Final Year Project 1

Final Year Project 1

STUDENT NAME: MD RAJIB AHMMED

SUPERVISOR: DR NOOR KAZI

DATE OF SUBMISSION: 19 AUG 2022

Influence of material types and orientations on the structural performance of flexible pavements

Student Name: MD RAJIB AHMMED

Student ID: 19185574

Final Year Project 1

Contents

TOC o "1-3" h z u ABSTRACT PAGEREF _Toc111769843 h 4INTRODUCTION PAGEREF _Toc111769844 h 4Structural Components PAGEREF _Toc111769845 h 4Pavement Materials PAGEREF _Toc111769846 h 5MATERIAL PROPERTIES PAGEREF _Toc111769847 h 6MATERIALS SELECTION PAGEREF _Toc111769848 h 7Factors influencing Material Selection PAGEREF _Toc111769849 h 8Pavement failure model PAGEREF _Toc111769850 h 9PAVEMENT FAILURE PAGEREF _Toc111769851 h 10Literature Review PAGEREF _Toc111769852 h 11Recycled Concrete Aggregate PAGEREF _Toc111769853 h 11Super Hard Asphalt (SHA) PAGEREF _Toc111769854 h 11RCA and Steel Slag PAGEREF _Toc111769855 h 12Marble quarry PAGEREF _Toc111769856 h 13RFAP (RECYCLED FINE AGGREGATE POWDER) PAGEREF _Toc111769857 h 14Recovered Crushed Glass (RCG) PAGEREF _Toc111769858 h 15Research Gaps and Questions PAGEREF _Toc111769859 h 17CONCLUSION PAGEREF _Toc111769860 h 17PROJECT TIMELINE PAGEREF _Toc111769861 h 18REFERENCE PAGEREF _Toc111769862 h 18

ABSTRACTFlexible pavement design methods compare the allowable and design traffic loadings for selecting a pavement structure suitable for in-service conditions. Current design practices are based on specific and limited design database and use of conventional construction materials. Types and placement of materials within the multi-layered structure of pavements determine their performance.

Considerable studies have been conducted in the recent past on various pavement design parameters. However, limited information is available on the effect of the orientation and use of recycled materials on the performance of flexible pavements. The proposed study will investigate the performance of flexible pavements using various types of materials and orientations within the multi-layered systems.

INTRODUCTIONA road pavement is a structure made up of stacked layers of selected and processed materials that is laid down on top of the subgrade, or basement soil. There are two types of pavements: flexible and rigid pavement. A flexible pavement is made of multiple layers of bitumen bound and unbound granular materials with a bituminous top surface. Bitumen bound asphalt allows deformation under load without cracking. There are now over 800,000 kilometres of road in Australia where 310000 kms are flexible pavement.

Structural ComponentsA typical flexible pavement consists of 4 layers (fig: 1). They are:

Wearing Surface: This is the top layer of the pavement where traffic moves. It provides smooth and comfortable riding surface, bears traffic loads, prevents skidding and minimize noise.

Base Course: It is placed on the Base or Sub-base. This layer bears the main traffic loading, hence, made of high-quality materials. Mechanical features like Shear strength, Volume Stability, moisture run off, load bearing are the functions provided by the Base.

Sub-Base: Placed between Subgrade and Base, the Sub-Base enhances Subgrade quality to accommodate Base Course. It is of low shear strength, therefore, made of low-quality materials. Thickness of the Base and Sub-Base reduces Stress put on Subgrade significantly.

Subgrade: This is the deepest prepared layer on which the pavement stands. It supports the pavement without causing considerable deflection, which would compromise the pavement's performance.

Figure 1: Layers of a typical flexible pavement

Pavement MaterialsVarious materials categorised mainly in 4 sections are used in flexible pavement construction.

1. Unbound Granular Material: The grading of these unbound materials ensures that they are mechanically stable, workable, and compactable. Through particle interlocking, they develop shear strength. Due to wedge action, shear strength increases as particle angularity increases. For example: crushed rock, clay brick aggregates, gravels etc.

2. Modified Unbound Granular Material: Unbound granular materials that have been modified by adding modest amounts of stabilising agents to improve their qualities are known as modified unbound granular materials. They are modelled in the same way as unbound granular materials when it comes to pavement design. For example: cement and fly ash mixed crushed rock.

3. Cemented Material: A cementitious binder, water, and granular material are used to make cemented products. In the early stages of the hydration process, ingredients are mixed and compressed to form a pavement layer. Portland cement, mixed cement, lime, chemical binders, fly ash, and blast furnace slag are examples of cementitious binders used in cemented materials.

4. Asphalt: Asphalt is a heated combination of bitumen and gravel that is spread and compacted to form a pavement layer. Bitumen is commonly used as a bituminous binder, however compounds such as polymers can also be utilised. Particle interlocking, i.e., friction between aggregate particles, adhesion between the bitumen and aggregates, cohesion within the bitumen mass, and bitumen viscosity, all contribute to the strength of asphalt.

MATERIAL PROPERTIESHorizontal and vertical modulus of unbound granular materials varies from each other (i.e., they are anisotropic). The vertical modulus of unbound granular materials is assumed to be twice the horizontal modulus in the mechanistic-empirical design approach. The vertical modulus of unbound granular materials is assumed to be twice the horizontal modulus in the mechanistic- empirical design approach.

The modulus of granular materials derived from laboratory repeated load triaxial testing at the materials in situ density, moisture content, and stress levels under a Standard Axle is the suitable value for pavement design. For estimating the modulus of the top granular sublayer, two procedures are advised, in order of preference: direct measurement and assigning presumptive values.

Modulus is measured in a triaxial cell under conditions of recurrent loading in Direct Measurement, which is the recommended method. The modulus is calculated using the recoverable fraction of the axial deformation response.

Because the moduli of unbound granular materials are stress sensitive and hence reliant on moisture and compaction levels in the roadbed caution should be exercised when using published data. When alternative, more accurate information is unavailable, the following Table might be used as a guide when assigning maximum values to granular materials under thin bituminous surfacing. The table: 02 shows values for two types of crushed rock of base quality: high standard and normal standard. The crushed rocks that are widely employed by road agencies are normal crushed rocks (Austroads part 02).

Table 02: Elastic properties unbound granular material (Austroads part 02)

The following tables, table number 03 and 04 provides moduli of top sublayer of a typical flexible pavement. These tables can be compared while choosing between base material of Normal and High standard according to their thickness and design requirement.

Table 03: Recommended Vertical modulus of a high-quality base material's top sublayer (Austroads part 02)

Table 04: Recommended Vertical modulus of a high-quality base material's top sublayer (Austroads part 02)

51608491974900

MATERIALS SELECTIONMaterials design is the process of selecting materials with certain properties for a specific use. It addresses the underlying qualities of materials and how they relate to the needs of specific applications. Selecting the right materials depends on material position, design life and environmental effects of the pavement.

To achieve these goals for a sustainable and ecofriendly pavement design, it is important to address all the phases of life cycle as shown in Figure 2, material life cycle process.

Factors influencing Material SelectionSeveral factors are responsible for influencing the material selection process. Some of the factors are discussed below:

Strength of Material: Pavement materials are classified according to their strength and elasticity. Flexural strength, CBR or compaction tests are carried out to measure material strength.

Modulus of elasticity, Poissons ratio and Stress parameters are the measure of elastic strength of materials.

Financial factor: Material price is the primary concern of material selection. Alternative scopes can be considered in material costing over the pavement design life. Material costing is also important to calculate initial costing of pavement construction. Additional costing is added if the materials are subjected to production transportation and storage facility. It also considers the upgradability, recycling, and pavement removal at the end of design span of the pavement.

Availability of materials: Not all materials for road construction are available locally. Therefore, before designing a pavement, it is important to know if the materials are available locally and thus selection is based on availability.

Experience of using materials: The road technologies are advancing day by day. Various materials are now being used to construct roads. But to use a new material in construction is risky when the workers are not experienced in using it.

Environmental interaction: Various materials are available for pavement construction. But these materials can be harmful if they interact with nature in a toxic way. For example: Groundwater contamination.

Pavement failure modelTraffic loads are distributed evenly by the tyres according to the tyre pressure. The imposed load first falls on the surface layer, causing horizontal tensile strain at the asphalt layer's bottom. Same follows for base layer. And subgrade experiences vertical compressive strain due to the applied load. Thus, there are 3 critical location of pavement failure as shown in figure 03.

fig 03: Critical location of pavement failure

The thickness of material layers plays a vital role for pavement failure. When load is applied at the surface, it gets transferred to subgrade. The stress generated due to the loading varies with the thickness of the layers. The more the thickness is, the greater the area becomes for the applied forces while travelling through subsequent layers. Hence, stress becomes less in magnitude as shown in fig 04.

Fig 04: Relationship between stress and thickness of pavement layers

PAVEMENT FAILUREThere are 2 common types of pavement failure.

1. Fatigue Failure: Fatigue failure occurs when an asphalt layer fails due to a horizontal tensile force created at the bottom of the layer. (fig 05). Overloading is responsible for fatigue failure.

Fig 05: Fatigue failure

2. Rutting Failure: The permanent depression developed in the pavement along the path where the wheels travel is called Rutting (fig 06). Asphalt layer compaction and shear failure cause Rutting failure. Compressive stress on the asphalt layer also contributes to Rutting failure.

Fig 06: Rutting failure

Literature ReviewVarious recycled materials can be used in pavement construction. Some of the promising materials are studied and reflected below:

Recycled Concrete AggregateRecycled concrete aggregates (RCA) has been used as a pavement material for a long time now. Because it has a far better potential for use as a construction material than many other recycled materials, the production of RCA is a fast-rising industry. Highways require large volume of aggregates. RCA is a good choice of crushed aggregates used in base layer of highways. Modulus of aggregates is an elastic property measured under dynamic stresses. RCA has got some physical features like particle sizes and compaction which give RCA high resilient modulus. As a result, more research into the performance characteristics of RCA is needed to determine their behaviour in the base and sub-base courses of pavements. The RLT test (repeated load tri-axial) is the recommended laboratory scale test for evaluating the performance of pavement materials through elastic and plastic deformation characteristics under various moisture content and stress circumstances with respect to repetitive loads. Moisture sensitivity was recorded good. The resilient modulus of the compacted recycled concrete was found to be 233-247 MPa and for base materials of good quality it was 275-450 MPa (Jayakody, S., Gallage, C. and Ramanujam, J., 2019).

Super Hard Asphalt (SHA)The by-product of the direct coal liquefaction process, which creates clean liquid fuels from coal and is one of the clean-coal technologies, is super hard asphalt (SHA). At room temperature, it is a black, solid substance. At room temperature, SHA is a dark-coloured solid that makes up around 30% of the entire coal utilised as a feedstock. According to the definition of asphalt, SHA is an asphaltic material with a softening point greater than 180C and a penetration depth of less than 5mm at 25C, making it harder than conventional hard petroleum asphalt. SHA has a density that is higher than petroleum asphalt and hard asphalt but is within the TLA range. The ash content of SHA and TLA is larger than that of petroleum asphalt and hard asphalt. The nitrogen concentration of SHA is higher than that of TLA, and the nitrogen is mostly in the form of pyridine, pyrrole, and indole, all of which are polar molecules that help SHA adhere to aggregates. When it comes to mixing and paving asphalt on the road, volatility is always a problem. Unfortunately, no comparable specification exists for asphalt's volatility. SHA has a volatilisation of only 0.02 percent, whereas petroleum asphalt has 0.79 percent and TLA has the highest volatilisation of 3.36 percent, which is almost 170 times that of SHA. High temperature performance, reduced volatiles, extremely hard and stiff, good adherence to aggregates, and good filler filling factor due to high proportion of ultrafine insoluble particles, which allows for less asphalt to be used as a binder. In-situ micro-crosslink technology fixes poor low temperature and ductility performance; compatibility and softening technology fixes greatest softening point and lowest penetration; unique shear mixing technology fixes probable insoluble particle aggregation inside SHA. In 2016, two SHA-based asphalt scale-up experiments and test road pavements were successfully completed. The features of SHA, as a new pavement material, are promising for future application development (Wei, J., Zhang, S., Sheng, Y., Gong, X., Chen, C. and Jow, J., 2020.).

RCA and Steel SlagMineral aggregates and asphalt binder make up hot-mix asphalt (HMA) mixes, which are complicated substances. In asphalt pavement, the aggregate serves as a structural framework, while the asphalt binder serves as birdlime. Aggregates contribute 95% of the weight and 75 to 85 percent volume of HMA. Physical features of the aggregates and filler also contribute to road performance to a great extent. There are various types of wastes mainly categorized into 4 categories: Municipal, C&D, Industrial and Mining wastes. These huge quantities of wastes could be used in different sectors of construction sectors. Here, the authors presented RCA and steel slag to be used as aggregate substitute.

Steel making process creates steel slag which is a synthetic aggregate as a byproduct. During the steel making process around 15 to 20 percent steel slag is produced. Steel slag has angular shape. It can only be used as fine aggregates. Furthermore, not all slags can be utilised as aggregates: some slags, for example, contain substantial levels of free magnesia and lime, both of which expands in humid condition. Such swelling can cause pavement cracking.

Construction debris from demolition and construction operations accounts for a significant component of solid waste. RCA is recovered in huge quantities from construction wastes (75%), demolition wastes (70%), renovation (70%) and typical civil sectors (40%). The use of RCA instead of coarse dacite aggregates in asphalt concrete mixtures has a negative impact on the material's mechanical qualities. Because of the effects of mixing and compression on the RCA particles, they become faint. Hence, the mechanical characterstics of RCA-containing mixes were found unsatisfactory. In dynamic creep test, the best composition was found when

Steel slag and RCA were used as coarse and fine aggregates respectively. This combination reduced permanent deformation up to 40% (Arabani, M. and Azarhoosh, A., 2012).

Fig 7: Steel slag performance under various loadings (Maghool et al., 2019)

The resilient modulus values of the samples were consistent according to local authority in Australia for typical quarry material for roadwork applications (125300 kPa) (Arulrajah et al., 2013).

Marble quarryAbout 95% of wight of asphalt roads is made up by aggregates. Aggregates are often sourced from local aggregate quarries or natural aggregate sources. Construction and marble manufacture are two of the most waste-producing sectors. During the mining, processing, and polishing processes, the squandered amount of the minerals is about 70%. The processing work, which accounts for around 30% of the weight of the marble blocks, is ground up and deposited into riverbeds, endangering aquifer porosity. Nearly 40% of the trash generated during quarrying activities (86, 000 m3 per year) form rock pieces of various sizes, which get deposited in neighboring lowlands, roads, riverbeds, causing widespread pollution. The resulting rock fragments can be used in pavement construction as aggregates. According to Zoorop and Suparma, the construction of pavements consumes up to 12,500 tonnes of fresh aggregates each kilometre.

The goal of this paper is to look into the use of waste marble pieces as aggregates in the asphaltic mix design process, which are formed in the process of marble block production and cutting. The utilization of leftover marble aggregates in road construction has the potential to save money while also promoting environmental protection.

Marshall stability and Standard pavement aggregates test are performed to compare the waste marble properties and andesite aggregates against control aggregate samples. This investigation included four types of aggregates: Sample A (Waste Marble), Sample B (Andesite) and Sample C (Limestone) and Sample D (Limestone).

Sample A's (Waste Marble) abrasion loss was 27.44% which meets specification limits, but the Aggregate Impact Value (AIV) was 18.66% which exceeds the 18% capping, as per the Los Angeles abrasion test results. Sample D (Distinct Limestone) had an AIV score of 18.60 percent. In Afyonkarahisar, different pavement sections like wearing, binder and surface dressing all use Sample D. From various tests, it was deducted that marble quarries are good enough for binder coarse aggregates. (Akbulut, H. and Grer, C., 2007).

Fig 8: Modulus of marble under various stresses

In the tri-axial cyclic loading test, for a stress of 10MPa, a sample of marble showed a modulus of 91.06 MPa (Yang, Tian and Ranjith, 2017).

RFAP (RECYCLED FINE AGGREGATE POWDER)Construction wastes mark a huge quantity in total waste generation. These wastes mainly include RCA, Cement, Bricks. RCA has been being used as a coarse aggregate in construction industry. When RCA is produced, a huge quantity of fine powder is also produced as by product. It is called RFAP.

The aggregates used in asphalt mixtures contain filler, which is a necessary component. Its presence is crucial in influencing the qualities of combinations based on its characteristics. Many experts have been looking into different waste powders that can be used to replace mineral filler in asphalt mixtures. They discovered that waste powders (such as fly ash, lime) had no negative impact on asphalt mixtures and can even increase its engineering properties. As a result, using fine waste pebbles and powder as a filler in asphalt mixtures could be a cost- effective and efficient solution. The purpose of this article is to look at the possibility of employing RFAP made from fine waste aggregates as a filler in an asphalt mix.

A series of laboratory tests have been conducted to determine the efficacy of recycling waste fine aggregates as RFAP in asphalt mixtures.

The tests shows that the powder was composed of silicate and calcite. In comparison to lime powder, RFAP has lower calcium and higher silicon in composition. The use of RFAP as a filler can increase the asphalt mixture's water sensitivity, high-temperature characteristics, and fatigue life. RFAP, on the other hand, may produce a little reduction in the low-temperature performance of asphalt mixtures. RFAP improves asphalt mixture properties.

Recovered Crushed Glass (RCG)Glass has been used in mix with aggregates in pavement construction for some time now. Use of RCG is a sustainable way to minimise cost and helping the environment to get rid of trash materials. Lots of glass products are thrown in the sea and landfill. A portion only gets recycled. In New Zealand, glasses (40mm sizes and 5% mix) were used to build roads and to date it the pavement performance is good. The crews were happy to work with RCG as it was easy.

Lab tests were carried out and results were satisfactory and were in favour of RCG as shown in table 05.

Table 05: Aggregate properties with and without glass

On a roadway upgrade project for Nelson City Council, a product containing 5% recycled glass was tested. Brook Street was upgraded to a dual carriageway rural/residential road with a total length of 1.42 kilometres. 140 m portion of the 1.42 km was constructed with a base coarse aggregate containing 5% glass (chainage 1060 m to 1180 m).

Brook Street is a busy street with a moderate volume of traffic, about 300 vehicles passes through it per day. The granular pavement was 200mm thick with a two-coat chip seal on top.

Prior to applying the chip seal surfacing, the site was subjected to Benkelman Beam rebound deflection testing. The average deflections of the base coarses were 0.96mm and 0.98mm for zero and five percent of glass section respectively. The presence of glass in the pavement construction is undetectable by the Benkelman Beam test since the findings are statistically equal.

The deflection findings are shown in the graph below, with 0% glass data in blue and 5% glass data in red as shown in fig 07:

Fig 09: Deflection of 0 and 5 percent glass content

A visual comparison of performance so far shows no difference between sections of road made using recycled glass and sections constructed with virgin aggregate. Neither shows any signs of rutting or fatigue.

Fig 10: Modulus of Coarse aggregate and glass blend

A mix of 25% of recycled glass and 75% fraction of limestone gives a modulus of 350 MPa (Mohsenian Hadad Amlashi, Vaillancourt, Carter and Bilodeau, 2018).

Table 6: Mechanical Properties of pavement material

Recycled Materials Modulus (MPa)

RCA 233-247

Steel slag 125-300

Marble Quarry 91.06

RCG 350

Research Gaps and QuestionsA lot of studies have been done on recycle materials on pavement structure. But very few studies have been on the combination of different materials for pavement construction.

Based on literature review and the current practices of pavement design, the proposed research project will address the following questions:

What are the most suitable combinations of materials (including recycled materials)?

Are the proposed combinations of pavement structure economically and environmentally suitable?

The effects of placement of materials on pavement performance combinations

CONCLUSIONRecycled materials have been being used in road construction for some time now. They have huge potential in building and construction sector. The literature review done above found out the availability and use of various recycled materials in pavement construction. The modulus of them have been found out too. Now it is required to know the best suitable combination of these materials, find out environmental compatibility along with economic benefits and checking the performance of the newly constructed pavement built with recycled materials. Further research is required for the above-mentioned quarries.

PROJECT TIMELINE2022 Weeks

Activity 1 2 3 4 5 6 7 8 9 10 11 12 13

Literature review 15990624820017196651156 Finalization of methodology 113832292512 Data collection 124209172364 Data Analysis 118605167619 Write final Report 91098202635 REFERENCEAkbulut, H. and Grer, C., 2007. Use of aggregates produced from marble quarry waste in asphalt pavements. Building and Environment, 42(5), pp.1921-1930.

Arabani, M. and Azarhoosh, A., 2012. The effect of recycled concrete aggregate and steel slag on the dynamic properties of asphalt mixtures. Construction and Building Materials, 35, pp.1-7.

Ashteyat, A., Obaidat, A., Kirgiz, M. and AlTawallbeh, B., 2021. Production of Roller Compacted Concrete Made of Recycled Asphalt Pavement Aggregate and Recycled Concrete Aggregate and Silica Fume. International Journal of Pavement Research and Technology.

Austroads.com.au. 2022. Guide to Pavement Technology Part 2: Pavement Structural Design. [online] Available at: <https://austroads.com.au/publications/pavement/agpt02> [Accessed 22 April 2022].

Busari, A., Adeyanju, E., Loto, T. and Ademola, D., 2019. Recycled Aggregate in Pavement Construction: Review of Literatures. Journal of Physics: Conference Series, 1378(2), p.022026.

Chen, M., Lin, J. and Wu, S., 2011. Potential of recycled fine aggregates powder as filler in asphalt mixture. Construction and Building Materials, 25(10), pp.3909-3914.

Jayakody, S., Gallage, C. and Ramanujam, J., 2019. Performance characteristics of recycled concrete aggregate as an unbound pavement material. Heliyon, 5(9), p.e02494.

Maghool, F., Arulrajah, A., Suksiripattanapong, C., Horpibulsuk, S. and Mohajerani, A., 2019. Geotechnical properties of steel slag aggregates: Shear strength and stiffness.Soils and Foundations, 59(5), pp.1591-1601.

Mohsenian Hadad Amlashi, S., Vaillancourt, M., Carter, A. and Bilodeau, J., 2018. Resilient modulus of pavement unbound granular materials containing recycled glass aggregate.Materials and Structures, 51(4).

Wei, J., Zhang, S., Sheng, Y., Gong, X., Chen, C. and Jow, J., 2020. Super hard asphalt (SHA) from direct coal liquefaction process as pavement material. Journal of Cleaner Production, 274, p.123815.

Yang, S., Tian, W. and Ranjith, P., 2017. Experimental Investigation on Deformation Failure Characteristics of Crystalline Marble Under Triaxial Cyclic Loading.Rock Mechanics and Rock Engineering, 50(11), pp.2871-28