Mechanical performance evaluation of taconite aggregate in asphalt pavement construction

Augusto Cannone Falchetto; Ki Hoon Moon; Sang Gab Cho

doi:10.22702/jkai.2022.12.1.15

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Scientific Paper

Journal of the Korean Asphalt Institute. 18 July 2022. 155-164
https://doi.org/10.22702/jkai.2022.12.1.15

Mechanical performance evaluation of taconite aggregate in asphalt pavement construction

Augusto Cannone Falchetto¹

Ki Hoon Moon²^*

Sang Gab Cho³⁴

¹Assistant Professor, Department of Civil Engineering, Aalto University

²Principal Researcher, Korea Expressway Corporation R&D Planning Division

³Ph.D. Candidate, Department of civil engineering, Seoul national University of Science And Technology

⁴Pro, Green Solution Business Development Team 1, SK Ecoplant

^{*Corresponding Author}

ABSTRACT

Using alternative aggregate source is essential in asphalt pavement industry not only for saving construction budget but also for mitigating environmental pollution issue. In U.S. northern Minnesota territory, amount of taconite aggregate: a byproduct of taconite mining industries, are produced annually. If taconite aggregate is successfully used as an alternative aggregate source, more economical and environment friendly asphalt mixture can be achieved. Many studies presented the possibility of taconite aggregate application in road construction. In this paper, suitability investigation of using taconite aggregate is performed by means of mechanical test: low temperature Indirect Tensile (IDT) creep test. A parameter for low temperature cracking resistance: creep stiffness (and corresponding relaxation modulus) result, is computed then compared visually. It was found that the asphalt mixture mixed with coarse taconite aggregate and limestone filler presented reasonable mechanical performance compared to the conventional asphalt mixture. This finding provides possibility of taconite aggregate application in actual asphalt pavement construction.

Keywords

Taconite aggregate

Indirect Tensile (IDT) test

Creep compliance

Relaxation modulus

Mechanical performance

MAIN

1. Introduction
2. Material preparation for experimental work
3. Experimental work
4. Mechanical performance factor computation process part [1] : creep stiffness
5. Mechanical performance factor computation process part [2] : relaxation modulus
6. Data analysis
7. Summary and conclusion

1. Introduction

Asphalt mixture is a composite material consisted of three major components: aggregate, asphalt binder and air void, in volumetric concept (Moon, 2012; Cannone Falchetto et al., 2021). Asphalt mixture holds the mechanical performance through the physical connection between aggregate and asphalt binder. Moreover, the load bearing capacity is heavily rely on the characteristics of aggregate interlock system (Moon, 2010; Moon 2012; Cannone Falchetto et al., 2021). Therefore, it can be said that selecting proper aggregate source directly affects the performance of asphalt pavement. The asphalt pavement construction budget (i.e. not only for new-construction but also for repair work) in U.S. increased approximately 7 to 8 percent annually (PWMS, 2021). This business trend makes development and application of alternative (and/or recyclable) aggregate source in asphalt pavement not only inevitable but also essential (Oreskovich and Patelke, 2006; Moon et al., 2014). Using alternative aggregate source is essential in asphalt pavement industry not only for saving construction budget but also for mitigating environmental pollution issue. Application of alternative aggregates such as Reclaimed Asphalt Pavement (RAP), roofing shingles and taconite were considered in many pavement agencies during the past decades (Moon et al., 2014; Cannone Falchetto et al., 2021). In U.S. northern Minnesota territory, amount of taconite aggregate: a byproduct of taconite mining industries, are produced annually. Taconite ore: sort of iron ore, is consisted of five major elements: quartz, magnetite, various amount of iron oxides (e.g. hematite), carbonate and silicates (Zanko et al., 2003). In taconite aggregate the dominant mineral is quartz takes 55~60% portion approximately followed by 8~12% of hematite and 10% of magnetite (Zanko et al., 2003). The previous studies presented high compressive strength (e.g. 193~621 MPa) of iron formation rock (taconite) compared to the conventional compressive strength of limestone (e.g. 55~179 MPa) (Plummer, 1976; Stump and Hetzer, 1999). The specific gravity value of taconite is ranged 2.9 to 3.1 which is approximately 10% higher than the conventional aggregate. Moreover, absorption is 1.2% which is slightly higher than conventional granite aggregate: 0.74% (Zanko et al., 2003). The major chemical composition of taconite aggregate is presented in Table 1. Many studies presented the possibility of taconite aggregate application in road construction through various basic experimental evaluation process (Oreskovich and Patelke, 2006). However, mechanical performance of taconite material as an alternative aggregate source was not studied extensively. In this paper, suitability investigation of using taconite aggregate is performed by means of mechanical test: low temperature Indirect Tensile (IDT) creep test (AASHTO, 2003). A parameter for low temperature cracking resistance: creep stiffness: S(t) (and corresponding relaxation modulus: E(t)) result, is computed then compared visually.

Table 1.

Chemical composition of taconite aggregate

Component	Percentage (%)
SiO₂ : Silicon dioxide	66.18%
Fe₂O₃ : Iron (III) oxide	22.84%
LOI : Loss on ignition	5.56%
MgO : Magnesium oxide	2.82%
CaO : Calcium oxide	1.40%
MnO : Manganese (II) oxide	0.62%
Al₂O₃ : Aluminium oxide	0.39%
Others	0.19%
Sum	100.00%

2. Material preparation for experimental work

One of remarkable achievement of taconite aggregate is this material has been used mixtures in asphalt pavement. Even though taconite aggregate has been applied in many pavement projects in U.S., there are not many publishing work related to mechanical performance of mixtures with these materials. In this paper, taconite aggregate was provided by United Taconite American Corporation (UTAC) Thunderbird mine in Eleventh located in northern Minnesota (e.g. Cuyuna range, Mesabl range and Vermillion range). Table 2 shows the schematic information of asphalt mixtures prepared in this paper. All the asphalt mixtures were designed based on Minnesota Department of Transportation (MN/DOT) specification (Zanko, 2009). More detailed information about the asphalt mixture design is mentioned elsewhere (Zanko, 2009). All the asphalt mixtures were made cylindrical shaped testing specimen by means of Super-pave Gyratory Compactor (SGC) in University of Minnesota pavement research center. Then the cylindrical shaped specimen was cut into specified dimension (i.e. diameter: 150 mm thickness: 40 mm) to perform low temperature Indirect Tensile (IDT) creep test (AASHTO, 2003). Prepared asphalt mixture sample picture for IDT testing (AASHTO, 2003) is shown in Fig. 1.

Table 2.

Prepared asphalt mixtures in this research

Mixture ID	Asphalt mixture information
Mixture [1] Control Limestone 100% [L]	- Type : Control mixture (100% Limestone) - Mixture : Regular Hot Mix Asphalt (HMA) mixture Designed for regular county roadway network - Asphalt binder content : 4.5~5.2% (PG 64-28) - Air-void : 3.9~4.5% - Aggregate gradation (sieve passing percentage) : 20.0 mm : 100%, 10.0 mm : 95%, 5.0 mm : 75%, 2.5 mm: 48%, 0.60 mm : 25%, 0.30 mm : 13%, 0.08 mm : 5%
Mixture [2] Comparison Taconite + Taconite Filler [T+TF]	- Type : Comparison mixture (Taconite + Taconite Filler) Asphalt mixture was prepared with 100% taconite aggregate - Mixture : Regular Hot Mix Asphalt (HMA) mixture Designed for regular county roadway network - Asphalt binder content : 4.3~5.0% (PG 64-28) - Air-void : 4.0~4.3% - Aggregate gradation (sieve passing percentage) : 20.0 mm : 100%, 10.0 mm : 93%, 5.0 mm : 68%, 2.5 mm: 41%, 0.60 mm : 21%, 0.30 mm : 11%, 0.08 mm : 3%
Mixture [3] Comparison Taconite + Limestone Filler [T+LF]	- Type : Comparison mixture (Taconite + Limestone Filler) Asphalt mixture was prepared with coarse taconite aggregate and limestone filler - Mixture : Regular Hot Mix Asphalt (HMA) mixture Designed for regular county roadway network - Asphalt binder content : 4.5~5.1% (PG 64-28) - Air-void : 3.9~4.4% - Aggregate gradation (sieve passing percentage) : 20.0 mm : 100%, 10.0 mm : 97%, 5.0 mm : 65%, 2.5 mm: 46%, 0.60 mm : 23%, 0.30 mm : 12%, 0.08 mm : 4%

https://static.apub.kr/journalsite/sites/jkai/2022-012-01/N0850120115/images/jkai_12_01_15_F1.jpg

Fig. 1.

Prepared asphalt mixture sample for IDT testing

3. Experimental work

It is well known that low temperature cracking takes a crucial factor in asphalt pavement when alternative (and/or recyclable) aggregate resource is considered rather than using conventional aggregate (Moon, 2010; Moon et al., 2014). Due to this reason, a widely known low temperature cracking resistance performance evaluation testing method: IDT test (AASHTO, 2003), was considered. Fig. 2 and Table 3 present IDT testing set up picture and testing information, respectively.

https://static.apub.kr/journalsite/sites/jkai/2022-012-01/N0850120115/images/jkai_12_01_15_F2.jpg

Fig. 2.

IDT creep testing set up (AASHTO, 2003)

Table 3.

Schematic information of IDT creep testing

Mixture ID	IDT test information
Mixture [1] Mixture [2] Mixture [3]	- Testing temperature: -24°C - Number of specimens : 3 - Applied load amount : 7.0~8.5 kN for 1,000 seconds - Computation results : deflections Horizontal (x, mm) and vertical (y, mm) deflections

4. Mechanical performance factor computation process part [1] : creep stiffness

The creep stiffness: S(t), is widely known as low temperature mechanical parameter for bituminous material such as asphalt mixture (Moon et al., 2014). In viscoelastic theory, creep stiffness: S(t) can be easily computed from the results of creep compliance: D(t), as can be seen Equation (1).

(1)

S (t) = \frac{1}{D (t)}

In IDT test, creep compliance: D(t), can be computed as (Zhang et al., 1997):

(2)

D (t) = \frac{1}{S (t)} = \frac{{H^{(t)}}_{m} \cdot D \cdot T}{P \cdot G L} \cdot C_{c}

(3)

C_{c} = 0.6354 \times {(\frac{x}{y})}^{- 1} - 0.332

(4)

\frac{x}{y} = \frac{ε_{x} (at 500 seconds)}{ε_{y} (at 500 seconds)}

Where,

D(t) = creep compliance (1/MPa),

S(t) = creep stiffness (MPa),

H^(t)_m = measured horizontal deflection at time t (mm),

D = diameter of test specimen (=150 mm),

T = thickness of test specimen (=40 mm),

GL = gauge length (=38 mm),

P = applied load (7.0~8.5 kN, constantly),

Creep stiffness: S(t), can be computed from Equations (1) to (4).

5. Mechanical performance factor computation process part [2] : relaxation modulus

In this paper, not only creep stiffness: S(t), but also relaxation modulus: E(t), was computed then compared to provide feasibility of taconite aggregate application extensively. In case of viscoelastic material, E(t) and D(t) can be expressed based on experimental works as:

(5)

\{\begin{cases} E (t) = E_{1} \cdot \frac{1}{t^{n}} \\ D (t) = D_{1} \cdot t^{n} \end{cases}

In Equation (5), E₁ and D₁ are positive constants (Park and Kim, 1999).

By applying Laplace transformation, Equation (5) can be expressed as:

(6)

\{\begin{cases} L [E (t) = E_{1} \cdot \frac{1}{t^{n}}] = \bar{E} (s) = E_{1} \cdot \frac{Γ (1 - n)}{s^{1 - n}} \\ L [D (t) = D_{1} \cdot t^{n}] = \bar{D} (s) = D_{1} \cdot \frac{Γ (1 - n)}{s^{1 + n}} \end{cases}

(7)

Γ (n) = \int_{0}^{\infty} t^{n - 1} \cdot e^{- t} d t

Based on inter-conversion theory, E(t) and D(t) can be inter-related as (Park and Kim, 1999; Moon, 2010):

(8)

E (t) \cdot D (t) ≅ 1

(9)

\{\begin{array}{l} \int_{0}^{t} E (t - τ) \cdot D (t) d τ = \int_{0}^{t} E (t - τ) \cdot \frac{1}{S (t)} d τ = t \\ \int_{0}^{t} E (t) \cdot D (t - τ) d τ = \int_{0}^{t} E (t) \cdot \frac{1}{S (t - τ)} d τ = t \end{array} \Rightarrow \{\begin{cases} L [\int_{0}^{t} E (t - τ) \cdot D (t) d τ] = L (t) = \bar{E} (s) \cdot \bar{D} (s) = \frac{1}{s^{2}} \\ L [\int_{0}^{t} E (t) \cdot D (t - τ) d τ] = L (t) = \bar{E} (s) \cdot \bar{D} (s) = \frac{1}{s^{2}} \end{cases}

Finally, E(t) can be expresses from Equations (5) to (9) :

(10)

\bar{D} (s) = \frac{1}{E_{1} \cdot Γ (1 - n)} \cdot \frac{1}{s^{n + 1}}

(11)

D (t) = L^{- 1} [\bar{D} (s)] = \frac{1}{E_{1} \cdot Γ (1 - n)} \cdot \frac{t^{n}}{Γ (1 + n)}

(12)

D (t) = \frac{1}{E (t)} \cdot \frac{\sin (n \cdot π)}{n \cdot π} \Rightarrow E (t) = \frac{1}{D (t)} \cdot \frac{\sin (n \cdot π)}{n \cdot π} = S (t) \cdot \frac{\sin (n \cdot π)}{n \cdot π}

(13)

n = {|\frac{\partial Log D (t)}{Log τ}|}_{τ = t} o r n = {|\frac{\partial Log E (t)}{Log τ}|}_{τ = t}

In this paper, results of S(t) and E(t) from asphalt mixtures mentioned in Table 2 were computed then compared visually.

6. Data analysis

The computed results of S(t) and E(t) are presented in Figs. 3 to 4 and Tables 4 to 5. It is found that taconite aggregate added mixture (i.e. Mixture [2] and [3]) presented relatively high amount of S(t) and E(t) compared to the conventional asphalt mixture (i.e. Mixture [1]). When asphalt mixture is consisted of 100% taconite aggregate (i.e. Mixture [2]), relatively high amount of S(t) and E(t) was computed which is negative on low temperature cracking resistance. However, when asphalt mixture is consisted of coarse taconite and fine lime stone filler (i.e. Mixture [3]), almost identical S(t) and E(t) computation values and trends were observed compared to the conventional asphalt mixture (i.e. Mixture [1]).

https://static.apub.kr/journalsite/sites/jkai/2022-012-01/N0850120115/images/jkai_12_01_15_F3.jpg

Fig. 3.

Computation results of S(t) : Mixture [1], [2], [3] (temp -24°C)

https://static.apub.kr/journalsite/sites/jkai/2022-012-01/N0850120115/images/jkai_12_01_15_F4.jpg

Fig. 4.

Computation results of E(t) : Mixture [1], [2], [3] (temp -24°C)

Table 4.

Data comparison result: S(t), for Mixture [1], [2], [3]

Time [sec]	Creep stiffness : S(t) [GPa]
Time [sec]	Mixture [1]	Mixture [2]	Mixture [3]	[1]-[2]	[1]-[3]
1	26.239	23.336	19.987	2.904	6.252
2	24.003	21.890	18.512	2.113	5.491
3	23.085	20.786	18.267	2.298	4.818
4	21.554	19.948	17.568	1.605	3.985
5	20.408	20.613	17.347	-0.205	3.061
8	18.859	19.948	16.225	-1.089	2.634
11	17.243	17.178	15.761	0.065	1.481
16	16.063	15.856	15.239	0.206	0.824
22	14.668	16.601	14.750	-1.933	-0.082
31	13.243	16.601	13.521	-3.358	-0.278
44	11.934	15.557	12.369	-3.623	-0.435
60	11.001	15.755	11.493	-4.754	-0.491
89	9.536	14.637	10.448	-5.100	-0.912
120	8.604	12.008	10.369	-3.404	-1.765
178	7.681	11.613	10.030	-3.932	-2.349
240	7.296	10.802	9.611	-3.505	-2.314
355	6.803	10.138	8.566	-3.335	-1.763
500	6.420	10.393	8.042	-3.973	-1.621
708	6.185	9.816	7.903	-3.631	-1.718
1,000	6.096	9.625	7.516	-3.529	-1.420

Table 5.

Data comparison result: E(t), for Mixture [1], [2], [3]

Time [sec]	Relaxation modulus : E(t) [GPa]
Time [sec]	Mixture [1]	Mixture [2]	Mixture [3]	[1]-[2]	[1]-[3]
1	23.774	22.598	19.227	1.176	4.548
2	21.748	21.198	17.807	0.550	3.941
3	20.916	20.129	17.571	0.787	3.345
4	19.529	19.318	16.900	0.211	2.629
5	18.491	19.961	16.687	-1.470	1.804
8	17.088	19.318	15.607	-2.230	1.480
11	15.623	16.635	15.162	-1.011	0.462
16	14.554	15.355	14.659	-0.801	-0.105
22	13.290	16.076	14.189	-2.786	-0.898
31	11.999	16.076	13.006	-4.077	-1.007
44	10.813	15.065	11.898	-4.253	-1.086
60	9.968	15.257	11.055	-5.289	-1.087
89	8.640	14.174	10.050	-5.534	-1.410
120	7.796	11.628	9.975	-3.832	-2.179
178	6.959	11.246	9.648	-4.287	-2.689
240	6.611	10.460	9.245	-3.849	-2.634
355	6.164	9.817	8.240	-3.653	-2.076
500	5.817	10.065	7.735	-4.247	-1.918
708	5.604	9.505	7.602	-3.901	-1.998
1,000	5.523	9.321	7.230	-3.797	-1.706

As a result, positive possibilities of taconite aggregate application on asphalt mixture production could be found. More extensive experimental works (e.g. number and types of testing material, conditions etc.) along with various mechanical performance computation approach (e.g. inter-conversion analysis, thermal stress computation etc.) are recommended as a future research topic to verify findings in this paper.

7. Summary and conclusion

In this paper, feasibility of taconite aggregate application on actual asphalt pavement was considered. Two different taconite aggregate added asphalt mixtures were prepared and tested. The low temperature cracking resistance ability was evaluated by means of mechanical testing: IDT mixture creep test. Relatively negative performance was found when asphalt mixture is consisted of taconite aggregate only. However, reasonable performance was observed when asphalt mixture is consisted of coarse taconite aggregate and fine limestone filler compared to the conventional asphalt mixture. This provides a positive possibility of taconite aggregate application in actual asphalt pavement construction. More extensive research efforts are needed to further verify findings in this study. In addition, environmental effect of taconite application on actual asphalt pavement construction needs to be crucially studied.

References

AASHTO (2003). Determining the creep compliance and strength of Hot Mix Asphalt using the Indirect Tensile Test (IDT) device, AASHTO T322-03, American Association of State Highway and Transportation Officials, Washington D.C.

Cannone Falchetto, A., Moon, K.H., Wang, D. and Park H.W. (2021). “A modified rheological model for the dynamic modulus of asphalt mixtures”, Canadian Journal of Civil Engineering, 48, pp. 328-340. 10.1139/cjce-2019-0392

Moon, K.H. (2010). Comparison of thermal stresses calculated from asphalt binder and asphalt mixture creep compliance data, M.S. thesis, University of Minnesota Twin Cities, United States (U.S.).

Moon, K.H. (2012). Investigation of asphalt binder and asphalt mixture low temperature properties using analogical models. Ph.D. thesis. University of Minnesota Twin Cities, United States (U.S.).

Moon, K.H., Cannone Falchetto, A., Marasteanu, O.M. and Turos, M. (2014). “Using recycled asphalt materials as an alternative material source in asphalt pavements”, Korea Society of Civil Engineering, 18(1), pp. 149-159. 10.1007/s12205-014-0211-1

Oreskovich, J.A. and Patelke, M.M. (2006). Historical use of taconite byproducts as construction aggregate materials in Minnesota: a progress report, Report of investigation NRRI/RI-2006/02, Natural Resources Research Institute, University of Minnesota, Duluth, MN; 2006. 10p.

Park, S.W. and Kim, Y.R. (1999). “Interconversion between relaxation modulus and creep compliance for viscoelastic solids”, American Society of Civil Engineers: Journal of Materials in Civil Engineering, 11(1), pp. 76-82. 10.1061/(ASCE)0899-1561(1999)11:1(76)

Public Works Maintenance Surface Team (2021). An update on asphalt pavement conditions and programs (2021 rating and inventory data), 2021 Pavement management report, Accredited agency (APWA), United States (U.S.).

Plummer, W.L. (1976). Physical properties of some Mesabi range magnetic taconites-data from Mesabi deep drilling project, Progress report no. 1, Data sheet no. 5, IRRRC State of Minnesota, United States (U.S.).

Stump, B.W. and Hetzer, C. (1999). Ground truth with mine cooperation-Minnesota taconite mines, Southern Methodist University, Department of Geological Sciences, Seismicity and Industrial Mining, p. 13.

Zanko, L.M., Niles, H.B. and Oreskovich, J.A. (2003). Properties and aggregate potential of coarse taconite tailings from five Minnesota taconite operations, Technical report NRRI/TR-2003/44; and local road research board report number 2004-06, Natural Resources Research Institute, University of Minnesota Duluth, United States (U.S.), 227p.

Zanko, L.M. (2009). Gray is green: the aggregate potential of Minnesota taconite industry byproducts, In: Transportation Research Board (TRB) 2009 annual meeting CD-ROM, Washington D.C. 10.1061/41072(359)27

Zhang, W., Drescher A. and Newcomb, D.E. (1997). “Viscoelastic behavior of asphalt concrete in diametral compression”, Journal of Transportation Engineering, 123(6), pp. 495-502. 10.1061/(ASCE)0733-947X(1997)123:6(495)

Journal of the Korean Asphalt Institute ISSN:2234-0785(Print) 2635-9553(Online) 한국아스팔트학회지

Preview

Mechanical performance evaluation of taconite aggregate in asphalt pavement construction

ABSTRACT

MAIN

Table 1.

Chemical composition of taconite aggregate

Table 2.

Prepared asphalt mixtures in this research

Fig. 1.

Prepared asphalt mixture sample for IDT testing

Fig. 2.

IDT creep testing set up (AASHTO, 2003)

Table 3.

Schematic information of IDT creep testing

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

Fig. 3.

Computation results of S(t) : Mixture [1], [2], [3] (temp -24°C)

Fig. 4.

Computation results of E(t) : Mixture [1], [2], [3] (temp -24°C)

Table 4.

Data comparison result: S(t), for Mixture [1], [2], [3]

Table 5.

Data comparison result: E(t), for Mixture [1], [2], [3]

References