- Email: [email protected]
Utilization of recycled brick powder as alternative filler in asphalt mixture
Construction and Building Materials 25 (2011) 1532–1536
Contents lists available at ScienceDirect
Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat
Utilization of recycled brick powder as alternative filler in asphalt mixture Mei-zhu Chen a, Jun-tao Lin a, Shao-peng Wu a,⇑, Cong-hui Liu b a b
Key Laboratory of Silicate Materials Science and Engineering, Wuhan University of Technology, Ministry of Education, Wuhan 430070, PR China Shanxi Provincial Research Institute of Communication, Taiyuan 030000, PR China
a r t i c l e
i n f o
Article history: Received 4 May 2010 Received in revised form 26 July 2010 Accepted 23 August 2010 Available online 25 September 2010 Keywords: Asphalt mixture Filler Recycled brick powder Properties
a b s t r a c t The objective of this study is to investigate the use of recycled brick powder as replacement of mineral filler in asphalt mixture. A comparative study was carried out on the performance of two mixtures using recycled brick powder and limestone filler. The experimental performed were indirect tensile tests, static and dynamic creep tests, water sensitivity tests and fatigue tests. The results show that the mixtures prepared with recycled brick powder have better mechanical properties than the mixtures with limestone filler. Thus, it is promising to use recycled brick powder as mineral filler in asphalt mixture. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction About 90% highways in China are asphalt concrete pavements. The construction and maintenance of these pavements require large amounts of aggregates and mineral fillers, which typically account for nearly 95% of the asphalt concrete. The increase of civil infrastructures has led to a fast decrease of available natural resources, and seeking for other alternative is crucial. Recycling aggregates or fillers from the construction and demolition (C&D) waste is a preferable one. It is not only economically viable but also environmental friendly. At present, the total amount of C&D waste accumulated in China is estimated as 7000 million tons, and the annual amount of C&D waste due to building backout and construction is 200 million tons and 100 million tons respectively. Moreover, the amount of C&D waste is increasing in the rate of 10% every year. Brick is the largest component of C&D waste due to the traditional building habits and old-line production technology [1]. It is reported that around 20,000 million m3 clay bricks have produced in the past 50 years in China, most of which would be demolished in the later 50 years. Traditionally, waste bricks consumption is mainly disposed as soil conditioner or land filling. In recent years, reusing them as civil engineering materials has been brought into effect. Even if the combination of bricks constitutes a large portion of the C&D wastes, the using of waste brick aggregate is prohibited in Hong Kong [2]. A number of researches still have been done to ⇑ Corresponding author. Tel./fax: +86 27 87162595. E-mail addresses: [email protected] (M.-z. Chen), fl[email protected] (J.-t. Lin), [email protected] (S.-p. Wu), [email protected] (C.-h. Liu). 0950-0618/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.conbuildmat.2010.08.005
evaluate the potential use of crushed bricks as concrete aggregate, and some published reports indicates that the composition of crushed brick has considerable influence on the mechanical performance of concrete [3–5]. However, it seems that the use of bricks as concrete aggregate can not be widely applied. Waste bricks are applied as powder materials in some countries and areas. The demolished bricks are burned into slime burnt ash in Japan and are commonly crushed to form filling materials in Hong Kong [6]. In Italy, Corinaldesi et al. [7] evaluated the possibility of using brick powder as cementitious material replacing Portland cement, and they found out that the mortars containing bricks powder show good performance. Naceri and Hamina [8] also investigated the use of waste brick powder as a partial replacement for cement in the production of cement mortar, and confirmed the potential use of this waste material to produce pozzolanic cement. But until recently, there are few reports about using waste brick in asphalt mixture in the literatures. However, many researchers have been investigating other waste powders to replace the mineral filler in asphalt mixture. Ahmed and Othman [9] investigated the effect of using waste cement dust as mineral filler on the mechanical properties of asphalt mixture, and the results indicated cement dust can totally replace limestone powder in asphalt paving mixture. Tapkin [10] evaluated the effect of fly ash as a filler replacement on the mechanical properties of asphalt mixture and found that fly ash can be used effectively in a dense-graded wearing course as a filler replacement. Hwang et al. [11] investigated the potential use of waste lime as mineral filler in asphalt mixture, and the results suggested that using waste lime as mineral filler can improve the permanent deformation characteristics, stiffness and fatigue
1533
M.-z. Chen et al. / Construction and Building Materials 25 (2011) 1532–1536
endurance of asphalt mixture. Based on these researches above, the use of such waste powders as filler in asphalt mixture not only has no negative influence on asphalt mixture, but also can improve its engineering characteristics. Therefore, recycling waste bricks as filler for asphalt mixture may be an economic way in road and construction engineering, which can enlarge the application range and improve the utilization rate of C&D waste. This paper investigates the mechanical properties of asphalt mixtures using brick powder as mineral filler, and various tests including indirect tensile strength and modulus, static and dynamic creep and fatigue tests are conducted to evaluate the properties of asphalt mixtures. Based on these experimental results, the feasibility of waste brick powder as mineral filler in asphalt mixture is assessed comparing with control mixture using conventional limestone filler. 2. Materials and experiments 2.1. Materials
Table 3 Chemical composition of brick powder and limestone powder, %by mass. Component
Recycled brick power
Limestone powder
SiO2 CaO Al2O3 Fe2O3 MgO K2O Na2O TiO2 SO3 P2O5 MnO ZrO2 SrO ZnO BaO Cl LOI
68.10 2.05 16.35 6.04 1.43 2.38 1.20 0.85 0.11 0.26 0.06 0.05 0.02 0.03 0.07 0.00 0.80
17.95 46.90 0.46 0.52 3.64 0.10 0.08 0.03 0.02 0.04 0.14 0.11 0.02 0.01 0.02 0.00 29.95
Total
99.80
99.99
2.1.1. Asphalt binder One type of asphalt binder with normal paving grade 60/70 (AH70) was used to produce all test specimens in this study. This asphalt binder, which had a penetration of 65 (0.1 mm at 25 °C, 100 g and 5 s), ductility of 167.3 cm (at 15 °C) and softening point of 45.4 °C, was supplied by Koch Asphalt Co. Ltd., in Hubei Province, China. 2.1.2. Aggregate The basalt Aggregate used in this study was obtained from Jinmen, Hubei Province, China. And Table 1 gives the basic physical properties of basalt aggregate. In this study, four different sizes of crushed basalt aggregate were used, and they were 9.5–16, 4.75–9.5, 2.36–4.75 and 0–2.36 mm, respectively. 2.1.3. Filler Recycled bricks were obtained from the demolition building in Wuhan, China, which had nearly 20 years history. These clay bricks were washed with water, and then dried at 80 °C for 10 h. Finally, the recycled bricks were crushed by jaw crusher and ground by ball mill for 15 min to recycled brick powder. Limestone filler was used as the control sample. The basic properties of fillers were given in Table 2. The chemical and mineralogical compositions of fillers were given in Table 3 as measured by X-ray fluorescence (XRF). It can be seen in Table 3 that CaO, SiO2 and Al2O3 were typical constituents of these fillers, and limestone powder had considerable higher CaO content while brick powder had higher SiO2 content. The microscopic morphology of recycled brick powder and limestone powder were shown in Figs. 1 and 2 as measured by Scanning Electron Microscopy (SEM), respectively. It could be seen from these SEM results that the surface of recycled brick powder was much rougher and its particle distribution was more homogenous than that of limestone powder, which indicated the recycled brick powder has higher adsorption than limestone filler. Additionally, the draindown tests according to AASHTO T-305 and specific surface area tests were used to verify the high absorption of recycled brick powder. Draindown tests can reflect the content of free-asphalt in mixtures and the lower drainage value means the higher
Table 1 Basic properties of basalt aggregate in this test. Property
Measured values
Standard
Specific gravity (g/cm3) Water absorption ratio (%) Abrasion loss (%) Frost action (%)
2.719 0.82 13.6 0.64
ASTM ASTM ASTM ASTM
C-127 C-127 DC-131 C-88
Table 2 Basic properties of mineral filler in this test. Test items
Recycled brick powder
Limestone powder
Passing (%)
100.0 98.6 92.3 2.710 1.0 0.48
100.0 97.2 91.3 2.768 0.9 0.67
0.6 mm 0.3 mm 0.075 mm Specific gravity (g/cm3) Absorption (%) Hydrophilic coefficient
Fig. 1. SEM morphology of recycled brick powder.
absorption of powder in this test. Moreover, higher specific surface area also means higher absorption of powders. The tests results showed that the drainage value of the mixtures with recycled brick powder and limestone powder were 2.8 103 and 1.8 103, respectively, and the specific surface area of recycled brick powder and limestone powder were 446.8 cm2/g and 393.1 cm2/g, respectively. Therefore, the recycle brick powder has higher absorption than that of limestone powder. 2.1.4. Mixture deign and preparation In this study, aggregate grading curves for asphalt mixtures were obtained from China Highway Construction Specifications. Sieve analyses were carried out and available grading curve for the aggregate used in the study was shown in Fig. 3. Two types of fillers were used to produce mixture with the same aggregate and similar aggregate gradations. Marshall tests were carried out to find the optimum asphalt binder content of mixtures. The optimum asphalt binder content of asphalt mixture with recycled brick filler and limestone filler was 5.0% and 5.1% by weight of aggregate, respectively, and the mineral filler content of both asphalt mixtures was 4.0% by weight of aggregate. 2.2. Laboratory experiments 2.2.1. Indirect tensile modulus tests According to AASHTO TP31-standard test method for resilient modulus of asphalt mixture, the specimens with 63.5 mm in thickness and 101.6 mm in diameter were prepared and the resilient modulus of specimen was tested at the temperatures of 5 °C, 25 °C and 40 °C in order to understand insightfully the effect of temperature on the mixture. The test mode was under the assumed Poisson ration of 0.3, 0.35 and 0.4 for the different temperature 5 °C, 25 °C and 40 °C, respectively. 2.2.2. Water sensitivity tests AASHTO T-283 test was commonly used to evaluate the water sensitivity of asphalt mixtures. The specimen of 101.6 mm in diameter and 63.5 mm in height were prepared and then tested under the freeze–thaw cycles at the temperature between 18 °C and 60 °C. The indirect tensile strength of the conditioned and uncondi-
1534
M.-z. Chen et al. / Construction and Building Materials 25 (2011) 1532–1536
Fig. 2. SEM morphology of limestone powder. Fig. 4. Indirect tensile modulus of asphalt mixtures with different fillers.
pated energy. The failure of the flexural fatigue test could be defined as a 50% reduction in initial stiffness, which was measured from the center point of the beam after the 50th load cycle.
3. Results and discussion 3.1. Indirect tensile modulus
Fig. 3. Grading curves of aggregates.
tioned specimens was tested at 25 °C with the loading rate of 50 mm/min. Water sensitivity of mixture can be evaluated using the tensile strength ratio (TSR) value as follows:
TSR ¼ TS1 =TS2
ð1Þ
where TS1 is the average tensile strength of conditioned specimen, MPa; TS2 is the average tensile strength of unconditioned specimen, MPa.
2.2.3. Static and dynamic creep tests The static creep tests were carried out using Universal Testing Machine (UTM) to apply constant axial stress to asphalt specimens. The specimens of 100 mm in diameter and 100 mm in height were prepared and then tested at 60 °C. A stress of 100 KPa was applied on the specimens for 3600 s, then the load was removed and the deformation recovery was monitored for 5400 s. The accumulated microstrain was calculated as the ratio of the measured deformation to the initial specimen height according to the following equation:
e ¼ h=H0
ð2Þ
where e is the accumulated microstrain occurred in the specimen during a certain loading time at a certain temperature, 106 mm/mm; h is the axial deformation, mm; and H0 is the initial specimen height, mm. The dynamic creep tests were carried out using UTM to apply repeated axial stress pulse to asphalt specimens. The specimens of 100 mm in diameter and 100 mm in height were prepared and also tested at 60 °C. A haversine wave stress pulse was applied on the specimens for 10,000 s with frequency of 1 Hz (by allocating 100 ms for pulse width and 900 ms for rest period), and the test will be terminated when the accumulative stain reached 30,000 microstrain. The maximum axial stress was 100 KPa. During the test, the vertical deformation can be measured and the accumulated microstrain also can be calculated by the Eq. (2).
2.2.4. Fatigue tests The flexural beam test was conducted to evaluate the fatigue life of asphalt concrete at a temperature of 20 °C. According to AASHTO T-321, the beam specimens of 381 mm in length, 50.8 mm in thickness and 63.5 mm in width were prepared in this test and then placed in a beam fatigue fixture, which would allow four-point bending with free rotation and horizontal translation at loading. During each load cycle the beam deflections were measured at the center of the beam to calculate maximum tensile stress, maximum tensile strain, phase angle, stiffness and dissi-
Fig. 4 shows the indirect tensile modulus of asphalt mixture with two types of fillers at 5 °C, 25 °C and 40 °C, respectively. As shown in Fig. 4, the mixture with recycled brick filler has higher indirect tensile modulus at 5 °C and 40 °C than other mixtures, which is 1.27 times that of the control mixture at 5 °C. But its modulus at 25 °C is lower than that of the control mixture, which will result in better resistance against fatigue, because the fatigue cracking of asphalt pavement usually generates at the temperature of around 25 °C. Higher indirect tensile modulus of mixture with brick filler at 40 °C indicates that recycled brick fillers can increase the stiffness modulus of asphalt binder, which may improve the rutting resistance of asphalt mixture. 3.2. Water sensitivity Fig. 5 illustrates the indirect tensile strength of asphalt mixtures before and after freeze–thaw cycle at 25 °C. As shown in Fig. 5, the tensile strength of both mixtures decreases with the increase of freeze–thaw cycles, and the asphalt mixture with recycled brick filler has the higher indirect tensile strength than the control mixture. Fig. 6 illustrates the TSR value of two different asphalt mixtures after one cycle, two cycles and three cycles of freeze– thaw, respectively. As seen in Fig. 6, the asphalt mixture with recycled brick filler is always higher than the control mixture. It can be concluded that the mixture with recycled brick filler has better
Fig. 5. Indirect tensile strength of asphalt mixtures with different fillers.
1535
M.-z. Chen et al. / Construction and Building Materials 25 (2011) 1532–1536
Fig. 6. TSR value of asphalt mixtures with different fillers. Fig. 8. Dynamic creep strain of asphalt mixtures with different filler materials.
Fig. 7. Static creep strain of asphalt mixtures with different filler materials. Fig. 9. Cycle number to failure versus strain level of asphalt mixtures.
resistance against moisture damage while the mixture with limestone filler are more water sensitivity, which may be attribute to the fact that hydrophilic coefficient of recycled brick filler is lower than that of limestone filler (as seen in Table 2).
Table 4 Fatigue regression parameters of asphalt mixtures with different filler materials. Mixture types
3.3. High-temperature properties Asphalt mixture is a typical viscoelastic material especially at high temperature, and the viscoelastic property can reflect the deformation and rutting resistance of asphalt pavement. Road deformation can be dramatically reduced due to increasing the added filler content [12]. Therefore, the high-temperature performance can reflect the effect of filler on mixture. In this study, the static and dynamic creep tests at 60 °C were conducted to characterize the viscoelastic of asphalt mixture with two different fillers, and the results are shown in Figs. 7 and 8. As seen in Fig. 7, the asphalt mixture with brick powder has the lower permanent creep deformation than the mixture with limestone filler, which indicates that the asphalt mixture with recycled brick powder has better high-temperature performance with respect to control mixture. Fig. 8 shows the dynamic creep strain of asphalt mixtures. As seen in Fig. 8, the creep strain increases with the increase of load cycles. When the accumulative creep strain of both mixtures reaches 30,000 microstrain, the mixture with recycled brick filler has more load cycles, which is 2.1 times that of control mixtures. The results indicate that the mixture with recycled brick filler has better deformation resistance, which is consistent with the results of static creep test. This can be explained by the fact that recycled brick filler has higher porosity and adsorptivity than limestone filler, which results in better high-temperature performance of asphalt mastics and mixture. In addition, the density of recycled brick filler is lower than that of control filler, which results in much
Recycled brick filler Limestone filler
Fatigue regression parameters K
n
3.89 1017 3.71 1017
4.658 4.709
more recycled brick filler particle in asphalt mastics when the weight of filler is constant. As a result, the recycled brick filler has larger contacting area with asphalt binder than control filler, which also can improve the high-temperature stability of asphalt mixtures. 3.4. Fatigue life Previous researches [13,14] indicated that the fatigue behavior of asphalt concrete was closely related to the fracture characteristics of the asphalt matrix. In this study, the asphalt matrix is identical except filler type. Fig. 9 shows the number of cycles to failure in this test at 20 °C, and it can be seen in Fig. 9 that the sample with recycled brick filler exhibits higher fatigue life than the control mixture, which is 1.73 and 1.75 times that of control mixture at 500 and 600 microstrain respectively. It is obvious that using recycled brick filler can improve the fatigue performance of asphalt mixture. The fatigue performance of asphalt mixture can be depicted by the fatigue equation, as given in the following equation:
Nf ¼ KðeÞn
ð3Þ
1536
M.-z. Chen et al. / Construction and Building Materials 25 (2011) 1532–1536
where Nf is the cycle numbers to failure; e is the test strain, 106 mm/mm; K and n are the fatigue regression parameters. As shown in Table 4, the n value of asphalt mixture with recycled brick filler is 4.658, which is lower than that of control mixture, and the results indicate the asphalt mixture with recycled brick filler has longer fatigue life especially at high strain levels.
Acknowledgements Authors are thankful to the Project of Western Transportation Science and Technology from Ministry of Transportation of China (2009318811045) and International Science & Technology Cooperation Program of China (2010DFA82490). References
4. Conclusions This study focused on a laboratory evaluation of the mechanical performance of asphalt mixtures using recycled brick powders as filler. A comparison research was carried out for two different asphalt mixtures using recycled brick powder and limestone filler respectively. Based on the laboratory experiments and analyses, the following conclusions can be summarized and concluded: (1) The mixture with recycled brick filler had higher indirect tensile modulus at 40 °C, which indicated that the mixture with recycled brick filler exhibit better rutting resistance than the control mixture. (2) As compared with the limestone filler in this study, the addition of recycled brick filler could improve the water sensitivity and the fatigue life of asphalt mixtures. (3) The addition of recycled brick filler could also significantly decrease the permanent deformation at 60 °C by both static and dynamic creep tests, which result in better rutting resistance of asphalt mixture at high temperature. (4) Based on the above findings of the experimental results, it can be concluded that using the recycled brick powder as mineral filler in asphalt mixture is feasible, and further study on its field performance should be carried out to support findings from this study.
[1] Zhao W, Leeftinkb RB, Rotterc VS. Evaluation of the economic feasibility for the recycling of construction and demolition waste in China—The case of Chongqing. Resour Conserv Recy 2010;54(6):377–89. [2] Poon CX, Chan D. The use of recycled aggregate in concrete in Hong Kong. Resour Conserv Recy 2007;50(3):293–305. [3] Huang Y, Roger B, Oliver H. A review of the use of recycled solid waste materials in asphalt pavements. Resour Conserv Recy 2008;52(1):58–73. [4] Huang BS, Dong Q, Edwin G, Burdette. Laboratory evaluation of incorporating waste ceramic materials into Portland cement and asphaltic concrete. Construct Build Mater 2009;23(12):3451–5. [5] Debieb F, Kenai S. The use of coarse and fine crushed bricks as aggregate in concrete. Construct Build Mater 2009;22(5):886–93. [6] Tam VWY, Tam CM. A review on the viable technology for construction waste recycling. Resour Conserv Recy 2006;47(3):209–21. [7] Corinaldesi V, Giuggiolini M, Moriconi G. Use of rubble from building demolition in mortars. Waste Manage 2002;22(8):893–9. [8] Naceri A, Hamina MC. Use of waste brick as a partial replacement of cement in mortar. Waste Manage 2009;29(8):2378–84. [9] Ahmed HY, Othman AM. Effect of using waste cement dust as mineral filler on the mechanical properties of hot mix asphalt. Assoc Univ Bull Environ Res 2006;9(1):51–9. [10] Tapkin S. Mechanical evaluation of asphalt-aggregate mixtures prepared with fly ash as a filler replacement. Can J Civ Eng 2008;35(1):27–40. [11] Hwang SD, Park HM, Rhee Sk. A study on engineering characteristics of asphalt concrete using filler with recycled waste lime. Waste Manage 2008;28(1):191–9. [12] Dhir RK, Csetenyi LJ, Dyer TD, Smith GW. Cleaned oil-drill cuttings for use as filler in bituminous mixtures. Construct Build Mater 2010;24(3):322–5. [13] Kim Y, Little DN, Lytton RL. Fatigue and healing characterization of asphalt mixtures. J Mater Civ Eng 2003;15(1):75–83. [14] Song I, Little DN, Masad E, Lytton RL. Comprehensive evaluation of damage in asphalt mastics using X-ray CT, continuum mechanics, and micromechanics. J Assoc Asphalt Paving Technol 2005;74:885–920.
Contents lists available at ScienceDirect
Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat
Utilization of recycled brick powder as alternative filler in asphalt mixture Mei-zhu Chen a, Jun-tao Lin a, Shao-peng Wu a,⇑, Cong-hui Liu b a b
Key Laboratory of Silicate Materials Science and Engineering, Wuhan University of Technology, Ministry of Education, Wuhan 430070, PR China Shanxi Provincial Research Institute of Communication, Taiyuan 030000, PR China
a r t i c l e
i n f o
Article history: Received 4 May 2010 Received in revised form 26 July 2010 Accepted 23 August 2010 Available online 25 September 2010 Keywords: Asphalt mixture Filler Recycled brick powder Properties
a b s t r a c t The objective of this study is to investigate the use of recycled brick powder as replacement of mineral filler in asphalt mixture. A comparative study was carried out on the performance of two mixtures using recycled brick powder and limestone filler. The experimental performed were indirect tensile tests, static and dynamic creep tests, water sensitivity tests and fatigue tests. The results show that the mixtures prepared with recycled brick powder have better mechanical properties than the mixtures with limestone filler. Thus, it is promising to use recycled brick powder as mineral filler in asphalt mixture. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction About 90% highways in China are asphalt concrete pavements. The construction and maintenance of these pavements require large amounts of aggregates and mineral fillers, which typically account for nearly 95% of the asphalt concrete. The increase of civil infrastructures has led to a fast decrease of available natural resources, and seeking for other alternative is crucial. Recycling aggregates or fillers from the construction and demolition (C&D) waste is a preferable one. It is not only economically viable but also environmental friendly. At present, the total amount of C&D waste accumulated in China is estimated as 7000 million tons, and the annual amount of C&D waste due to building backout and construction is 200 million tons and 100 million tons respectively. Moreover, the amount of C&D waste is increasing in the rate of 10% every year. Brick is the largest component of C&D waste due to the traditional building habits and old-line production technology [1]. It is reported that around 20,000 million m3 clay bricks have produced in the past 50 years in China, most of which would be demolished in the later 50 years. Traditionally, waste bricks consumption is mainly disposed as soil conditioner or land filling. In recent years, reusing them as civil engineering materials has been brought into effect. Even if the combination of bricks constitutes a large portion of the C&D wastes, the using of waste brick aggregate is prohibited in Hong Kong [2]. A number of researches still have been done to ⇑ Corresponding author. Tel./fax: +86 27 87162595. E-mail addresses: [email protected] (M.-z. Chen), fl[email protected] (J.-t. Lin), [email protected] (S.-p. Wu), [email protected] (C.-h. Liu). 0950-0618/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.conbuildmat.2010.08.005
evaluate the potential use of crushed bricks as concrete aggregate, and some published reports indicates that the composition of crushed brick has considerable influence on the mechanical performance of concrete [3–5]. However, it seems that the use of bricks as concrete aggregate can not be widely applied. Waste bricks are applied as powder materials in some countries and areas. The demolished bricks are burned into slime burnt ash in Japan and are commonly crushed to form filling materials in Hong Kong [6]. In Italy, Corinaldesi et al. [7] evaluated the possibility of using brick powder as cementitious material replacing Portland cement, and they found out that the mortars containing bricks powder show good performance. Naceri and Hamina [8] also investigated the use of waste brick powder as a partial replacement for cement in the production of cement mortar, and confirmed the potential use of this waste material to produce pozzolanic cement. But until recently, there are few reports about using waste brick in asphalt mixture in the literatures. However, many researchers have been investigating other waste powders to replace the mineral filler in asphalt mixture. Ahmed and Othman [9] investigated the effect of using waste cement dust as mineral filler on the mechanical properties of asphalt mixture, and the results indicated cement dust can totally replace limestone powder in asphalt paving mixture. Tapkin [10] evaluated the effect of fly ash as a filler replacement on the mechanical properties of asphalt mixture and found that fly ash can be used effectively in a dense-graded wearing course as a filler replacement. Hwang et al. [11] investigated the potential use of waste lime as mineral filler in asphalt mixture, and the results suggested that using waste lime as mineral filler can improve the permanent deformation characteristics, stiffness and fatigue
1533
M.-z. Chen et al. / Construction and Building Materials 25 (2011) 1532–1536
endurance of asphalt mixture. Based on these researches above, the use of such waste powders as filler in asphalt mixture not only has no negative influence on asphalt mixture, but also can improve its engineering characteristics. Therefore, recycling waste bricks as filler for asphalt mixture may be an economic way in road and construction engineering, which can enlarge the application range and improve the utilization rate of C&D waste. This paper investigates the mechanical properties of asphalt mixtures using brick powder as mineral filler, and various tests including indirect tensile strength and modulus, static and dynamic creep and fatigue tests are conducted to evaluate the properties of asphalt mixtures. Based on these experimental results, the feasibility of waste brick powder as mineral filler in asphalt mixture is assessed comparing with control mixture using conventional limestone filler. 2. Materials and experiments 2.1. Materials
Table 3 Chemical composition of brick powder and limestone powder, %by mass. Component
Recycled brick power
Limestone powder
SiO2 CaO Al2O3 Fe2O3 MgO K2O Na2O TiO2 SO3 P2O5 MnO ZrO2 SrO ZnO BaO Cl LOI
68.10 2.05 16.35 6.04 1.43 2.38 1.20 0.85 0.11 0.26 0.06 0.05 0.02 0.03 0.07 0.00 0.80
17.95 46.90 0.46 0.52 3.64 0.10 0.08 0.03 0.02 0.04 0.14 0.11 0.02 0.01 0.02 0.00 29.95
Total
99.80
99.99
2.1.1. Asphalt binder One type of asphalt binder with normal paving grade 60/70 (AH70) was used to produce all test specimens in this study. This asphalt binder, which had a penetration of 65 (0.1 mm at 25 °C, 100 g and 5 s), ductility of 167.3 cm (at 15 °C) and softening point of 45.4 °C, was supplied by Koch Asphalt Co. Ltd., in Hubei Province, China. 2.1.2. Aggregate The basalt Aggregate used in this study was obtained from Jinmen, Hubei Province, China. And Table 1 gives the basic physical properties of basalt aggregate. In this study, four different sizes of crushed basalt aggregate were used, and they were 9.5–16, 4.75–9.5, 2.36–4.75 and 0–2.36 mm, respectively. 2.1.3. Filler Recycled bricks were obtained from the demolition building in Wuhan, China, which had nearly 20 years history. These clay bricks were washed with water, and then dried at 80 °C for 10 h. Finally, the recycled bricks were crushed by jaw crusher and ground by ball mill for 15 min to recycled brick powder. Limestone filler was used as the control sample. The basic properties of fillers were given in Table 2. The chemical and mineralogical compositions of fillers were given in Table 3 as measured by X-ray fluorescence (XRF). It can be seen in Table 3 that CaO, SiO2 and Al2O3 were typical constituents of these fillers, and limestone powder had considerable higher CaO content while brick powder had higher SiO2 content. The microscopic morphology of recycled brick powder and limestone powder were shown in Figs. 1 and 2 as measured by Scanning Electron Microscopy (SEM), respectively. It could be seen from these SEM results that the surface of recycled brick powder was much rougher and its particle distribution was more homogenous than that of limestone powder, which indicated the recycled brick powder has higher adsorption than limestone filler. Additionally, the draindown tests according to AASHTO T-305 and specific surface area tests were used to verify the high absorption of recycled brick powder. Draindown tests can reflect the content of free-asphalt in mixtures and the lower drainage value means the higher
Table 1 Basic properties of basalt aggregate in this test. Property
Measured values
Standard
Specific gravity (g/cm3) Water absorption ratio (%) Abrasion loss (%) Frost action (%)
2.719 0.82 13.6 0.64
ASTM ASTM ASTM ASTM
C-127 C-127 DC-131 C-88
Table 2 Basic properties of mineral filler in this test. Test items
Recycled brick powder
Limestone powder
Passing (%)
100.0 98.6 92.3 2.710 1.0 0.48
100.0 97.2 91.3 2.768 0.9 0.67
0.6 mm 0.3 mm 0.075 mm Specific gravity (g/cm3) Absorption (%) Hydrophilic coefficient
Fig. 1. SEM morphology of recycled brick powder.
absorption of powder in this test. Moreover, higher specific surface area also means higher absorption of powders. The tests results showed that the drainage value of the mixtures with recycled brick powder and limestone powder were 2.8 103 and 1.8 103, respectively, and the specific surface area of recycled brick powder and limestone powder were 446.8 cm2/g and 393.1 cm2/g, respectively. Therefore, the recycle brick powder has higher absorption than that of limestone powder. 2.1.4. Mixture deign and preparation In this study, aggregate grading curves for asphalt mixtures were obtained from China Highway Construction Specifications. Sieve analyses were carried out and available grading curve for the aggregate used in the study was shown in Fig. 3. Two types of fillers were used to produce mixture with the same aggregate and similar aggregate gradations. Marshall tests were carried out to find the optimum asphalt binder content of mixtures. The optimum asphalt binder content of asphalt mixture with recycled brick filler and limestone filler was 5.0% and 5.1% by weight of aggregate, respectively, and the mineral filler content of both asphalt mixtures was 4.0% by weight of aggregate. 2.2. Laboratory experiments 2.2.1. Indirect tensile modulus tests According to AASHTO TP31-standard test method for resilient modulus of asphalt mixture, the specimens with 63.5 mm in thickness and 101.6 mm in diameter were prepared and the resilient modulus of specimen was tested at the temperatures of 5 °C, 25 °C and 40 °C in order to understand insightfully the effect of temperature on the mixture. The test mode was under the assumed Poisson ration of 0.3, 0.35 and 0.4 for the different temperature 5 °C, 25 °C and 40 °C, respectively. 2.2.2. Water sensitivity tests AASHTO T-283 test was commonly used to evaluate the water sensitivity of asphalt mixtures. The specimen of 101.6 mm in diameter and 63.5 mm in height were prepared and then tested under the freeze–thaw cycles at the temperature between 18 °C and 60 °C. The indirect tensile strength of the conditioned and uncondi-
1534
M.-z. Chen et al. / Construction and Building Materials 25 (2011) 1532–1536
Fig. 2. SEM morphology of limestone powder. Fig. 4. Indirect tensile modulus of asphalt mixtures with different fillers.
pated energy. The failure of the flexural fatigue test could be defined as a 50% reduction in initial stiffness, which was measured from the center point of the beam after the 50th load cycle.
3. Results and discussion 3.1. Indirect tensile modulus
Fig. 3. Grading curves of aggregates.
tioned specimens was tested at 25 °C with the loading rate of 50 mm/min. Water sensitivity of mixture can be evaluated using the tensile strength ratio (TSR) value as follows:
TSR ¼ TS1 =TS2
ð1Þ
where TS1 is the average tensile strength of conditioned specimen, MPa; TS2 is the average tensile strength of unconditioned specimen, MPa.
2.2.3. Static and dynamic creep tests The static creep tests were carried out using Universal Testing Machine (UTM) to apply constant axial stress to asphalt specimens. The specimens of 100 mm in diameter and 100 mm in height were prepared and then tested at 60 °C. A stress of 100 KPa was applied on the specimens for 3600 s, then the load was removed and the deformation recovery was monitored for 5400 s. The accumulated microstrain was calculated as the ratio of the measured deformation to the initial specimen height according to the following equation:
e ¼ h=H0
ð2Þ
where e is the accumulated microstrain occurred in the specimen during a certain loading time at a certain temperature, 106 mm/mm; h is the axial deformation, mm; and H0 is the initial specimen height, mm. The dynamic creep tests were carried out using UTM to apply repeated axial stress pulse to asphalt specimens. The specimens of 100 mm in diameter and 100 mm in height were prepared and also tested at 60 °C. A haversine wave stress pulse was applied on the specimens for 10,000 s with frequency of 1 Hz (by allocating 100 ms for pulse width and 900 ms for rest period), and the test will be terminated when the accumulative stain reached 30,000 microstrain. The maximum axial stress was 100 KPa. During the test, the vertical deformation can be measured and the accumulated microstrain also can be calculated by the Eq. (2).
2.2.4. Fatigue tests The flexural beam test was conducted to evaluate the fatigue life of asphalt concrete at a temperature of 20 °C. According to AASHTO T-321, the beam specimens of 381 mm in length, 50.8 mm in thickness and 63.5 mm in width were prepared in this test and then placed in a beam fatigue fixture, which would allow four-point bending with free rotation and horizontal translation at loading. During each load cycle the beam deflections were measured at the center of the beam to calculate maximum tensile stress, maximum tensile strain, phase angle, stiffness and dissi-
Fig. 4 shows the indirect tensile modulus of asphalt mixture with two types of fillers at 5 °C, 25 °C and 40 °C, respectively. As shown in Fig. 4, the mixture with recycled brick filler has higher indirect tensile modulus at 5 °C and 40 °C than other mixtures, which is 1.27 times that of the control mixture at 5 °C. But its modulus at 25 °C is lower than that of the control mixture, which will result in better resistance against fatigue, because the fatigue cracking of asphalt pavement usually generates at the temperature of around 25 °C. Higher indirect tensile modulus of mixture with brick filler at 40 °C indicates that recycled brick fillers can increase the stiffness modulus of asphalt binder, which may improve the rutting resistance of asphalt mixture. 3.2. Water sensitivity Fig. 5 illustrates the indirect tensile strength of asphalt mixtures before and after freeze–thaw cycle at 25 °C. As shown in Fig. 5, the tensile strength of both mixtures decreases with the increase of freeze–thaw cycles, and the asphalt mixture with recycled brick filler has the higher indirect tensile strength than the control mixture. Fig. 6 illustrates the TSR value of two different asphalt mixtures after one cycle, two cycles and three cycles of freeze– thaw, respectively. As seen in Fig. 6, the asphalt mixture with recycled brick filler is always higher than the control mixture. It can be concluded that the mixture with recycled brick filler has better
Fig. 5. Indirect tensile strength of asphalt mixtures with different fillers.
1535
M.-z. Chen et al. / Construction and Building Materials 25 (2011) 1532–1536
Fig. 6. TSR value of asphalt mixtures with different fillers. Fig. 8. Dynamic creep strain of asphalt mixtures with different filler materials.
Fig. 7. Static creep strain of asphalt mixtures with different filler materials. Fig. 9. Cycle number to failure versus strain level of asphalt mixtures.
resistance against moisture damage while the mixture with limestone filler are more water sensitivity, which may be attribute to the fact that hydrophilic coefficient of recycled brick filler is lower than that of limestone filler (as seen in Table 2).
Table 4 Fatigue regression parameters of asphalt mixtures with different filler materials. Mixture types
3.3. High-temperature properties Asphalt mixture is a typical viscoelastic material especially at high temperature, and the viscoelastic property can reflect the deformation and rutting resistance of asphalt pavement. Road deformation can be dramatically reduced due to increasing the added filler content [12]. Therefore, the high-temperature performance can reflect the effect of filler on mixture. In this study, the static and dynamic creep tests at 60 °C were conducted to characterize the viscoelastic of asphalt mixture with two different fillers, and the results are shown in Figs. 7 and 8. As seen in Fig. 7, the asphalt mixture with brick powder has the lower permanent creep deformation than the mixture with limestone filler, which indicates that the asphalt mixture with recycled brick powder has better high-temperature performance with respect to control mixture. Fig. 8 shows the dynamic creep strain of asphalt mixtures. As seen in Fig. 8, the creep strain increases with the increase of load cycles. When the accumulative creep strain of both mixtures reaches 30,000 microstrain, the mixture with recycled brick filler has more load cycles, which is 2.1 times that of control mixtures. The results indicate that the mixture with recycled brick filler has better deformation resistance, which is consistent with the results of static creep test. This can be explained by the fact that recycled brick filler has higher porosity and adsorptivity than limestone filler, which results in better high-temperature performance of asphalt mastics and mixture. In addition, the density of recycled brick filler is lower than that of control filler, which results in much
Recycled brick filler Limestone filler
Fatigue regression parameters K
n
3.89 1017 3.71 1017
4.658 4.709
more recycled brick filler particle in asphalt mastics when the weight of filler is constant. As a result, the recycled brick filler has larger contacting area with asphalt binder than control filler, which also can improve the high-temperature stability of asphalt mixtures. 3.4. Fatigue life Previous researches [13,14] indicated that the fatigue behavior of asphalt concrete was closely related to the fracture characteristics of the asphalt matrix. In this study, the asphalt matrix is identical except filler type. Fig. 9 shows the number of cycles to failure in this test at 20 °C, and it can be seen in Fig. 9 that the sample with recycled brick filler exhibits higher fatigue life than the control mixture, which is 1.73 and 1.75 times that of control mixture at 500 and 600 microstrain respectively. It is obvious that using recycled brick filler can improve the fatigue performance of asphalt mixture. The fatigue performance of asphalt mixture can be depicted by the fatigue equation, as given in the following equation:
Nf ¼ KðeÞn
ð3Þ
1536
M.-z. Chen et al. / Construction and Building Materials 25 (2011) 1532–1536
where Nf is the cycle numbers to failure; e is the test strain, 106 mm/mm; K and n are the fatigue regression parameters. As shown in Table 4, the n value of asphalt mixture with recycled brick filler is 4.658, which is lower than that of control mixture, and the results indicate the asphalt mixture with recycled brick filler has longer fatigue life especially at high strain levels.
Acknowledgements Authors are thankful to the Project of Western Transportation Science and Technology from Ministry of Transportation of China (2009318811045) and International Science & Technology Cooperation Program of China (2010DFA82490). References
4. Conclusions This study focused on a laboratory evaluation of the mechanical performance of asphalt mixtures using recycled brick powders as filler. A comparison research was carried out for two different asphalt mixtures using recycled brick powder and limestone filler respectively. Based on the laboratory experiments and analyses, the following conclusions can be summarized and concluded: (1) The mixture with recycled brick filler had higher indirect tensile modulus at 40 °C, which indicated that the mixture with recycled brick filler exhibit better rutting resistance than the control mixture. (2) As compared with the limestone filler in this study, the addition of recycled brick filler could improve the water sensitivity and the fatigue life of asphalt mixtures. (3) The addition of recycled brick filler could also significantly decrease the permanent deformation at 60 °C by both static and dynamic creep tests, which result in better rutting resistance of asphalt mixture at high temperature. (4) Based on the above findings of the experimental results, it can be concluded that using the recycled brick powder as mineral filler in asphalt mixture is feasible, and further study on its field performance should be carried out to support findings from this study.
[1] Zhao W, Leeftinkb RB, Rotterc VS. Evaluation of the economic feasibility for the recycling of construction and demolition waste in China—The case of Chongqing. Resour Conserv Recy 2010;54(6):377–89. [2] Poon CX, Chan D. The use of recycled aggregate in concrete in Hong Kong. Resour Conserv Recy 2007;50(3):293–305. [3] Huang Y, Roger B, Oliver H. A review of the use of recycled solid waste materials in asphalt pavements. Resour Conserv Recy 2008;52(1):58–73. [4] Huang BS, Dong Q, Edwin G, Burdette. Laboratory evaluation of incorporating waste ceramic materials into Portland cement and asphaltic concrete. Construct Build Mater 2009;23(12):3451–5. [5] Debieb F, Kenai S. The use of coarse and fine crushed bricks as aggregate in concrete. Construct Build Mater 2009;22(5):886–93. [6] Tam VWY, Tam CM. A review on the viable technology for construction waste recycling. Resour Conserv Recy 2006;47(3):209–21. [7] Corinaldesi V, Giuggiolini M, Moriconi G. Use of rubble from building demolition in mortars. Waste Manage 2002;22(8):893–9. [8] Naceri A, Hamina MC. Use of waste brick as a partial replacement of cement in mortar. Waste Manage 2009;29(8):2378–84. [9] Ahmed HY, Othman AM. Effect of using waste cement dust as mineral filler on the mechanical properties of hot mix asphalt. Assoc Univ Bull Environ Res 2006;9(1):51–9. [10] Tapkin S. Mechanical evaluation of asphalt-aggregate mixtures prepared with fly ash as a filler replacement. Can J Civ Eng 2008;35(1):27–40. [11] Hwang SD, Park HM, Rhee Sk. A study on engineering characteristics of asphalt concrete using filler with recycled waste lime. Waste Manage 2008;28(1):191–9. [12] Dhir RK, Csetenyi LJ, Dyer TD, Smith GW. Cleaned oil-drill cuttings for use as filler in bituminous mixtures. Construct Build Mater 2010;24(3):322–5. [13] Kim Y, Little DN, Lytton RL. Fatigue and healing characterization of asphalt mixtures. J Mater Civ Eng 2003;15(1):75–83. [14] Song I, Little DN, Masad E, Lytton RL. Comprehensive evaluation of damage in asphalt mastics using X-ray CT, continuum mechanics, and micromechanics. J Assoc Asphalt Paving Technol 2005;74:885–920.