Crushed waste concrete in stone mastic asphalt mixtures/ Susmulkintojo betono lauzo panaudojimas skaldeles ir mastikos asfaltbetonio misiniams/Drupinats drupu betons skembu mastikas asfalta maisijumos/Purustatud vana betoon killustikmastiksasfalt segudes.

Kuo, Ming Feng ; Du, Jia Chong ; Shen, Der Hsien 等

1. Introduction

Due to 921 Chi-Chi Taiwan strong earthquake which caused many building damage and collapse in 1999, a large amount of waste concrete was demolished to the scrap heap and caused many environmental problems in this small island. In accordance with the statistical data report from the Ministry of the Interior, about 1 million cubic meters of waste concrete are produced every year in Taiwan. How to deal with the waste materials has become an environmental problem in a small island of Taiwan. The disposal of waste products primarily has three ways to deal with such as landfills, incineration and recycling. However, landfills are not suitable in Taiwan right now because of the large number of population living in such a small island so that there is no extra space for them. In addition, the waste building materials cannot be incinerated (Shen, Du 2004). Thus, one of the ways to reduce is crushed and recycled. The properties of the crushed waste concrete (CWC) have more impure materials, fracture and rough faces than general aggregates have (Shen, Du 2004, 2005).

Stone mastic asphalt (SMA) concrete composed of crushed coarse and fine aggregate, mineral filler, asphalt cement, and stabilizing agent is designed to have higher contents of coarse aggregate (70-80% by weight), asphalt (over 6% by weight) and filler (8-13% by weight) than normal hot mix asphalt has (Radziszewski 2007; Roberts et al. 1996; Sivilevicius 2002; Vislavicius 2002). Specially, the high coarse aggregate contents in stone on stone contact produce highly resistance to rutting (Radziszewski 2007; Shen, Du 2005; Sivilevicius, Petkevicius 2002). Interlocking makes the aggregates difficult to displacement by compaction. Sand particles within the aggregate gradation, contacts disappear between stone particles, so interlocking of stone particles is weak (Haryanto, Takahashi 2007). The crushed waste concrete (CWC) used as aggregate in stone mastic asphalt (SMA) mixture can also provide more shear strength resistance than general asphalt mixtures do; and the probability of shear strains in asphalt concrete is higher when the pavement temperature is high (Laurinavicius, Cygas 2003). Thus, SMA with CWC increasing the stress resistance of asphalt concrete could solve the problem. In addition, the mixture is new and its engineering properties and performance need to be evaluated. Thus, in order to reduce waste concrete, an investigation of the CWC recycled as an aggregate and replaced all or part of the virgin aggregate for SMA mixtures was carried out.

Asphalt pavement in actual circumstances is subjected to the repetitive and changing transport load. As a result of the repetitive load impact, both elastic and plastic deformations occur to the pavement. Accumulation of plastic deformations in one or several layers leads to appearance of permanent deformations or rutting. This type of deformations reduces safety and convenience of traffic (Haritonovs et al. 2010). The binder of modified asphalt was used for the Marshall mix design; and permanent deformation and resilient modulus test were carried out.

2. Plan of study

The performance of laboratory compacted SMA mixtures were as follows:

--100% virgin crush stone (CS) (100% CS);

--100% CWC;

--50% coarse and fine CWC plus 50% coarse and fine CS (50% CWC plus 50% CS);

--coarse CWC plus fine CS (C-CWC plus F-CS);

--coarse CS plus fine CWC(C-CS plus F-CWC), mixed with modified asphalt cement.

Permanent deformation and resilient modulus test were used for determining the laboratory performance of the CWC mixtures. Based on the laboratory tests, the ANOVA analysis was used to evaluate the significant effects and to determine the best mix proportions based on laboratory performance.

3. Laboratory evaluation

3.1. Aggregate, binder and gradation

The CWC used as aggregate was obtained from Sindian City, Taiwan. CS was obtained from local quarry field. The hydrated lime as a mineral filler was from a commercial source. The properties of CWC and CS aggregate are shown in Table 1. Processed CWC aggregate has higher angular, rougher surface texture, lower specific gravity, higher Los Angeles abrasion, higher sodium soundness, and higher water absorption than the CS.

Polymer modified asphalt cement shown in Table 2 was from local petroleum company. The aggregate gradation used throughout the study shown in Table 3 was developed in accordance with ASTM D3515-01 Standard Specification for Hot-Mixed, Hot-Laid Bituminous Paving Mixtures (ASTM D3515). Lime used as filler is applied instead of the aggregates passing No. 200 sieve (0.075 mm).

3.2. Mix design

SMA mix design was performed following the Marshall method in accordance with ASTM D1559 Test Method for Resistance of Plastic Flow of Bituminous Mixtures Using Marshall Apparatus. 18 batching samples of SMA mixed with varied asphalt contents in 0.5% increment were heated and compacted. All of the samples were compacted by 50 blows per face with the standard Marshall compactor. The Marshall stability and flow were determined by the standard Marshall equipment (Haryanto, Takahashi 2007). The optimum asphalt content (OAC) was determined at 4% air void contents in accordance with the National Asphalt Pavement Association 1982 Mix Design Techniques--Part I. Instructors Manual.

3.3. Permanent deformation test

Ruts are treated as dangerous defects, since they might cause danger for traffic, especially when the pavement is wet (Laurinavicius, Oginskas 2006). The permanent deformation test was performed employing the wheel-tracking device following the wheel tracking device testing procedure (Nienelt, Thamfald 1988). The facility was developed by the Swiss and modified by the University of Hokkaido, Japan. The samples, mixed with optimum asphalt contents from Marshall mix design and fabricated by the rolling machine were 300 x 300 mm in section area and 50 mm in height. The test was performed using 2.18 MPa wheel load at test temperatures of 25 [+ or -] 10[degrees]C and 60 [+ or -] 1[degrees]C for dry condition. The depth of deformation was measured at 100, 200, 400, 800, 1400, 1890 and 2520 cycles.

3.4. Resilient modulus test

The resilient modulus ([M.sub.R]) test, following ASTM D4123 Standard Test Method for Indirect Tension Test for Resilient Modulus of Bituminous Mixtures, is the most common method of measuring stiffness modulus for hot mixture asphalt. All tests were conducted on triplicate samples at test temperatures of 40 [+ or -] 1[degrees]C and 25 [+ or -] 1[degrees]C. The resilient modulus test was performed after 50 pulse cycles and determined by the following equation:

[M.sub.R] = P(v + 0.27)/[[delta].sub.h]h,

where [M.sub.R]--resilient modulus, MPa; P--applied load, kN; v--Poisson's ratio; [[delta].sub.h]--horizontal deformation, cm; h--sample thickness, cm.

4. Results and discussion

The tests described above were conducted, and the data described in the following sections were collected on all samples.

4.1. Marshall design properties

The properties of the SMA mixture specimens are shown in Table 4. In Table 4 all of the stability values of CWC mixtures satisfied with the specification requirements is greater than 6.24 kN and higher than that of 100% CS mixture. Compared to conventional CS mixtures in terms of the stability and flow values of all types of replacement, the max value of stability and min flow occur in the 100% CWC and C-CS plus F-CWC mixture, respectively. All of the voids in mineral aggregate (VMA) greater than 17% are satisfied with the criteria. However, 100% CWC and C-CWC plus F-CS are not satisfied with flow criteria of the Marshall mix design. As shown in Table 1, the bulk specific gravity of CWC is less than that of CS. This is primary reason that unit weights of all SMA with CWC are less than CS. In addition, CWC aggregate has more angular and rougher surface texture than CS has. Thus, SMA with CWC has higher OAC and higher stability due to increase resistance by aggregate's stone on stone contact (interlocking).

4.2. Permanent deformation

The results of the average deformation of each sample from the tests at 25 and 60[degrees]C are plotted in Figs 1 and 2, respectively. All of the deformations are less than 1.00 mm at 25[degrees]C and 2.50 mm at 60[degrees]C, and the CS has the lowest deformation at test temperature of 25[degrees]C, but the highest deformation at test temperature of 60[degrees]C. In Fig. 2, the 100% CWC and 50% CWC plus 50% CS have the lowest deformation. The deformation at 60[degrees]C indicates that it appears to be plastic flow not densification. Due to the internal friction between aggregate particles providing the ability of deformation resistance, plastic flow can be minimized by using large size aggregate, angular and rough textured coarse and fine aggregates (Roberts et al. 1996). Therefore, the smaller observed deformation of the 50% CWC plus 50% CS suggests that these mixes have more angular and rougher particles than that of CS mixture, and thus have higher internal friction.

In general, it is believed that the higher asphalt contents provide higher plastic flow susceptibility. The high plastic susceptibility may lead to high permanent deformation, due to too much asphalt cement in the mix causing loss of internal friction between aggregate particles, which results in the loads being carried by the asphalt cement rather than the aggregate structure. In Table 4, although the CWC mixtures have higher asphalt contents than the CS mixtures, this is not the case for deformation following the preceding description. The phenomenon may be explained by the fact that the high proportion of internal friction plays the main role in deformation resistance. To determine the statistical significance of the effect of aggregate type on the wheel load deformation test, a one-way analysis of variance (ANOVA) was performed on the test. The ANOVA was performed to determine whether the treatments were significant at a confidence limit of 95%. Table 5 shows the results of the ANOVA test and indicates that the type of aggregate has a significant effect at temperature of 60[degrees]C, but not a significant effect at temperature of 25[degrees]C. This situation suggests that the angular and rough textured aggregate play the main role in the deformation resistance of SMA at high temperature.

4.3. Resilient modulus

The [M.sub.R] test results are shown in Fig. 3. As can be seen in Fig. 3, the CS aggregate mixture has the highest [M.sub.R] values at test temperatures of 25[degrees]C and 40[degrees]C. The 50% CWC + 50% CS and 100% CWC mixtures have a 2nd high [M.sub.R] values at test temperature of 25[degrees]C and 40[degrees]C, respectively. The high modulus values should provide cost effectiveness and min practical thickness. In addition, [M.sub.R] values above 3100 MPa (450 000 psi) at 20[degrees]C are stiffer and more resistant to bending according AASHTO1993 Guide for Design of Pavement Structures. However, high values of [M.sub.R] at low temperatures are somewhat related to cracking (Roberts et al. 1996). Fortunately, low temperature cracking never happens in Taiwan due to the high and mild temperatures present the whole year. Thus, the high [M.sub.R] values of the CWC mixtures provide a good capacity for distress resistance.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

5. Conclusions

The data analysis indicates that the performance of SMA with CWC in Taiwan is related to the highly crushed face and high absorption of asphalt cement aggregate. The aggregate contributed to the internal friction for deformation resistance. Based on the results of this study, the following conclusions and recommendations are suggested to improve the performance of SMA with CWC:

--the stability values of the CWC mixtures are higher than the 100% CS mixture, especially in 50% CWC + 50% CS and C-CS + F-CWC;

--the ANOVA of the permanent deformation test shows that the type of aggregate has a significant effect at temperature of 60[degrees]C but not at temperature of 25[degrees]C. Thus, the ability of permanent deformation resistance of the CWC mixture is better than that of 100% CS mixture;

--the SMA mixed with 50% CWC + 50% CS are more practicable for use than others;

--the CWC used as aggregate in SMA mixture can provide better performance than general asphalt mixtures do, and find a way to solve the environment problem related to the large amount of waste concrete.

[FIGURE 3 OMITTED]

6. Acknowledge

This study was supported by National Science Council of Taiwan (NSC 89-2211-E011-071).

doi: 10.3846/bjrbe.2010.23

Received 19 September 2008; accepted 10 May 2010

References

Haritonovs, V.; Smirnovs, J.; Naudzuns, J. 2010. Prediction of Rutting Formation in Asphalt Concrete Pavement, The Baltic Journal of Road and Bridge Engineering 5(1): 38-42. doi:10.3846/bjrbe.2010.05

Haryanto, I.; Takahashi, O. 2007. Effect of Aggregate Gradation on Workability of Hot Mix Asphalt Mixtures, The Baltic Journal of Road and Bridge Engineering 2(1): 21-28.

Laurinavicius, A.; Oginskas, R. 2006. Experimental Research on the Development of Rutting in Asphalt Concrete Pavements Reinforced with Geosynthetic Materials, Journal of Civil Engineering and Management 12(4): 311-317.

Laurinavicius, A.; Cygas, D. 2003. Thermal Conditions of Road Pavements and Their Influence on Motor Traffic, Transport 18(1): 23-31.

Nienelt, G.; Thamfald, H. 1988. Evaluation of the Resistance to Deformation of Different Road Structures and Asphalt Mixtures Determined the Pavement Rutting Tester, Journal of Association of Asphalt Paving Technologists (57): 320-345.

Radziszewski, P. 2007. Modified Asphalt Mixtures Resistance to Permanent Deformations, Journal of Civil Engineering and Management 13(4): 307-315.

Roberts, F. L.; Kandhal, P. S.; Brown, E. R.; Lee, D. Y.; Kennedy, T. W. 1996. Hot Mix Asphalt Materials, Mixture Design and Construction. 2nd edition. NAPA research and education foundation, Maryland. 575 p. ISBN: 0914313010.

Shen, D. H.; Du, J. C. 2005. Application of Gray Relational Analysis to Evaluate HMA with Reclaimed Building Materials, Journal of Material in Civil Engineering 17(4): 400-406. doi:10.1061/(ASCE)0899-1561(2005)17:4(400)

Shen, D. H.; Du, J. C. 2004. Evaluation of Building Materials Recycling on HMA Permanent Deformation, Construction and Building Materials 18(6): 391-397. doi:10.1016/j.conbuildmat.2004.03.007

Sivilevicius, H. 2002. Theoretical Principles and Experimental Data to Identify Stability of Asphalt Concrete Components in Finally Dosed Mineral Materials, Transport 17(1): 19-29.

Sivilevicius, H.; Petkevicius, K. 2002. Regularities of Defect Development in the Asphalt Concrete Road Pavements, Journal of Civil Engineering and Management 8(3): 206-213.

Vislavicius, K. 2002. Determination of Optimum Quantity of Bitumen in Asphalt Concrete Mixtures, Journal of Civil Engineering and Management 8(1): 73-76.

Ming Feng Kuo (1), Jia Chong Du (2), Der Hsien Shen (3)

(1) Dept of Safety Health and Environmental Engineering, Institute of Safety and Disaster Prevention Technology, Central Taiwan University of Science and Technology, No. 666, Buzih Road, Beitun District, Taichung, 406, Taiwan

E-mail: mfkuo@ctust.edu.tw

(2) Dept of Construction Technology, Tung Nan University, No. 152, Sec. 3, PeiShen Rd., ShenKeng, Taipei, 222, Taiwan

E-mail: cctu@mail.tnu.edu.tw

(3) Dept of Construction Engineering, National Taiwan University of Science and Technology, No.43, Sec.4, Keelung Rd., Taipei, 106, Taiwan

E-mail: shendh@mail.ntust.edu.tw

Table 1. The properties of CWC and CS

Property                           Specification      CS      CWC

Bulk specific gravity, coarse            --         2.655    2.273
Bulk specific gravity, fine              --         2.516    2.261
Absorption, %                            --         0.600     6.1
Unit weight, kg/[cm.sup.3]               --          2012     1503
Los Angeles abrasion, %                 < 40        20.20     40.7
Sodium soundness (5 cycles), %          < 12        9.220     52.2
Elongated, %                           > 0.67       0.690     0.71
Flat, %                                > 0.67       0.680     0.69
Rounded index                            --         0.520     0.61
Shape factor, %                          --          0.53     0.57

Table 2. The properties of modified asphalt cement

Property                            Specification    Testing

Penetration, 1/100 cm                    > 50          55.2
Specific gravity, 25[degrees]C            --          1.028
Softening point, [degrees]C               --           50.5
Ductility, kgf-cm, 25[degrees]C           --           97.9
Viscosity, 60[degrees]C, poise          > 4500         7255
Viscosity, 135[degrees]C, cst           < 3000         2365
Penetration, 25[degrees]C, 100 g,        > 50          55.2
  5 s, 1/100 cm
Penetration, 40[degrees]C, 200 g,        > 10          23.1
  60 s, 1/100 cm

Table 3. Aggregate gradation

                        SMA
Sieves                12.5 mm              SMA               Testing

19 mm                   100                100                 100
12.5 mm                90-100             85-95               92.5
9.5 mm                 40-60               < 75                50
No. 4                  20-35              20-28                24
No. 8                  15-25              16-24                20
No. 30                   --               12-16                14
No. 50                   --               12-15               13.5
No. 200                 7-12               8-10                 9
Asphalt content, %    6.5-7.5             > 6.0              6.5-7.5
Fibre content, %                   Cellulose fibre 0.3%
Void, %                                    2-4
VMA, %                                     > 17
Blows                                  50 each side

Table 4. SMA mixture properties at optimum asphalt contents

                             OAC, %

                        by
                    aggregate    by total    Unit weight,   Void,
Aggregate             weight      weight     kg/[m.sup.3]      %

Specification           --          --            --          2-4
CS                     6.10        5.75          2332          4
100% CWC               7.65        7.11          2058          4
50% CWC + 50% CS       6.50        6.10          2195          4
C-CWC + F-CS           7.18        6.70          2069          4
C-CS + F-CWC           6.93        6.48          2298          4

                     VMA,     VFA,    Stability,     Flow,
Aggregate             %        %          kN        0.01 cm

Specification        > 17      --       > 6.24       20-40
CS                  17.00     76.3       6.45         38.0
100% CWC            17.40     77.0       9.95         43.9
50% CWC + 50% CS    17.40     76.0       8.15         33.8
C-CWC + F-CS        17.33     77.0       8.29         52.0
C-CS + F-CWC        18.00     78.0       6.84         32.5

Table 5. One way ANOVA test on permanent deformation

Source of
variation        SS      df      MS       F      [F.sub.0.05]

               Temperature at 25[degrees]C

Types of        0.596     4    0.149    2.494       2.670
  aggregate
Within          1.792    30    0.060
Total           2.388    34

               Temperature at 60[degrees]C

Types of        3.221     4    0.805    3.547       2.690
  aggregate
Within          6.809    30    0.227
Total          10.030    34