Conferencia Asfalto Espumado. Public. · Hosted by IFUCE Cal Química Mexicana. Interested. clock. Wednesday, April 29, at PM UTC More than a. ¿Qué es el asfalto espumado? Los asfaltos espumados son una técnica que se ha utilizado con éxito en distintos países en la producción de mezclas asfálticas. Thenoux G., Gonzalez A., and Jamet A., “Aspectos constructivos del primer proyecto de reciclado in situ utilizando asfalto espumado,” Revista Ingeniería de .
Performance of foamed bitumen pavements in accelerated testing facility. One of the key principal goals of pavement asset management is to develop and implement cost-effective pavement construction and maintenance strategies that achieve the required levels of service and performance.
A sustainable, cost-effective technique for rehabilitating pavements is foamed bitumen stabilization. This paper presents a study on the performance of foamed bitumen pavements tested in the Canterbury Accelerated Pavement Testing indoor Facility CAPTiFfor espumadp scale testing of pavements.
Six pavement sections were tested; the variables were bitumen and cement content; one control section with the untreated unbound material was tested.
Results showed that surface deflections decreased at sections with higher bitumen contents.
Conferencia Asfalto Espumado
After the application of 5, Equivalent Standard Axles ESAsthe sections stabilised with cement only, bitumen only, and the control section all espummado large amounts of rutting. Conversely, little rutting was observed in the three sections stabilised with foamed bitumen and 1.
The rutting results were used to develop models to describe the stable and unstable performance of the tested pavements.
The paper concludes by outlining some of the practical benefits of espmuado this technology in pavement asset management. A typical New Zealand pavement consist of a thin surface usually not exceeding 50 mm thicknessthe basecourse which is constructed from unbound granular material that is usually asfalyo quarried rock or locally sourced aggregate and the subbase which is usually one or sometimes two layers of unbound granular aggregate.
This pavement type has been adopted in New Zealand because in the past high quality aggregate has been readily available in most regions of the country and because in most New Zealand roads, low traffic volumes do not justify the incorporation of thick asphalt pavements, usually constructed in heavy trafficked roads.
However in the last decade areas of New Zealand started to face a complex problem in the supply of high quality aggregates for road construction. A viable alternative to reduce the exploitation of these aggregates is the stabilization or recycling of pavements. Furthermore, New Zealand imports crude oil and therefore its production costs for bitumen are highly dependant on international oil prices.
Research has demonstrated that pavement recycling using foam bitumen reduces energy and oil consumption Thenoux et al. Cold in place recycling of pavements using foamed bitumen is a construction technique that reclaims the existing distressed flexible pavement, simultaneously adding stabilising agents to improve qsfalto properties of the reclaimed material. Although cold in place recycling using foamed bitumen is an attractive alternative to reduce the high quality aggregate supply problem, pavement designers in New Zealand who are trying to use alternative materials are severely constrained by a lack of data on the performance of a range of stabilized espumaxo.
A large research project was conducted in New Zealand to study the effects of foamed bitumen FB stabilisation in the performance, strength and deformational characteristics of pavements.
The investigation consisted of a laboratory study, in which different types of tests were conducted, and a full-scale test, in which accelerated load was applied to FB pavements. Six pavements were constructed using different contents of bitumen and cement. Accelerated loading was applied to the pavement structures and the pavement responses, such as surface deformation ruttingsurface deflections and strains, were periodically recorded during the execution of the test.
A total number of approximately 5. The results showed that foamed bitumen stabilization has an important effect on the performance of the pavements studied, as further detailed in this paper.
The H40 is a crushed aggregate of 40 mm maximum size, with specific gravity of 2.
The H40 aggregate satisfied the following requirements: The H40 aggregate particle size distribution was not directly suitable for FB stabilisation Figure 1 because it was too coarse according to the recommended grading for FB mixes Asphalt Academy Therefore, the H40 particle size distribution was adjusted using an AP5 crusher dust to bring the aggregate into the recommended grading zone.
The maximum particle size of the AP5 is 5 mm, the maximum dry density is 1. The characteristics of the foam were investigated using the foamed bitumen laboratory model WLB10, which has been used by many researchers and practitioners for the production of bitumen foam. The results showed that 2.
The loading asfalti applied during the test corresponds to The results indicated that ITS increases when the bitumen content increases up to about 3. The structural design of pavements was carried out using the South African interim guidelines Asphalt Academy, and the New Zealand supplement to the Austroads pavement design guidelines Austroads, Details of the structural design are not presented in this paper, but a mm basecourse combined with a relatively weak MPa subgrade provided a pavement structural capacity close to 1×10 6 ESAs of 80 kN using both the design methods.
It consists of a m long circular asfalo contained within a 1. A center platform carries the machinery and electronics needed to drive the system. Mounted on this platform is a sliding frame that can move horizontally by 1 m.
This radial movement enables the wheel paths to be varied laterally and can be used to have the esupmado ‘vehicles’ operating in independent wheel paths.
Asfalto espumado by Lucio Borelli on Prezi
One section was retained as a control with the H40 material only, and another section had FB only, to separate the effects of the FB with the cement. A top view of the pavement test track is presented in Figure 2b, in which the six pavement sections are depicted. For instance, section B14C10 was built adding 1.
The top mm of the subgrade was clay, extended in lifts ofand mm, and compacted using a roller available at CAPTIF. Back-calculation analysis using FWD data yields a subgrade stiffness of 60 MPa approximately, which is in agreement with the target stiffness from the structural design of pavements. Once the untreated material was ready the trenches were stabilised with the recycling machine.
A paver was used to place the basecourse material and a steel roller was used for compaction. Before laying the final surface layer, the sections were cured at ambient temperature for 30 days.
All sections were sealed with a single coat chipseal. After a week to allow the chipseal to set up, all sections were surfaced with a skim coat of AC10 hot mix covering the top of the chipseal. The approximate thickness of this surface was 20 mm. Before the sealing, density and moisture measurements were taken using a nuclear gauge directly over the basecourse. Dry densities and moisture contents are included in Figure 2b. During the execution of the experiment and after the application of A thin hot mix asphalt HMA layer of 30 mm was laid over the original surface, leading to a total surface thickness of approximately 50 mm for the rest of the project.
The pavement instrumentation at CAPTIF includes 3D Emu Dawson, soil strain transducers to measure the vertical, transverse and longitudinal strains in the pavement. The final cross section adopted in all pavement sections is shown in Figure 3. The load was a dual truck tire with a separation of mm between the centers of the tires inflated to kPa. However, since little rutting was measured during the early stages of the project, the load was increased to 50 kN afterload cycles and again to 60 kN after The load was applied on one wheel path with a lateral wandering of mm.
FWD deflections with a 40 kN load are presented in Figure 4. The results correspond to deflections measured before the trafficking of the sections 0 load cycles and after 1×10 6 load cycles.
At 2×10 5 load cycles the thin surface layer was overlaid with 30 mm of HMA. The unbound section B00C00 shows considerably higher deflections in comparison with the other sections. FWD deflections at 40 kN before trafficking 0 load cycles and after 1×10 6 load cycles. The averaged rutting measurements for each pavement section are presented in Figure 5. The curves presented show the typical performance of pavements with a bedding-in phase during the initial vehicle loading, followed by a plateau phase.
When the load was increased to 50 kN another increase in the rutting rate was observed. Fromload cycles after constructing the HMA overlay the rutting increased approximately linearly up to 1. The pavement test results presented indicate that stabilisation using FB and cement improved the performance of the pavements. By the end of the test little difference was found in the rutting measurements of sections stabilized with foam bitumen and cement sections B12C10, B14C10 and B28C To accelerate the surface deformation in these sections it was decided to cut part of the pavement sections down from the HMA surface to the top of the basecourse 50 mm-deep cuts.
The cuts were mm apart, and the surface was sawed from stations 3 to 6 in section B12C10, from 14 to 17 in section B14C10, and from 20 to 23 in section B28C Once the cutting job was finished, water was uniformly applied over the surface. With a constant water flow, an additional 60 kN load cycles were applied. The load induced further deformation and surface cracking in the pavement sections.
Nevertheless, the water penetrated into the subgrade causing swelling of this layer and modifying the final levels of the pavement structure. After the application of an additional 42, load cycles under wet conditions, Section B12C10 started to show extensive cracking and further surface deformation in comparison with the other two sections, with evidence of some loss of fines Figure 6.
Conversely, no cracking was observed in sections B14C10 eepumado B28C Photo of pavement section B12C10 left and B14C10 right. Vertical surface deformation contour plots. Transverse surface profiles at each of the 58 pavement stations were taken at several stages of the project.
The profiles were used to calculate the vertical surface deformation VSD by subtracting the original espmado of each transverse profile before loading minus the current transverse profile. The VSD was then used to build contour plots of each pavement section. The VSD data used for the contour plots was taken from transverse location from mm to mm, being mm the location of the centre of the wheel paths. The stations next to the transition zones area between two pavement sections were not used to build the contour plot.
Figure 7 shows the contour plot for sections B28C10 and B00C10 afterload cycles. The figure shows that, as expected, higher VSDs are measured under the wheel paths. In addition, the figure shows the better performance of section B28C10 compared to B00C Vertical surface deformation contour plots of sections B28C10 left and B00C10 right afterload cycles. Rutting modeling of stable and unstable behavior.
Huurmanproposed a four parameters model Equation 1 to describe the permanent strain development in unbound granular pavements under traffic. The model was adapted to describe the rutting development instead of the permanent strain. The four parameters model has the following form: The first term of the model describes the linear increase of rutting with N on a log Rutting -log N scale. The second term of the model describes the unstable behavior observed after 1, load cycles that cannot be described by the first term alone, because an exponential instead of a linear increase of rutting with N on the same log Rutting – log N scales is observed.
The model was fitted to the rutting measured at 3×10 5 load cycles 5. For the model fitting the root mean square RMS was used: Where n is the number of data espumavo, d c is the calculated rutting depth and d mi afalto the measured average rutting. Results of the model fitting are shown in Table 1 top.
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