Study of Asphalt Binder Oil Residue and Municipal Solid Waste Ash to be Used in Low Traffic Pavements

The great generation of urban solid has been a concern in several countries. This work presents a study with two materials: the asphalt binder oil residue accumulated in the bottom of asphalt tanks and the municipal solid waste ash, to be used, respectively, as a substitute of conventional binder in asphalt mixtures and for soil stabilization in pavements base layers. Were evaluated properties as the mechanical behavior of the mixtures through experimental tests. The results show the potential of incorporating these residues for low traffic roads, allowing the construction of low cost roads and an environmental use of the residue. Asphalt Binder Oil Residue All operations in the petroleum industry generate a great number of oily residues. The refineries are responsible for most of such residues. Some products are accumulated in the bottom of the oil tanks. The residue studied is basically composed of emulsions of heavy oil, water and solids. Its variable composition, which is associated with the production in a refinery, makes it difficult to reuse the material. The residue studied was provided by the Refinery Lubnor/Petrobras, located in Fortaleza/Ceará, northeast Brazil. The generation of this type of residue varies in time and it also depends on the production capacity and generation of asphalt binder in the refineries. It is further associated with the maintenance of the storage tanks. The experience accumulated with this type of material is restricted to techniques of environmental treatment and use as a material in systems of waterproofing of sanitary embankments. The aggregates were selected to fit gradation C of the Brazilian Federal Department of Roads (DNER). A coarse aggregate of maximum size of 3⁄4” was used along with material passing sieve # 200, with real densities of 2.651 and 2.655, respectively. All aggregates are of granite origin, including the referred filler. Los Angeles Abrasion of the coarse aggregate was 49% DNER-ME 35 317/97. For the preparation of the laboratory mixture specimens, aggregates were sieved in all sieves between 3⁄4” and #200 to assure the least variation of the target gradation curve. The binder used in the study is an AC 50/70 refined at Lubnor/Petrobras. The residue known as asphalt binder oil residue results from the accumulation of material removed from the bottom


Asphalt Binder Oil Residue
All operations in the petroleum industry generate a great number of oily residues.The refineries are responsible for most of such residues.Some products are accumulated in the bottom of the oil tanks.The residue studied is basically composed of emulsions of heavy oil, water and solids.Its variable composition, which is associated with the production in a refinery, makes it difficult to reuse the material.The residue studied was provided by the Refinery Lubnor/Petrobras, located in Fortaleza/Ceará, northeast Brazil.The generation of this type of residue varies in time and it also depends on the production capacity and generation of asphalt binder in the refineries.It is further associated with the maintenance of the storage tanks.The experience accumulated with this type of material is restricted to techniques of environmental treatment and use as a material in systems of waterproofing of sanitary embankments.
The aggregates were selected to fit gradation C of the Brazilian Federal Department of Roads (DNER).A coarse aggregate of maximum size of ¾" was used along with material passing sieve # 200, with real densities of 2.651 and 2.655, respectively.All aggregates are of granite origin, including the referred filler.Los Angeles Abrasion of the coarse aggregate was 49% DNER-ME 35 317/97.For the preparation of the laboratory mixture specimens, aggregates were sieved in all sieves between ¾" and #200 to assure the least variation of the target gradation curve.
The binder used in the study is an AC 50/70 refined at Lubnor/Petrobras.The residue known as asphalt binder oil residue results from the accumulation of material removed from the bottom of the storage tanks of conventional asphalt at the referred refinery.According to Magalhães (2006) the residue is considered of Class I (dangerous).Penetration tests, according to DNER ME-003/99 indicated that the residue's penetration is approximately 35% greater than the penetration of AC 50/70.Brookfield viscosity and the subsequent compaction and mixture temperatures were determined based on ASTM D 4402 (2002) and ASTM D 2493ASTM D (2001) ) at three different temperatures: 135, 150 and 175°C.The AC 50/70 presented higher viscosity than the oil residue (about 30-40% higher).The variation decreased with the increase in temperature.Mixing and compaction temperatures were approximately 10°C lower for the residue when compared to the conventional AC.
In Brazil, the AC optimum content in HMAs is typically determined using the Marshall Procedure NBR 12891/93 or local adaptations of the procedure.Five groups of three samples with different binder contents are prepared.A first content is based on the local design experience with the components used in the mixture.The other four contents are within ± 0.5% and within ± 1.0% of the first arbitrary content.The theoretical maximum density (TMD) was determined based on the Rice test ASTM D 2041ASTM D (2000)).The volumetric parameters used for selecting the binder content are: void in the mineral aggregate (VMA), volume of voids (Vv), bitumen-void ratio (BVR) and apparent density.The optimum binder content was determined from Vv and BVR, according to Soares et al. (2000).All of the samples presented volumetric parameters that satisfy the recommendations of DNER-ES 313/97 with respect to desired intervals of volume of voids (3-5%) and for the bitumen-void ratio (75-82%).The optimum binder contents found (Table 1) were a little above typical content for conventional mixtures using the same aggregates.(Motta, 1995).The tests performed in the present research followed (DNER-ME 133/94).RM was determined in lab samples (diameter of 10 ± 0.02 cm and height of 6.35 ± 0.20 cm), at 25°C.Instantaneous and not total strain is considered in the determination of the RM.The results are presented in Table 2.The tensile strength results for the mixture with 100% residue as the binder presented lower values when compared to the conventional HMA investigated.As for the resilient modulus, the results of the mixture with 100% residue are not far from results of conventional mixtures.Nevertheless, the RM value is approximately 27% lower when compared to the mixture with pure AC.The differences can be related to the lower viscosity of the residue when compared to the viscosity of the pure AC.In the binder formed by a mix of pure AC and residue, it is noted that the results are improved as the AC content increases in relation to the residue content, which is expected.
Mixture fatigue is typically obtained under diametral compression.The mixture with the residue as the binder presents the lower fatigue life, when considering the same stress state.The mixture with the pure AC and the one with 60% AC + 40% residue preformed very similarly, especially under lower stress states (Figure 1).The results indicate that a mixture with 100% residue should not be used under high traffic volumes but may be used for low traffic roads.Whereas a combination of AC and residue allows the use of a substantial amount of residue (40%) even for high traffic volume roads.Such percentage of residue represents an economy of approximately US$ 8,000/km.

Municipal Solid Waste Ash
The use of alternative materials is not common practice in geotechnical engineering.Recent research has been conducted, aimed at this goal.It is not always possible to find natural soils that meet the requirements of the specifications for the use of stabilized bases and sub-bases without granulometric mixture.The soil, when found, is located far from infrastructure, which increases the costs for transportation.An alternative to minimize the high costs is stabilizing the soil with waste.The proposition of this study should be preceded by a prior knowledge of the potential and limitations of the regional materials.
This study evaluates the application of fly ash obtained from incineration of Municipal Solid Waste (MSW) use in base layers of pavements, by mixing the ashes with a non-lateritic regional clay soil.The Usina Verde is a privately held company located in the Federal University of Rio de Janeiro, and aims to provide environmental solutions for the disposal of municipal solid waste, through incineration with energy co-generation.The Usina Verde receives, daily, 30 tons of MSW Company's Waste Disposal of Rio de Janeiro.In sorting, recyclable materials are segregated manually and with metal detectors.Then the MSW is crushed and separate fine material and sent to drying.These wastes are sent to the incinerator, which operates at a temperature of 950ºC.
During the combustion process, two ashes are produced: bottom ash and fly ash.The bottom ash is deposited in the bottom of the chamber after combustion, referred to the storage tank and arranged into buckets.The hot gases and fly ash are exhausted chamber afterburner and inhaled into the recovery boiler, which is used to produce energy.Subsequently, the gases are neutralized in a set of washers and then the clean gases are extracted and discharged into the atmosphere.The wash solution is collected in settling tanks where the neutralization takes place with the ashes of the process and calcium hydroxide, which causes mineralization and this solution, is reused in the washing process.Then, the ash is sent to settling tanks where it is periodically removed and stored in buckets.
At the end of the incineration process are obtained from 8 to 10% by volume of the two ashes, which represent about 80% of bottom ash and 20% of fly ash (Fontes, 2008).
Fly ash is an effective agent for chemical stabilization in soil mechanics, changing the soil density, moisture content, plasticity and resistance of soils.Typical applications include: stabilization of soils to increase the strength, drying the soil and control of the contraction-expansion (ACAA, 2003).
The non-lateritic clay soil in study came from a deposit located in the city of Campo Grande/RJ.Fly ash comes from the burning of municipal solid waste (MSW) at Usina Verde, which is located on Rio de Janeiro/RJ.
The main chemical components of soil, which are normally found in residual soils, are SiO2, Al2O3 and Fe2O3, which participates actively in the process of chemical stabilization of soil (Rezende, 1999).These components were also obtained by Nascimento (2005), for three non-lateritic clays and Brant (2005) for three residual soils of basalts.The soil and MSW fly ash chemical composition can be observed on Figures 2 and 3.It is notable the variability of the chemical composition of fly ash.It is noteworthy that the chemical composition of MSW fly ash under study is similar to that typical of fly ash from lignite coal mentioned by Winterkorn (1990), which has cementing properties.The geomechanical behavior of soils stabilized with MSW fly ash and fly ash from lignite coal can be compared.
Regarding the characterization of soil, MSW fly ash and mixtures can be noted as follows: first, the limits of Attemberg for pure MSW fly ash could not be performed due to the behavior of granular material, which during the test did not show plastic characteristics to their achievement.Second, that the inclusion of MSW fly ash decreases the liquid limit and plasticity index, and increases the plastic limit of soil.These results are comparable to the study by Bin-Shafique (2009), in which the addition of coal fly ash reduced the plasticity index of an expansive soil and a soft soil, both soils from Texas, USA.Nalbantoglu (2004) tested a coal fly ash to assess its stabilizing effect on two expansive soils on the island of Cyprus.In his study was found that the fly ash decreased the plasticity index of soils with highly plastic, but has less influence on the plasticity index of soils of low plasticity.
Regarding the classification MCT (Nogami and Villibor, 1995), the soil is classified as NG' behavior "non-lateritic-clay."These soils when compacted under the conditions of optimum moisture content and density maximum energy normal characteristics of the traditional very plastic clays and expansive.The use of these soils is related to restrictions resulting from its high expansibility, plasticity, compressibility and contraction when subjected to drying, its use is not recommended for base pavements, and some of the worst soil for the purpose of paving, from the tropical soils (Nogami and Villibor, 1995).
Curves of soil compaction and mixtures with fly ash obtained from the Modified Proctor tests, it can be stated that by increasing the level of ash in the mixture, the maximum dry density tends to decrease, which is consistent with research by Nicholson (2003), on the use of coal ash to stabilize tropical soils.Can be observed that the optimum moisture content decreases a level of 20% fly ash and grows to a maximum of 40%.
The results of Resilient Modulus tests (Figures 4 and 5) show that the Resilient Modulus of soil in study is dependent on the deviator stress and even adding the MSW fly ash, this behavior does not change.It is appreciated that the higher the deviator stress, the lower the value of resilient modulus.
The mixture with 20% MSW fly ash improved the mechanical behavior of pure soil, the mixture with 40% MSW fly ash downgrade the mechanical behavior, but it improved with cure time (Figure 6).Other influence factor is the cycle number of cycling load (Figure 7).The resilient modulus improved with cycling loading.fly ash havior of t did not ievement.
fly ash ty index, il.These by Binf coal fly xpansive as, USA. to assess soils on ound that x of soils ce on the .gami and as NG' ils when optimum m energy nal very of these from its bility and its use is and some ing, from 1995).s with fly r tests, it el of ash y tends to earch by l ash to d that the level of f 40%.The MSW fly ash decreases the expansion of the material (Figure 8), however, high content of fly ash when can deteriorate the mechanical behavior, resulting in a thicker layer.The MSW fly ash decreases the expansion of the material (Figure 8), however, high content of fly ash when can deteriorate the mechanical behavior, resulting in a thicker layer.for MSW fly ash and soil stabilized with 40% fly ash content.The mixture is classified Nondangerous and non-inert (Vizcarra, 2010).
The behavior of mixtures with MSW fly ash should be carefully evaluated for various MSW fly ash content, analyzing the results of physical, chemical, environmental, and mechanical together.

CONCLUSIONS
 It was possible to produce a mixture with a mechanical behavior similar to a conventional HMA, specifically with 60% AC + 40% asphalt binder residue.The results indicate that a mixture with 100% of asphalt binder oil residue can be used in low traffic volume roads.Either combined or by itself in low traffic roads, the use of the residue represents not only great cost economy, but also an environmentally friendly solution for a current problem of the petroleum industry;   for MSW fly ash and soil stabilized with 40% fly ash content.The mixture is classified Non-dangerous and non-inert (Vizcarra, 2010).
The behavior of mixtures with MSW fly ash should be carefully evaluated for various MSW fly ash content, analyzing the results of physical, chemical, environmental, and mechanical together.
Figures 4 of soil in tress and vior does igher the resilient

Fig. 6
Fig.6 Resilient modulus vs. stress of soil with 40% of MSW fly ash.cure time variation.

Fig. 6
Fig.6 Resilient modulus vs. stress of soil with 40% of MSW fly ash.-cure time variation.

Fig. 7
Fig.7 Resilient modulus vs. stress of soil stabilized with 40% of MSW fly ash -cycles number variation.

Fig. 7
Fig.7 Resilient modulus vs. stress of soil stabilized with 40% of MSW fly ash -cycles number variation.

Conclusions◆
It was possible to produce a mixture with a mechanical behavior similar to a conventional HMA, specifically with 60% AC + 40% asphalt binder residue.The results indicate that a mixture with 100% of asphalt binder oil residue can be used in low traffic volume roads.Either combined or by itself in low traffic roads, the use of the residue represents not only great cost economy, but also an environmentally friendly solution for aRevista de EngenhariaCivil IMED, 1(2): 23-29, 2014 -ISSN 2358-6508current problem of the petroleum industry; ◆ Mixtures with MSW ash inclusion had a mechanical behavior compatible with the requirements for a low traffic volume.The inclusion of 20% of fly ash on the non-lateritic clay soil improved the mechanical behavior and reduced the expansion of the soil.The soil mixed with a content of 40% of fly ash worsened the mechanical behavior compared to pure soil, with the consequent increase in thickness; however, improved with cure time and cycle loading number, decrease significantly the expansion of the soil.The results were satisfactory, being dependent on the ash content added, cure time and cycle loading number, highlighting the positive work of MSW fly ash for use in base layers of road pavements, eliminating the current problems of waste disposal in dumps and landfills, putting a noble application to this material.

TABLE 2 :
Tensile strength and resilient modulus