can be a viable alternative since it delivers similar functionality to that of granites. The study examines the polishing characteristics of widely used gneiss-based roadstones in the country through laboratory experiments involving the Polish Stone Value (PSV) test. Both qualitative and quantitative analyses of the specified physical and mechanical laboratory testing are conducted to evaluate the applicability of gneiss-based mineral aggregates in the use of HFST as an alternative skid-resistant roadstone in terms of their polishing behavior.
item: Conference-Full-text
Applications of molecular dynamics in asphalt pavement mixture studies
(Springer, 2021) Wan, H; Chu, L; Fwa, TF; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
The rapid development of high-performance computing facilities and techniques in recent years has made molecular dynamics (MD) a feasible tool for studying the behaviors of asphalt mixtures under various operating conditions. MD is capable of building relationships between chemical structures of material and its macroscopic properties. This study first conducts a literature review of the various applications ofMDin asphaltmixture studies. A summary is made on the techniques and approaches adopted by researchers, and the main application areas of MD in asphalt mixture studies so far. Next, based on the basic concepts of MD, an analysis is performed to evaluate the strengths of the different techniques and approaches adopted, including the types of molecular models employed. Also evaluated are their relative abilities in explaining the behaviors of asphalt mixtures, such as mechanical properties, self-healing and rejuvenator diffusion behaviors, and the stability of asphalt-aggregate interfacial bonding under the influence of several factors. Based on the results of these evaluations, the limitations of MD applications in asphalt mixture studies would be identified. Finally, taking into consideration the strengths and limitations of MD, possible new techniques and potential new application areas are proposed and explained.
item: Conference-Full-text
Areca fiber reinforced alkali-activated black cotton soil using class f fly ash and limestone powder for pavements
(Springer, 2021) Chethan, BA; Shankar, AUR; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
Alkali activation has gained importance in place of cement treatment in construction due to reduced CO2 emissions. The precursors that are rich in silica, alumina, and calcium can be used for soil stabilization with a suitable alkali solution. In this investigation, 0–45% class F fly ash with a constant 5% limestone powder was used to stabilize black cotton soil. These mixes were reinforced with 0.5% areca fibers and stabilized using the alkali solution. Alkali solution was prepared using 8 molar NaOH solution and Na2SiO3 solution with Na2SiO3/NaOH of 1.5. The use of limestone powder has favoured the quick UCS gain on 3 days of room temperature curing. Fiber reinforcement has shown a significant influence on flexural strength and fatigue life improvement. Areca fibers reinforcement has resulted in enormous resistance to plunger penetration during the unsoaked CBR test. However, on further 4 days of soaking, samples lost the bonding and exhibited low CBR. The SEM images showed the compact microstructure of the set mix. The formation of cementitious products is evident from the XRD micrograms due to the dissolution of silica, alumina, calcium, and other compounds by the alkali solution. When subjected to wetting–drying and freezing–thawing durability tests, the set mixeswere failed due to leaching of mineral constituents and further breaking of soil structure. Even though stabilized specimens exhibited significant strength improvement in dry conditions, they are unsuitable in wet conditions.
item: Conference-Full-text
Asphalt pavement texture level and distribution uniformity evaluation using three-dimensional method
(Springer, 2021) Dong, S; Han, S; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
To supplement the research on the evaluationmethod of asphalt pavement texture, novel three-dimensional (3D) methods are proposed. First, pavement textures were measured in laboratory from asphalt mixture specimens using laser texture scanner (LTS), and the macro-texture and micro-texture were extracted based on spectrum analysis techniques. Then, macro-texture level evaluation indices f 8mac and f 9mac together with micro-texture level evaluation indices f 8mic and f 9mic were proposed based on the gray level co-occurrence matrix (GLCM) method, and the hyperparameters existing inGLCMwere discussed. Through the correlation analysis with mean texture depth (MTD) measured by sand patch method (SPM) and friction coefficient μ measured by walking friction tester (WFT), the optimum pavement texture level evaluation indices were determined. Additionally, the evaluation index σ of distribution uniformity of pavement texture (DUPT) was proposed based on the uniformity of deviations between sub-surfaces and the average surface of pavement texture. Finally, the correlations of σ with texture profiles were studied. The results show that f 8mac and f 8mic are the optimum indices for pavement texture level. MTD has significant correlation with f 8mac, and the correlation coefficient R is 0.9348; friction coefficient μ has significant correlation with f 8mic, and the R is 0.8030. The hyperparameters of GLCM selected in this study were proved effective. Moreover, the effectiveness of σ is also validated by calibratingwith standard grooved surface. It can be concluded that the proposed indices in this study are suitable to the evaluation of pavement texture level and pavement texture distribution.
item: Conference-Full-text
Assessment of laboratory and field compaction of dense graded aggregate bases (dgab)
(Springer, 2021) Bambarandage, AR; Jayantha, WRAN; Mampearachchi, WK; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
Dense Graded Aggregate Base (DGAB) construction is a major contributing component in flexible pavement construction in terms of pavement structural capacity and the project cost. However, the production processes related to DGAB construction impose more significant financial, environmental, and social concerns, which stresses the effective compaction in DGAB construction. DGAB compaction process is controlled by three governing factors: moisture content (MC), compaction effort, and layer thickness, where compaction effort can be minimized when field compaction takes place at MC levels closer to the estimated Optimum Moisture Content (OMC). Hence, the relationship among maximum dry density (MDD), OMC, and compaction effort should be well established for a given layer thickness in such a laboratory method that best interprets the field practice. Information on the current industry compaction practices was gathered by conducting a questionnaire survey. Simultaneously, laboratory and field tests were carried out to compare the compaction behavior of DGAB at different MCs and energy levels. Moisture density plots of different laboratory and field compaction tests were compared to determine the most suitable laboratory compaction method to simulate the field compaction of DGAB. The study revealed that the vibratory hammer test resulted in the highestMDDand the lowestOMC,wheremoisture-density curves of the field compaction tests were approaching the vibratory hammer test curve with the increase of compaction effort, emphasizing that the vibratory hammer test best simulates field compaction, when compared to other laboratory impact compaction tests.
item: Conference-Full-text
Assessment of operating speeds of rehabilitated rural roads with asphalt surfacing
(Springer, 2021) Wijeratne, DDS; Dishan, M; Mampearachchi, WK; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
In Sri Lanka, rural roads are not explicitly designed on technical requirements. So far restoration of rural roads went through with mere Construction enhancements and appropriate geometric improvements have not been adopted. Itwas discovered that the actual operating speeds can be higher after restoration which is affecting the safety of road users. Aim of this research is to survey operating speeds, posted speed limits and to find design operating speeds that expected to be after the rehabilitation. The majority of the rural roads in Sri Lanka does not have posted speed limits indicated by the geometric, road environment and functionality level of the road. Consequently, the speed decision of the rural road drivers relies upon variety of different factors. The 85th percentile speed was taken as the operating speed. This speed was utilized as a basic for recommending rational speed limit. Selected roads were divided into a few segments; straight and curved. Operating speed on straight segments were given priority in suggesting rational speed limits. As operating speed in curves are considerably lower and enforcing lower posted speeds only based on operating speeds on curves for entire road and would not be practical. The recommended speed limit for all the roads under purview is 50 km/h and this speed limit will be superseded to a lesser speed limit at a curved segment, dependent on the operating and design speed. This speed limit should be notified using sign boards and shall be enforced only for the curve itself.
item: Conference-Full-text
Assessment of present pavement condition using machine learning techniques
(Springer, 2021) Sharma, M; Kumar, P; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
Quantification of present pavement condition in terms of an index term i.e., Pavement Condition Index (PCI) is one of the most important and primary steps while taking decision related to Maintenance and Rehabilitation of Pavements. PCI as proposed by ASTM D6433 rates pavement in seven conditions viz. Good, Satisfactory, Fair, Poor, Very Poor, Serious and Failed. Determination of rating condition of pavement using distress severity and extent turns out to be tedious process. Hence, present study investigates application machine learning techniques for assessment of present pavement condition. Three different algorithms i.e., Logistic Regression, Naïve Bayes and K-Nearest Neighbor have been tested in the present study using Long Term Pavement Performance database consisting of over 10,000 datapoints. The dataset was divided into 7:3 ratio for training and testing phase. Employed algorithms were tested based on accuracy, precision, recall and f-measure. Logistic Regression Classifier was found to have highest accuracy of 0.92 among three classifiers used in the study.
item: Conference-Full-text
An assessment of the polishing behaviour of road surfacing aggregates in Sri Lanka
(Springer, 2021) Thenuwara, HV; Jayasuriya, WWC; Pasindu, HR; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
Friction capacity between the tire-pavement interface, facilitates sufficient braking force ensuring road user safety. Inadequate skid resistance has been identified as the prominent pavement-related cause of highway crashes. Availability of friction at the wearing course is governed by pavement, vehicle and tire/driver condition parameters combined with environmental parameters, of which pavement-related characteristics concern a greater proportion. Crucial pavement-related characteristics include mineralogical and textural properties of road surfacing aggregates, where the polishing behaviour of coarse aggregates exhibits significant influence in the establishment of skid resistance of asphalt concrete pavings. Thus, many research have been conducted to determine the suitability of aggregates, in terms of resistance to polishing under trafficking. In the national context, broader attention is being developed towards road safety as one of the critical performance parameters due to the integration of an expressway system with the prevailing road network. However, the amount of such extensive study into pavement friction and properties of locally available aggregates, is scarce. No guidelines considering user safety have been specified in the Standard Specifications for Construction and Maintenance of Roads and Bridges by the Institute for Construction Training and Development, Sri Lanka. Therefore, initiatives to incorporate skid resistance in the national practice of aggregate selection for pavement construction, are indispensable. Hence, this study aims to establish the friction characteristics of Sri Lankan natural roadstones, through the Polish Stone Value Test involving the Accelerated Polishing Machine and the British Pendulum Tester, and to evaluate the observed polishing patterns through a petrographic analysis and microscopic investigation.
item: Conference-Full-text
Automatic pavement crack rating for network-level pavement management system
(Springer, 2021) Tan, JY; Nguyen, T; Kapilan, S; Nyunt, TT; Lim, YH; Leong, YF; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
Cracking is one of the important distresses that can be used to trigger pavement maintenance treatments. Traditional crack rating is commonly based on the Pavement Condition Index (PCI) approach involving time-consuming visual inspection and manual classification processes. The emergence of automatic and high-speed laser imaging devices significantly improves the efficiency and productivity of pavement crack data collection but it requires suitablemethods and concepts for automatic crack ratings. This paper discusses the development of an automatic pavement crack rating using crack data collected from a high speed 3D sensor. Two levels of crack ratings are proposed: Level 1 provides detailed crack information including cracking extent, crack types and severity, and Level 2 is a macro-indicator of general/overall cracking extent on a pavement section of 10 m length. The method and concept were developed and tested initially for Singapore expressway network under the effort of the Land Transport Authority (LTA) of Singapore to integrate crack data into the pavement management system (PMS).
item: Conference-Full-text
A brief review: application of recycled polyethylene terephthalate as a modifier for asphalt binder
(Springer, 2021) Zair, MMB; Jakarni, FM; Muniandy, R; Hassim, S; Ansari, AH; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
The management of the waste materials produced on the earth is one of the highly substantial environmental issues. Hence, the increasing usage of plastic every year is one of the concerns across the entirety of theworld. The limiting landfill conditions and higher production of the waste plastic materials stress the researcher to manage it alternatively. Conversely, the growing number of heavy vehicles on roads cause road distress to asphalt pavements that contain pure asphalt binders that are insufficiently resistant. Civil engineers and scientists have attempted to address such issues by enhancing the performance of asphalt pavement via modification of asphalt binders’ properties. This paper summarized the possible utilization of waste polyethene terephthalate (PET) for binder modification. It has been evaluated that the PET can significantly improve the binder properties. The chemical modified PET showed better performance in term of physical and rheological properties. In addition, the compatibility of PET with binder has been highlighted with modified chemical structures and viamorphological assessment of modified binder. In addition to solving landfilling issues of waste PET plastic, such recycling approaches generated in these studies can also be used by asphalt researchers to explore future avenues of improvement for the characterization of asphalt binder as a paving material.
item: Conference-Full-text
Carbon footprint assessment of steel slag asphalt pavement in Singapore
(Springer, 2021) Lol, SS; Subramaniam, SK; Xusheng, H; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
Electric Arc Furnace (EAF) Steel Slag is a by-product generated from the steel-making process which is being used as aggregates for the road construction wearing course.Replacement of naturally occurring aggregates with locally available EAF steel slag as a road construction material would promote sustainability of road construction, reduce carbon footprint and minimise the environmental impact of the steel making industry. Since 1994, 100% of steel slag generated in Singapore has been fully recycled into aggregates and used in the asphalt wearing course on roads by LTA and PUB and within the ports by PSA. Climate change is one of the greatest challenges of our time and a major threat to the livelihoods of living creatures on earth. Greenhouse gasses generated from human activities is no doubt the biggest contributor of climate change observed since the mid-twentieth century. Carbon footprint is one of the most widely used tools to quantify greenhouse gases for assessing the environmental impacts of a production activity. The amount of carbon dioxide and other greenhouse gases associated with a given product can be calculated and expressed asCO2 equivalent. This paper briefs the applications of steel slag aggregate for asphalt pavement in Singapore and compares the carbon footprint of locally produced steel slag aggregates with imported granite aggregates. The environmental benefits of using steel slag have been assessed through the comparison of embodiedCO2 emission values for steel slag aggregate and granite aggregate. Data used in the calculations include electricity usage, diesel consumption, transportation and use of explosives. The analysis reveals that carbon dioxide equivalent emissions decreases as the use of EAF steel slag aggregates increases. The transportation of granite aggregates into Singapore represents a significant contribution to its overall carbon footprint. Thus, using steel slag aggregates generated locally in Singapore would contribute a smaller carbon footprint to the asphalt wearing course making process and reduces the disposal of non-incinerable waste to the landfill site.
item: Conference-Full-text
Challenges for the compaction and proving of granular fills and layers in airport pavements
(Springer, 2021) White, G; Anstee, H; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
The compaction and proving of granular materials during construction is fundamentally import to airport pavement design practice. This is particularly so in countries that make significant use of granular base courses with relatively thin asphalt surfaces, such as Australia. The compaction of dredged sand fills, up to 1500 mm deep is also important where airport pavements are constructed over low bearing capacity marine clays, primarily in areas of reclaimed land. The large 180 tonne Supercompactor for compacting sand fills is no longer available in Australia and the 50 tonne Macro rollers for proving granular pavement layers were downgraded from 1400 to 1000 kPa tyre pressure. Meanwhile, large commercial aircraft have ever-increasing tyre pressures and wheel loads. This has created a challenge in the form of a gap between roller capability and aircraft demand. The gap is relatively minor for the compaction of deep sand fills, but the inability to theoretically compare the effect of static rollers with that of vibrating and impact rollers makes this difficult to quantify. The alternate is an expensive field trial to demonstrate acceptable sand density at depths to 1500 mm. In contrast, a significant gap exists for the proving of fine crushed rock layers used in upper base courses under thin (60–100 mm) asphalt surfaces. This challenge requires rollers with higher tyre pressure or significantly thicker asphalt surface courses to be adopted, both of which are expensive.
item: Conference-Full-text
Chemical properties of modified bitumen incorporating coconut char
(Springer, 2021) Mamat, R; Hainin, MR; Hassan, NA; Warid, MNM; Satar, MKIM; Rahman, NAA; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
Agriculture waste have many advantages such as high specific strength and modulus, low density, renewable nature, biodegradability and absence of health hazards. This advantage is good for construction industry because it can improve the properties of the composites. The coconut fruits contain 40% coconut husk, 30% fiber and 30% dust, consisted of flesh, shell and fiber and chemical composition such as cellulose, lignin, charcoal, acid and potassium. The advantages of coconut shell are strong, rigid and lightweight material, very economical as large amounts are available as agricultural waste material and environmentally friendly. This paper presents the performance of modified binder incorporating coconut char in terms of chemical properties. Fourier Transform Infrared Test (FTIR), Particle Size Analyzer Test (LPSA) and Elemental Analyzer Test (EA) were used to analyze the chemical properties on modified binder. Based on the findings, the increased content of char affects the performance of bitumen significantly, as the bitumen maintains stability and homogenous state even though placed in high temperature condition. The testing result value of FTIR and LPSA are increased with the increased content of coconut char. Based on the results, the modified mixture has the higher chemical components and porosity compared to original bitumen and coconut shell because of the modification.
item: Conference-Full-text
Clogging resistance of high strength pervious concrete
(Springer, 2021) Lee, MG; Wang, YC; Wang, WC; Yatsenko, EA; Wu, SZ; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
This clogging resistant study includes high strength pervious concrete (HSP) and normal pervious concrete (NSP). The HSP concrete aims to carry out 28- day strength above 42 MPa and porosity as close to 10% as possible to achieve the technical specifications. Some of the key tests were porosity, compressive strength, and permeability test. Experimental simulation of sand and soil clogging tests ofHSP pavement specimens were under evaluation. The test results indicate that the 28-day compressive strength of HSP higher than 42 MPa can be achieved with specific mix design and compaction energy by Proctor tamper, and their porosity ranged from 7.3 to 11.6%. The coefficient of permeability for HSP and NSP concretes meets Taiwan code requirements for structural concrete. The sand and soil clogging results show that all HSP specimens had better maintenance by vacuum sweeping and restored 60–75% of the overall permeability, while the high-pressure washing only improved the permeability by 4–6%. The reason is that the maximum water pressure of the test equipment is seriously insufficient. It is presumed that the pressure washing maintenance caused sand and soil to penetrate into the pores of the HSP specimen. Furthermore, a predictive model of the clogging potential of porous asphalt mixture has been found to fit well to HSP pavement.
item: Conference-Full-text
Comparative assessment of cmsdbc and hmsdbc competency
(Springer, 2021) Prakash, G; Suman, SK; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
Over ninety percent of the total road network in India, including the airfield pavements, are flexible pavements with black-top surfaces. The construction of wearing and binder courses of a flexible pavement require high energy consumption during heating of bitumen and aggregate, with consequent giant emission of greenhouse gases during the preparation of hot-mixed bituminous mixtures. Earlier, in flexible pavements, the use of bitumen emulsion was restricted to only spray applications and as dust palliatives, but over the years, with the development of new types, grades, specifications, and availability of improved construction equipment and practices, emulsion-based cold mix technology offers a wide range of solutions. Judicial selection and appropriate use of these technologies can yield significant economic benefits, environmental benefits, and energy security as far as construction and maintenance of roads are concerned. Hence, this paper aimed to compare the strength, durability, and performance of a cold mix semi-dense bituminous concrete (CMSDBC) and hot mix semi-dense bituminous concrete (HMSDBC) pertaining to competency. Materials for the preparation of representative samples are coarse aggregate, fine aggregate, and cement as a filler, in suitable proportions mixed with bitumen or slow-setting cationic bitumen emulsion (where applicable). Tests like Marshall stability, Indirect tensile strength, moisture susceptibility, and rut depth using wheel tracker device were carried out according to standard guidelines. The results showed that CMSDBC yielded significant values, which are comparable with HMSDBC. It infers that CMSDBC is capable to be exercised in the practice for low traffic, low rainfall, moderate and cold climate regions.
item: Conference-Full-text
A comparative investigation on the effectiveness of awax and a resin based curing compound as an alternate of water curing for concrete pavement slab
(Springer, 2021) Goel, P; Kumar, R; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
In this study, the effectiveness of two easily available concrete curing compounds in the Indian construction Industry namely; wax and synthetic resinbased, in comparison with water cured cubes and beams specimens of a paving concrete of 39 MPa compressive strength and 4.5 MPa flexural strength at 28-day has been reported. The concrete specimens were cast and kept for curing under different conditions such as in water, in the sunlight, and under the sunshade. Two coats of curing compounds as per the manufacturer’s instruction were applied on the surfaces of the concrete specimens and put in the sunlight and under the sunshade. The compressive and the flexural strength in comparison with water cured concrete specimens were evaluated. The study has shown 12% lower compressive strength and about 7% lower flexural strength for concrete samples cured with resin-based curing compound than the water cured samples. The study also indicates a reduction in compressive and flexural strengths of about 33% and 11%, respectively for waxbased curing compound. Finally, the study shows an upper hand for the resin-based curing compound, however, neither of them has shown potential as an alternate for the conventional water curing.
item: Conference-Full-text
Comparison of flexible airfield pavement designs using faarfield v1.42 and apsds 5.0
(Springer, 2021) Chai, G; Bell, P; McNabb, K; Wardle, L; Oh, E; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
A case study has been carried out to compare the design of airfield pavements for a major airport using FAARFIELD v1.32 and APSDS 5.0. For the aircraft departure data used in the study, the pavement analysis shows that the APSDS 5.0 design method yielded pavement structure thicknesses that are nearly the same as FAARFIELD v1.32 for CBR greater than 10%. An adjustment factor kc is required for APSDS design thickness to produce designs that are consistent with FAARFIELD for CBR less than 10%. In May 2017, FAA developed new subgrade failure models for flexible pavements in FAARFIELD v1.41 using the full-scale traffic test data collected at the NAPTF for Test Sections in Construction Cycles CC3 and CC5. FAARFIELD v1.41 was subsequently updated and evolved to version 1.42 in September 2017. In this paper, a comparison is carried out using the latest version of FAARFIELD v1.42 to examine if the new subgrade deformation models compute the design thicknesses that are compatible with that generated by APSDS 5. For the Boeing 737-800 (Code C) and 777-300ER (Code E) aircrafts spectrum and 100,000 movements analyzed in the study, the new subgrade failure models developed for the latest version of FAARFIELD generate the flexible pavement thicknesses that are not significantly difference from that of APSDS 5.0 for subgrade CBR ≥5%. The new failure model in FAARFIELD v1.42 produces flexible design thicknesses that differ less from APSDS 5.0 than FAARFIELD v1.32. The design thicknesses are more consistent for B737-800 with 2 wheels configuration. However, the differences are observed to be larger for CBR ≤5% when modelled with B777-300ER having 6 wheels configuration. The differences in the design thickness are attributed to the different coefficients adopted in the subgrade failure models in the design software.
item: Conference-Full-text
Development of design guidelines for composite-geogrid reinforced unpaved pavements
(Springer, 2021) Jayalath, CPG; Gallage, C; Wimalasena, K; Pasindu, HR; Bandara, S; Mampearachchi, WK; Fwa, TF
It is well-known that the inclusion of composite geogrids (CGGs) into the pavement structure assists to maximise the benefits of geosynthetic-reinforcement in flexible pavements. However, the use of CGGs in practice is limited in Queensland, Australia regardless of its potential benefits, mainly due to the absence of rational design guidelines. Therefore, this study was conducted to develop guidelines to design unpaved granular pavements/working platforms constructed with local pavement materials and reinforced with CGGs at the base-subgrade interface. Firstly, six laboratory-scale pavement model tests were conducted varying the granular base thickness as 200, 300 and 400 mm, and with and without the CGG reinforcement at the interface of the subgrade-base layer. In all these tests, a 500 mm thick subgrade was prepared to achieve a CBR value of 2.5%, and then the granular layer was compacted on top of the subgrade to achieve 91% of its maximum dry density, in a steel box with length, width and height of 1 m, 1 m and 1.2 m respectively. The pavement models were subjected to repeated loading (up to 150, 000 cycles) at the centre using a 200 mm diameter plate to simulate the maximum tyre pressure of 550 kPa. By following a step-by-step procedure, design guidelines were developed based on the rut depths of both the reinforced and unreinforced pavement models obtained after 5000 load cycles and every 25,000 load cycles up to 150,000. Both economic and environmental benefits can be obtained by adopting the proposed guidelines.

Browse

Browsing ICPT - 2021 by Title