Sustainability of Concrete Roads by Using Reclaimed Asphalt Pavements

*Tayfun Uygunoğlu, İlker Bekir Topçu and Aytaç Ünverdi* 

#### **Abstract**

 The reuse of reclaimed asphalt pavement (RAP) instead of aggregate reduces natural aggregate consumption in concrete mixtures and production cost of concrete. Waste crushed asphalt's water absorption is less than the water absorption of natural aggregate owing to the bituminous structure; this reduces the water demand in fresh concrete. In the present study, the optimal use of RAP particles as aggregate in concrete roads has been measured. In the tests, concrete specimens have been produced with 0–12 mm waste crushed asphalt at the replacement ratios of 0, 25, 50, and 100%. The destructive, nondestructive, and durability tests have been carried out on hardened and fresh concrete specimens to identify physical and mechanical properties. The slump values were obtained in fresh concrete and ultrasonic pulse velocity (UPV), and compressive strengths were obtained in concrete at the end of 3, 7, and 28 days. According to experimental results, asphalt waste caused the reduction of strength, physical, and mechanical properties.

**Keywords:** reclaimed aggregate, waste, recycle, concrete road, crushed asphalt

#### **1. Introduction**

 Roads have an important role in infrastructure departments of any nations. Roads consume large amounts of energy because of their construction and maintenance phases also for the vehicles which travel on them. This consumption increases the atmospheric emissions, reduces the nonrenewable resources, and effects other environmental changes [1]. Any reduction of the energy consumption related to road building, even just by a small percentage, is going to have remarkable constructive inferences for sustainable urban development. Approximately 98% of roads are built as asphalt pavement in Turkey. Wearing asphalt pavement layers are generally removed during resurfacing, reconstruction, or rehabilitation operations. By removing and processing the asphalt, obtained material after removing becomes reclaimed asphalt pavement (RAP), which comprises substantially aggregate and asphalt binder (**Figure 1**) [2, 3].

On the other hand, using concrete is more durable and safer at road construction technology. They are considerably less inclined to tear and wear defects like stripping, cracking, rutting, loss of texture, and pothole. Concrete pavement's principal advantage is low maintenance requirement. Some well-designed concrete

#### **Figure 1.**

*A view of reclaimed asphalt pavement.* 


#### **Table 1.**

*Compressive strength values for concrete roads depending on using area [5, 6].* 

pavements not require any heavy maintenance for their life of 40 years [4]. Less maintenance also means fewer traffic delays and an advantage on some of the already congested highways. **Table 1** shows compressive and flexural strength suggestions to build concrete roads related to using areas. The compressive strength value of concrete road for highway is given as 37 MPa at least [5, 6].

 The environmental impacts of the construction industry are very huge concerning waste product, material use, and energy use. Infrastructure construction and highway design within the construction industry are one of the biggest material consuming industries throughout the world. Besides, reclaimed asphalt pavement (RAP) is a frequently used recycled material in the world. In recent researches [7–9], in order to produce hot mix asphalt (HMA) mixtures, RAP replacement with proportions above 50% is mentioned to be feasible while providing satisfactory mechanical properties. RAP is most commonly used as a virgin asphalt binder substitute and an aggregate in recycled asphalt paving, but it is also used as a stabilized base aggregate, granular base or sub-base, and embankment or fill material. The main objective of this study is to evaluate the sustainability of roads by using 100% recycled asphalt materials for rehabilitation and construction.

#### **2. Experimental studies**

#### **2.1 Materials used**

Ordinary portland cement (OPC) was preferred with a minimum strength of 45 MPa at 28 days (CEM I 42.5 R) in the experiments. It is according to the European Standards E 197-1. **Table 2** shows the characteristic properties of related cement. Calcareous stone as crushed stone I (CS I) in 6–12 mm and crushed stone


#### *Sustainability of Concrete Roads by Using Reclaimed Asphalt Pavements DOI: http://dx.doi.org/10.5772/intechopen.87836*

#### **Table 2.**

*Characteristics of OPC.* 


#### **Table 3.**

*Material component per cubic meter.* 

II (CS II) in 12–22 mm is used as coarse aggregate. The specific gravity of coarse aggregates is 2.70 and 2.71, respectively. Crushed stone sand (CSS) was used as fine aggregate with specific gravity of 2.57, in 0–6 mm.

The RAP was obtained from the asphalt construction site of Afyonkarahisar. The specific gravity of RAP was 2.6.

#### **2.2 Concrete mix design**

 Chemical admixture content, cement dosage, and water cement ratio are designed as 1.0% (by weight of cement), 350 kg/m3 , and 0.45 lt/kg in concrete specimen mixtures. Aggregate volume was used to establish the aggregate weight. RAP was added to the concrete specimen mixtures instead of the total of CSS and CS-I used in the concrete by 25, 50, and 100%. **Table 3** shows the mixture proportion for per cubic meter of concretes.

After the concrete production, the slump test was performed by Abrams cone. The concrete was then poured into molds with dimensions of 150 × 150 × 150 mm

 and de-molded after 24 h. They were cured until 7 and 28 days in water under standard conditions. After the curing process, compressive strength and flexural strengths were determined. In addition, ultrasonic pulse velocity (UPV) test was also performed according to ASTM C597-16 [10].

#### **3. Results and discussions**

 The slump test is carried out to explore and to check the workability of fresh concrete, consequently the ease with which concrete flows. In addition, it can be used as an indicator of a consistency of fresh concrete. The slump values of RAP containing concrete are presented in **Figure 2**. The slump of the control mixes (0% RAP) was 60 mm. The higher slump was obtained with comparable quantities of free water.

When slump value is 65 mm for 25% of RAP content, it is 75 mm for the 100% RAP-containing fresh concrete. It is emphasizing that the water requirement for a given slump is lower of RAP aggregates than crushed limestone due to asphalt residue on the RAP. Asphalt residues repel the surface water due to polymeric structure, and aggregate does not absorb the mixing water from their surface. In other words, using of RAP in concrete increases the workability of fresh concrete.

**Figure 2.**  *Consistency of RAP containing concrete.* 

**Figure 3.**  *Compressive strength values of RAP containing concretes.* 

*Sustainability of Concrete Roads by Using Reclaimed Asphalt Pavements DOI: http://dx.doi.org/10.5772/intechopen.87836* 

**Figure 3** shows the various mixtures with compressive strengths for ages of 3, 7, and 28 days. Loss of strength of 26–59.4% was observed in recycled concrete, which is made with RAP. There was a maximum reduction in the concrete made from 100% of RAP containing concrete at 28 days. The adhesive of cement matrix and RAP in the concrete was relatively weak due to asphalt residue, and the effect of the crushing age was more restrained. However, according to **Table 1**, the mentioned values are inside of a reasonable range.

All the RAP concrete has different using areas depending on RAP content. For example, when the 25% of RAP concrete is proper for using in heavy traffic, 50% of RAP concrete can be used in normal traffic, and 100% of RAP can be used in local traffic or parking area concrete for recycling.

The use of RAP as recycled aggregates also causes a decrease in the flexural strength of the concrete as shown in **Figure 4**. The reduction was in ratio of 44, 48, and 50% for 25% RAP, 50% RAP, and 100% RAP concrete, respectively. Again, when the flexural strength values are considered, according to ranges shown in **Table 1**, it is clear that 25% of RAP concrete can be used in normal traffic and 50 and 100% of RAP concrete can be used in local traffic and parking area (**Figure 4**).

 Ultrasonic pulse velocity (UPV) and nondestructive ultrasonic pulse velocity (UPV) tests have been performed on 3-, 7-, and 28-day aged cube samples [10]. Higher UPV means high quality of concrete and durability. The UPV values that were measured on all types of concrete specimens were examined (**Figure 5**), and it

**Figure 4.**  *Flexural strength values of RAP containing concretes.* 

**Figure 5.**  *Ultrasonic pulse velocity (UPV) of RAP-containing concretes.* 

**Figure 6.**  *Dynamic E-Moduli of RAP containing concretes.* 

**Figure 7.**  *SEM image of RAP in concrete.* 

was observed that the UPV values decreased by an increase of the RAP using ratio. UPV can be evaluated as an indicator of the amount of pore medium in the concrete [11]. For this reason, it is clear that the RAP concretes include a small amount of space. If UPV values are higher than 4 km/s, this means the concretes are classified as high-quality concrete.

The modulus of elasticity (E-Moduli) of concrete depends on the type and content of aggregates, the modulus of elasticity of the hydrated cement matrix, the volume of the binding materials, and the water-to-binder ratio [12, 13]. It is a key factor for estimation of deformation and stiffness of the structures. Furthermore, the precise determination of the modulus of concrete elasticity is essential for structures, which require strict deformability control [14]. Relatively low values of modulus of elasticity (Ec) were obtained for the tested concretes (**Figure 6**) in RAP recycled concrete when compared to reference concrete. Values of elasticity dynamic modulus varied from 51 to 39 GPa for RAP including concrete.

 To define the surface properties of RAP, scanning electron microscope (SEM) imaging was carried out (**Figure 7**). It can be clearly seen that when aggregate surface is rough, it has smooth surface after asphaltic coating [15]. The asphalt coating of aggregate surface makes the concrete more workable but with weaker adhesion of cement matrix than the reference concrete.

*Sustainability of Concrete Roads by Using Reclaimed Asphalt Pavements DOI: http://dx.doi.org/10.5772/intechopen.87836* 

### **4. Conclusions**

The strength of concrete including 100% recycled aggregates instead of natural aggregate was less than the concrete including natural aggregates with the same water-to-cement ratio:


Consequently, the distances between the material source and the construction site add an additional burden on construction costs. RAP can reduce the required transportation costs for natural aggregates by evaluating them in mobile concrete plants, which can be found near to the construction site after being broken at the desired dimensions. As a result, it has been concluded that in terms of compressive and flexural strength, it provides the limit values recommended in the specifications up to 100% and therefore can be used in concrete road construction.

#### **Author details**

Tayfun Uygunoğlu1 , İlker Bekir Topçu2 and Aytaç Ünverdi3 \*

1 Department of Civil Engineering, Afyon Kocatepe University, Afyon, Turkey

2 Department of Civil Engineering, Eskişehir Osmangazi University, Eskişehir, Turkey

3 Eskişehir Metropolitan Municipality, Eskişehir, Turkey

\*Address all correspondence to: unverditr@yahoo.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

### **References**

[1] Mhlongo SM, Abiola OS, Ndambuki JM, Kupolati WK. Use of recycled asphalt materials for sustainable construction and rehabilitation of roads. In: International Conference on Biological, Civil and Environmental Engineering (BCEE-2014) 17-18 March, 2014 Dubai, UAE

[2] Huang B, Shu X, Li G. Laboratory investigation of Portland cement concrete containing recycled asphalt pavements. Cement and Concrete Research. 2005;**35**:2008-2013

[3] Decker D. State of the practice for use of RAP in hot mix asphalt. Journal of the Association of Asphalt Paving Technologists. 1997;**66**:704

[4] Nagataki S, Gokce A, Saeki T, Hisada M. Assessment of recycling process induced damage sensitivity of recycled concrete aggregates. Cement and Concrete Research. 2004;**34**:965-971

[5] Topcu İB, Isıkdağ B. Utilization of reclaimed asphalt pavement instead of aggregates for. Concrete TCMB Turkish Cement and Concrete World. 2006;**11**:72-85

 [6] Rezende LR, Silveira LR, Araújo WL, Luz MP. Reuse of fine quarry wastes in pavement: Case study in Brazil. Journal of Materials in Civil Engineering. 2014;**26**(8):1-9

[7] Reyes O, Camacho J. Informe Proyecto ING-730 evaluation of hot mix asphalt mixtures with replacement of aggregates by reclaimed asphalt pavement (RAP) material SIIV—5th international congress—sustainability of road infrastructures. Procedia— Social and Behavioral Sciences. 2012;**53**:379-388

[8] Pereira P, Oliveira J, Picado-Santos L. Mechanical characterization of hot mix recycled materials. International

Journal of Pavement Engineering. 2004;**5**(4):211-220

[9] Celauro C, Benardo C, Gabriele B. Production of innovative, recycled and high-performance asphalt for road pavements. Resources, Conservation & Recycling. 2010;**54**(6):337-347

[10] ASTM C597-16, Standard Test Method for Pulse Velocity through Concrete. West Conshohocken, PA: ASTM International; 2016. Available from: www.astm.org

[11] Yasar E, Erdogan Y, Kılıç A. Effect of limestone aggregate type and water cement ratio on concrete strength. Materials Letters. 2004;**58**(5):72-777

 [12] Uygunoğlu T, Topçu İB, Çelik AG. Use of waste marble and recycled aggregates in self-compacting concrete for environmental sustainability. Journal of Cleaner Production. 2014;**84**:691-700

[13] Shkolnik I. Effect of nonlinear response of concrete on its elastic modulus and strength. Cement and Concrete Composites. 2005;**27**:747-757

[14] Valdés G, Pérez-Jiménez F, Miró R, Martínez A, Botella R. Experimental study of recycled asphalt mixtures with high percentages of reclaimed asphalt pavement (RAP). Construction and Building Materials. 2011;**25**(3):1289-1297

[15] Ryu JS. An experimental study on the effect of recycled aggregate on concrete properties. Magazine of Concrete Research. 2002;**54**(1):7-12

#### **Chapter 27**
