1

PERFORMANCE EVALUATION OF ASPHALT CONCRETE MIXES

CONTAINING GRANULAR VOLCANIC ASH

Naji, Jamil A1. and Asi, Ibrahim M.2

ABSTRACT

Granular volcanic ash material is spread over considerable areas of Yemen including urban

and suburban areas. Due to the inferior properties of this material in its natural state, it can

not be used in base and sub-base layers. It is common practice, when faced with such

material, to replace it with superior properties filling material. Excavated volcanic ash is

disposed off by transporting it to landfill sites. Such practice is becoming increasingly costly

and continuously necessitates allocation of scares and valuable new landfill sites. The

problem in some urban areas is becoming an environmental issue due to the massive build up

of disposed volcanic ash material.

The main objectives of this study are twofold. One to investigate the merits of utilizing waste

volcanic ash as a cheap alternative to aggregate for road construction and consequently this

contributes towards an efficient waste management of this undesirable material and reduce its

environmental impact.

The effects of using granular volcanic ash material, as a partial replacement of conventional

aggregate, on the properties of Hot-Mix Asphalt (HMA) were studied. Four different

aggregate replacement proportions were used specifically at 0, 10, 20 and 30% of total weight

of dry aggregate. The 0% volcanic ash content mix was used as the reference mix.

Experimental results indicated that for all the mixes containing volcanic ash aggregate, the

properties were within the specification limits of Marshall mix design method. In addition, it

was found that the use of volcanic ash aggregate improved the HMA creep resistance

1 [Corresponding Author] Associate professor, Civil Engineering Department, Sana'a University, P.O. Box

14166, Sana'a, Yemen. Jamil.abdulrabb@gmail.com

2 Associate professor, Civil Engineering Department, Hashemite University, P.O. Box 150459, Zarqa 13115,

Jordon. asi@hu.edu.jo.

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properties. HMA with a 10% volcanic ash aggregate replacement gave optimum results in

terms of stripping resistance, creep resistance, fatigue and resilient modulus.

Keywords

volcanic ash, asphalt pavements, stability, tensile strength, creep, fatigue life, resilience.

INTRODUCTION

Road construction in Yemen has grown at a substantial rate following the re-unification of

the North and South of the country in 1990. A significant portion of the Country’s Gross

National Product (GNP) goes to road construction. The average government investment on

rural road building, compared to total annual investment plan, has risen from 12.5% in 1997

to more than 23% in 2005. Clearly a major portion of the state investment goes to roads

construction. The country has almost completed the construction of about 8000km of two

ways two lanes paved rural roads. Major portion of these roads are arterials connecting the

main cities in the country.

The use of the good quality conventional crushed aggregate materials in road

construction is becoming increasingly expensive in Yemen due to the increasing demand of

these materials and the scarcity of the good quality materials. Attempts should be made to

explore the utilization of other sources of materials in the most effective and economical

manner.

Many parts of Yemen, particularly in Sana'a region, are covered with natural granular

volcanic ash. Many sites of granular volcanic ash are located in urban and suburban areas.

Owing to its low density, cohesion-less nature, relatively high percentage of voids, and other

undesirable properties, volcanic ash in its natural state cannot be used in road base and sub-

base layers. Therefore, it is considered as a waste/undesirable material. When faced volcanic

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ash in construction sites, it is common practice to dispose it and replace it with superior

filling material. The excavated waste ash is transported to landfill sites. Such solution is

expensive, and the amount of hauled materials is increasing with time which consequently

necessitates the continuous allocation of new landfill sites. Due to the massive amount of

such materials, the problem in some urban areas is becoming an environmental issue.

Clearly, a better waste management system of such materials is needed. One possible way to

resolving this problem is to recycle this waste material by improving its physical properties

and utilizing it in the construction industry.

The gradation of volcanic ash varies depending on its source location, but in general

the maximum aggregate size of the material ranges between 12 and 18 mm. Since the

volcanic ash contains very little or no fine material, it is cohesion-less in nature. So far this

material has not been practically used in engineering applications. However, if properly

designed, the material can be considered as one of the alternative sources that can be used in

road construction.

Available literature indicates that the use of volcanic ash in road construction is very

limited and therefore, this study can be considered as a pioneer study in this field in Yemen.

Available studies indicated that some sort of stabilization procedure for volcanic ash can be

implemented so that this material can be used as base and subbase layers in the flexible

pavement structures (Naji 2002 and Naji & Ali 2000).

A number of researches were performed to study the effect of using volcanic

aggregate in concrete mixes, especially for producing light weight concrete and light weight

masonry units (Demirdag et al. 2007, Demirdag and Gunduz 2006, Hossain 2006, Alonso et

al. 2001).

In order to improve the performance of HMA to meet the requirements under

prevailing conditions, different researchers have used fillers and special types of aggregates

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in their studies for that purpose. In a recent study, Asi and Shalabi (2007) investigated the

possibility of improving the properties of asphalt concrete mixes by replacing different

portions of the limestone aggregate by basalt. The replacement included total replacement of

the limestone by basalt, replacing the coarse aggregate only, and replacing the fine aggregate

only. Results showed that the optimal mix was the mix that had basalt coarse aggregate and

limestone fine aggregate. Other researchers (Richardson 1914; Tunnicliff 1962; Anani and

Al-Abdul Wahhab 1982; Kandhal et al. 1998, Asi and Assa'ad 2005) used different types of

fillers, material passing sieve #200, in their studies. These include dust from the crushing and

screening of aggregates, lime, Portland cement, fly ash and oil shale ash. Although fillers

usually contribute small portion, 5% to 7%, of the total aggregate mix, they have great effect

on the HMA properties. Usually, filers are used to improve bonding between asphalt cement

and aggregate, lower the optimum asphalt content (OAC), increase the density, and increase

the stability (Brown et al. 1989).

In this paper, the possibility of using volcanic ash material as a partial replacement of

conventional aggregate in HMA was investigated and results are presented. Since changes in

mix composition usually influences mix properties, work was oriented to find out how the

inclusion of volcanic ash will affect properties of HMA. Therefore, different levels of

granular volcanic ash were used in the study and optimum volcanic ash content was obtained.

RESEARCH OBJECTIVES

The scope of this research is limited to the following:

o To study the main characteristics of the available granular volcanic ash and to

review available literature on the subject of using granular volcanic ash in road

construction

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o To study the effect of utilizing granular volcanic ash, as a partial substitute of the

aggregates, on the behavior of HMA.

o To investigate the merits of utilizing waste volcanic ash as a cheap alternative of

aggregate for road construction and consequently to contribute towards an efficient

waste management of this undesirable material and reduce its environmental impact.

MATERIALS AND EXPERIMENTAL PROGRAM

A flowchart describing the different levels of the followed experimental program is shown in

Figure 1. The experimental work included one asphalt cement grade, "60/70 pen" AC, one

crushed basalt stone aggregate source, and one granular volcanic ash source. Details of the

experimental program are given in the next paragraphs.

Materials characteristics

Asphalt

In this study, "60/70 pen" AC was used as the binder as it is widely used in Yemen.

Penetration (ASTM D-5), ductility (ASTM D-113), and specific gravity (ASTM D70-82)

tests were performed on the binder and the obtained properties test results are shown in Table

1. The performance grade of the used AC is PG 64-16.

Aggregate and filler

Two types of aggregates were used in this study; basalt aggregate, which is the most available

and frequently used type of aggregate in road construction in Yemen, and granular volcanic

ash aggregate. The volcanic ash was used as a partial replacement of the basalt aggregate.

Four different mixes with varying proportions of volcanic ash were examined. The

proportions of volcanic ash as a percentage of total aggregate dry weight were 0%, 10%, 20%

and 30%. Two different sizes of volcanic ash particles were used. The first size was that

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passing through sieve No 4 (4.75 mm) and retained on sieve No. 10 (2.0 mm) and the second

size was that passing through sieve No. 16 (1.18 mm) and retained on No 50 (0.3 mm).

These two types were found to form the bulk quantity of volcanic ash in their natural state

and are readily available. Therefore, the use of these types is expected to be the most

economical. The gradation of the aggregate used in this study is shown in Table 2 and the

aggregate nominal maximum size (NMAS) is 19.0 mm.

a) Basalt aggregate

Abrasion loss (ASTM C535-96), impact value (BS 812), specific gravity & absorption

(AASHTO T85) tests were conducted on the basalt material and the results are shown in

Table 3.

b) Granular volcanic ash

The granular volcanic ash was subjected to a series of tests to determine its basic properties.

This included, gradation test (ASTM D421-58), specific gravity (AASHTO T85), resistance

to abrasion (ASTM C535-96) and some other index properties. Also a sample of the grinded

material was subjected to Atterberg limits determination in accordance with AASHTO T89

and T90. The classification of the volcanic ash was found to be well graded gravel (GW) and

(A1-a) in accordance with Unified Soil Classification System (USCS) & AASHTO

classification, respectively. A summery of the volcanic ash index properties and chemical

composition is shown in Tables 4 and 5, respectively.

c) Mineral filler

Dust, material passing sieve # 200, obtained from the crushing and screening of basalt

aggregates was used as mineral filler. The main reason for using this filler is its abundance

availability and its wide use locally. The physical properties of the filler are included in Table

3.

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Experimental work

Mix design

Although Marshall mix design is being phased out in favor of SuperPave even in some

developing countries, this research have utilized Marshall procedure (ASTM D1559) due to

lack of relevant testing facilities in Yemen (namely, Superpave Gyratory Compactor).

Four mix designs, with different granular volcanic ash composition of 0%, 10%, 20% and

30% of total aggregate weight were used in this study. The 0% ash content mix design was

used as a reference mix. Seventy-five blows on each side of the 4 inch specimens were

applied in accordance with Marshall requirement for heavy traffic. The mixing and

compaction temperatures were 160±2° C and 145±2° C, respectively.

Five AC percentages were used in each mix design. Three samples (replicates) were

prepared at each AC percentage. Prepared samples were subjected to bulk specific gravity,

and stability-flow tests. Then the density-voids analysis was performed and obtained results

were graphically analyzed.

For each level of volcanic ash content, OAC that produced 4% air void was obtained

and used to determine the corresponding Marshall Stability, Flow, Voids filled with asphalt

(VFA) and Voids in Mineral Aggregate (VMA). These values were checked to verify that

they were within the specification limits given in the Asphalt Institute Manual Series MS-2

(1997).

Evaluation criteria

The four mixes, at their optimal asphalt contents, were evaluated using a number of different

tests to predict field performance namely Marshall Stability, Flow, VFA, and VMA. Al-Kadi

(2002) stated that evaluation criteria using conventional evaluation procedures are not

sufficient to provide critical evaluation of paving mixtures. Therefore, the use of more

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advanced paving mix tests is necessary to evaluate important mix characteristics. This

includes water sensitivity, fatigue life, creep resistance and dynamic modulus. Thus, the

results from these tests were used as additional evaluation criteria.

For each level of ash content and at its OAC, enough samples were prepared to study

the pervious mentioned properties.

RESULTS AND DISCUSSION

The following paragraphs present the effect of the volcanic ash inclusion on the different

properties of the HMA.

a) Effect of volcanic ash content on the optimum asphalt content (OAC)

The effect of volcanic ash on the OAC needed for the mixture was studied. Results

are presented in Figure 2. It is `clear from the figure that the OAC increases with increasing

volcanic ash content. This can be attributed to the fact that granular volcanic ash contains

some vesicles (voids) which were created by the expanding of the gas bubbles during the

eruption of magma (USGS 2000). These vesicles tend to store part of the asphalt resulting in

more required asphalt.

Statistical analysis using Statistical Package for Social Science (SPSS) software was

performed to study whether or not there are statistically significant differences between the

OAC means, i.e. to check if the difference in the obtained OAC values is due to experimental

error or due to the inclusion of the volcanic ash. One way Analysis of Variance (ANOVA)

for the single factor model was used for this analysis. The appropriate procedure for testing

the differences of treatment means (µ's) is to check the following hypothesis, (Montgomery

1991):

H0 : µ1 = µ2 = ………. = µn (1)

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H1 : at least two means are not equal (2)

For testing the previous hypothesis, ANOVA utilizes F test in which the estimate of

between-groups variance (SSR) is compared with the estimate of within-groups variance

(SSE) i.e., F = SSR/SSE. If the SSR is considerably larger than SSE, then the value of the F

ratio will be higher, which indicates that the differences between the means are unlikely to be

due to chance, (Bryman and Cramer 1990).

The F ratio considered high if its significance level (S.L.) is less than the selected

S.L., which is usually selected to be 5%. Thus, the S.L. should be less than 0.05 in order to

achieve significant effect of any factor.

Results from ANOVA, Table 6, indicate that OAC means are significantly different

from each other and this differnce is due to the different percentages of volcanic ash.

b) Effect of volcanic ash content on stability and flow

As expected, the inclusion of the granular volcanic ash has influenced the behavior of the

asphalt mixes. Figure 3 shows the relationship between Marshal Stability and volcanic ash

content. The general trend shows that as the ash content increases the stability slightly

decreases. This might be attributed to the porous nature of volcanic ash which led to lower

strength compared with basalt aggregate.

Although the stability slightly decreased with increasing the ash content, the stability

of mixes at volcanic ash contents up to 20% were within the limits of Marshall criteria for

heavy traffic, i.e., above 8 KN (1800 Lb). Statistical analysis using one way ANOVA was

used to check whether or not the differences between stability means, of the studied volcanic

ash contents, are statistically different. Results form ANOVA revealed that stability means

are significantly different at 5% S.L.

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The flow property of the mixture, as shown in Figure 4, increases slightly with the

increase in the amount of volcanic ash, and this may be due to the increased amount of the

asphalt content with the increase of the ash content. Although the flow increased with the

increase of the ash content, the flow at all levels of volcanic ash contents was also within the

limits of Marshall Criteria for heavy traffic, i.e. 2 to 3.5mm.

c) Effect of volcanic ash content on unit weight

Figure 5 illustrates the effect of granular volcanic ash content on sample unit weight. The

densities of the HMA samples containing granular volcanic ash were lower than those made

without the addition of volcanic ash and this is ascribed to the lower specific gravity of the

volcanic ash compared with that of basalt aggregates.

d) Effect of volcanic ash content on VMA and VFA

Studying VMA is important because it represents the space that is available to accommodate

the effective volume of asphalt and the volume of air voids necessary in the mixture.

Therefore, minimum VMA is necessary to achieve an adequate asphalt film thickness, which

results in a durable asphalt pavement. Increasing density of aggregate gradation to a point

where below minimum VMA values are obtained leads to thin films of asphalt and low

durability mix. Thus, economizing in asphalt content by lowering VMA is actually counter-

productive and detrimental to pavement quality (Asphalt Institute 2001).

In this study, effect of volcanic ash addition on VMA percentage was evaluated and

results are shown in Figure 6. It can be seen that VMA increases with increase in the

percentage of granular volcanic ash content. This effect might be attributed to the presence of

vesicles in volcanic ash particles. These vesicles tend to increase the VMA in the mixture. All

obtained values of VMA were within the limits of Marshall criteria given in Asphalt Institute

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Manual series MS-2 (1997) for the used gradation, i.e. 19 mm nominal maximum particle

size gradation.

Figure 7 shows the relationship between the volcanic ash content and the percentage

of VFA. As indicated by the graph, the VFA decreases with increase in the ash content. The

reason for such decrease may be attributed to the increase in VMA with volcanic ash content

at a higher rate than that of OAC.

It is important to indicate that all obtained values were within the specification limits

given in the Asphalt Institute Manual Series MS-2 (1997).

Statistical analysis using one way ANOVA indicates that VFA means are

significantly different at 5% S.L.

e) Water sensitivity test (Lottman test, AASHTO T-283-89)

The resistance to stripping (water susceptibility) of the asphalt concrete mixes containing

granular volcanic ash was evaluated by measuring the loss of the indirect tensile strength

(ITS) after immersion in water for 24 hrs at 60°C, in accordance with AASHTO T-283 test

procedure. To obtain samples having air voids close to 7% and since no Gyratory Compactor

was available, samples were compacted by applying forty-five blows on each sample side

using the Marshall compactor. The obtained results, Figure 8, indicate that the average loss in

strength due to water damage was increased by the increase in the quantity of the granular

volcanic ash. Factors that might have influenced this trend are the relatively high

permeability of volcanic ash particles and the low unit weight of samples containing granular

volcanic ash compared to control samples.

The loss in ITS value at 10% volcanic ash content was within the allowable limit, i.e.,

20% loss in ITS (Cominsky et al. 1994). At percentages higher than 10% volcanic ash

content, the loss in ITS was higher than the allowable limit. Therefore, it is necessary either

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to improve the stripping resistance of the mixes containing more than 10% granular volcanic

ash by adding antistripping agent, like lime or cement, or by limiting the granular volcanic

ash content to 10%.

f) Dynamic creep

The Dynamic Creep Test is a test that applies a repeated pulsed uniaxial stress/load to an

asphalt specimen and measures the resulting deformations in the same axis using Linear

Variable Displacement Transformers (LVDTs). Repeated uniaxial load strain test was

performed in accordance with the protocol developed by US, NCHRP 9-19 Superpave

Models Draft Test Method W2 -Unconfined (Witczak et al. 2001). The applied stress on the

specimens was haversine in shape. The loading pulse repetition of 1000 milliseconds (ms) (1

sec.) and pulse width of 100 ms (0.1 sec.) was selected. The deviator stress during each

loading pulse was 69 kPa, and the constant stress that was used to prevent lifting off the test

specimen during the rest period was 11 kPa. The test was performed at 25°C. The

specimen’s skin and core temperatures during the test were monitored by two thermocouples

which were inserted in a dummy specimen and located near the specimen under test. The test

was continued until the maximum axial strain limit reached 10000 micro-strains, or until

10000 cycles, whichever occurred first.

Four inch specimens, compacted using the Marshall compactor at the OAC for each

mix, were used in this test. Figure 9 shows typical relationship between number of load

repetitions and the percentage of accumulated strain for the tested samples at the different

volcanic ash contents (i.e. 0%, 10%, 20%, & 30%). The figure indicates that as the volcanic

ash content increases the accumulated strain decreases. This suggests that volcanic ash affects

the creep properties of the mixture in a positive manner and this might be attributed to the

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rough texture properties of volcanic ash particles which resulted in an improvement of the

interlocking properties of the aggregate in the mix (Asi & Shalabi 2007).

In addition, creep stiffness analysis indicated that creep stiffness increased with the

increase of the volcanic ash content. As indicated in Equation 3, creep stiffness is the ratio

between the deviator stress and the axial accumulated/permanent strain. Creep stiffness gives

indication about resistance of the HMA to creep.

Eca = σd / ∈pa (3)

where,

Eca is the axial creep stiffness (MPa)

σd is the deviator stress (kPa)

∈pa is the axial accumulated/permanent strain (micro-strain or %).

One way ANOVA for the single factor model was used for the analysis of the creep

stiffness means. Results indicate that at 5% S.L., creep stiffness means are significantly

different form each other and this differnce is due to the variation of the volcanic ash

percentage.

g) Fatigue resistance

Fatigue is considered one of the significant distress modes in pavements that are associated

with repeated traffic loads. The fatigue resistance of an asphalt concrete mix is its ability to

withstand repeated loading without fracture. Fatigue in asphalt concrete pavements starts at

the bottom of the asphalt concrete layer and propagates to the surface of the pavement.

In this research, fatigue tests were conducted using universal hydraulic testing

equipment and a haversine loading pulse having a 0.25 sec loading time and 1.25 sec rest

time. Tests were performed at 25ºC in an environmental chamber where the temperature of

the specimens was maintained within ±1ºC of the set temperature. Controlled-stress repeated

indirect tensile loading was used in the fatigue study. For comparison reasons, the applied

repeated loading was varied to create nearly the same initial tensile strain for all the test

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samples. Six 4"x2.5" Marshall compacted cylindrical samples for each volcanic ash content

were tested. Loading was continued until complete failure (splitting) of the test sample.

Fatigue life, which is the number of load repetitions until failure was recorded for each

sample.

Figure 10 shows the effect of volcanic ash content on fatigue life. The figure indicates

that fatigue life was improved at 10% addition of volcanic ash. However, considerable

decrease in fatigue life was noticed at higher volcanic ash contents. The reason behind the

increase in fatigue life at 10% volcanic ash content may be due to the rough surface texture of

the granular volcanic ash particles which resulted in an improvement in the interlocking of

the aggregate. When the percentage of the granular volcanic ash increased, the lower strength

of the granular volcanic ash was more effective than its rough texture. A previous study,

conducted on basalt and lime aggregate, reported close results (Asi & Shalabi 2007).

h) Resilient modulus test (MR).

Resilient Modulus of HMA is conducted by applying pulsed compressive loads with a

haversine waveform. The load is applied vertically in the vertical diametral plane of the

cylindrical specimen of the asphalt concrete mix. The resulting total recoverable diametral

deformation (Horizontal) is then measured from an axes 90° from the applied force. A

resilient Poisson’s ratio is calculated by dividing the measured recoverable vertical

deformation by the horizontal deformation. The total resilient modulus is calculated using the

total recoverable deformation which includes both the instantaneous recoverable and the

time-dependent continuing recoverable deformation during the unloading and rest-period

portion of one cycle (ASTM D-4123). The test would usually be used to gauge the relative

performance of HMA for road pavement design and to evaluate the relative quality of

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materials (ASTM 2003). Resilient Modulus value varies with temperature and speed/time of

loading due to the AC visco-elastic behavior (Kamal et al. 2005).

In this study, 4" X 2.5" cylindrical samples were prepared at OAC for resilient

modulus testing. Eight replicates for each mix were tested under the diametral resilient

modulus (MR) test. The test was performed by applying a pulse width of 0.1 sec and a pulse

repetition of 1.0 sec at 25°C test temperature.

Effect of volcanic ash content on resilient modulus values are presented in Figure 11.

The figure indicates that replacement of part of aggregate by granular volcanic ash (up to 20%

ash content) has increased the diametral resilient modulus. However, MR value decreased at

higher ash contents. The rough surface texture of the granular volcanic ash particles which

resulted in an improvement of the interlocking of the aggregate was the reason behind the

increase in the MR values at the low volcanic ash contents. At higher volcanic ash contents,

the effect of the lower strength of the granular volcanic ash was more effective than its rough

texture, resulting in the decrease of the MR values.

Statistical analysis was performed to study the significance of replacing aggregate by

volcanic ash in changing the MR values. ANOVA analysis indicated that there is significant

difference in the means of the MR values at different volcanic ash contents. This indicates

that the differences in MR values are due to treatments rather than experimental errors.

CONCLUSIONS AND RECOMMENDATIONS

In this research, the effects of using granular volcanic ash material, as a partial replacement

of conventional basalt aggregate, on the properties of HMA were studied. Four different

aggregate replacement proportions were used specifically at 0, 10, 20 and 30% of total weight

of dry aggregate. Effectiveness of the replacement was judged mainly by the improvements

in stripping resistance, resilient modulus, fatigue life, and creep resistance of the tested

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samples. The following can be concluded regarding the use of granular volcanic ash in

HMA:

o Experimental results proved that partial replacement of basalt aggregates by granular

volcanic ash is technically feasible.

o The use of volcanic ash in road construction will serve two purposes. One to reduce the

construction cost, and two the contribution towards an efficient waste management of this

undesirable material.

o Except for stability at 30% volcanic ash content, the used volcanic ash percentages didn't

move the volumetric properties of the HMA outside Marshall mix design specification

limits.

o Obtained loss of indirect tensile strength results indicated that using up to 10% granular

volcanic ash will generate mixes that have appropriate stripping resistance.

o Mixes containing volcanic ash aggregate are expected to perform well in terms of creep

resistance.

o The use of up to 10% volcanic ash aggregate in asphalt concrete mixes will improve both

the resilient modulus and fatigue life.

o The asphalt concrete mix that has basalt aggregate, 10% volcanic ash aggregate, and

basalt dust mineral filler was found to be the optimal mix, i.e., it has the best mechanical

properties among all the included mixes.

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17

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on Use of Basalt in AC Mixes, Great Amman Municipality, Jordan.

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Ed.

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Demirdag, S., Ugur, I. and Sarac, S. (2007). "The Effects of Cement/Fly Ash Ratios on the

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Building Materials, In Press, Corrected Proof, Available online 12 July 2007.

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Demirdag, S. and Gunduz, L. (2006). "Strength Properties of Volcanic Slag Aggregate

Lightweight Concrete for High Performance Masonry Units." Construction and Building

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Engineering Uses." Proc., The 8th

Arab Conference for Structural Engineering, Cairo

University, Oct. 21-23 2000, 3, 1099-1111.

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Table 1: Basic properties of the used asphalt cement

Property Value

Penetration 60/70

Specific gravity 1.03

Ductility cm 150.00

Table 2: Used aggregate gradation in the study

Specification Limits

(% Pass)

Sieve Size

(mm)

Lower Upper

Used Gradation

(% Pass)

25.000 100 100 100.0

19.000 90 100 95.0

12.500 70 90 80.5

9.500 58 78 68.0

4.750 35 55 45.5

2.360 20 40 30.5

1.180 12 33 23.0

0.300 6 16 11.0

0.150 4 12 8.5

0.075 2 8 5.0

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Table 3: Basic properties of basalt aggregates and mineral filler

Table 4: Volcanic ash properties

Property Value

Specific gravity 1.98

Liquid Limit N.P*

Plasticity index N.P*

Organic matters Non

Sulphate content Non

Passing # 200 sieve 0%

Clay content Non

Unified classification GW**

AASHTO classification A-1-a

Coefficient of Uniformity 5.60

Coefficient of curvature 1.15

Wearing percentage % 27.00 * Non Plastic ** Well graded gravel

Aggregate Type

Property

Basalt Coarse

aggregate

Basalt Fine

aggregate Mineral filler

Specific gravity 2.789 2.88 2.965

Absorption, % 4.250 - -

Impact value, % 5.000 - -

Abrasion loss, % (Los Angeles) 18.000 - -

21

Table 5: Chemical composition of volcanic ash "reprinted with permission"

Component Percentage

Silicaon Dioxide (SiO2) 47.20

Titanium Dioxide (TiO2) 1.70

Aluminum Oxide (Al2O3) 19.20

Ferric Oxide (Fe2O3) 11.60

Manganese Oxide (MnO) 0.80

Magnesium Oxide (MgO) 4.20

Calcium Oxide (CaO) 8.10

Sodium Oxide (Na2O) 4.80

Potassium Oxide (K2O) 1.20

Phosphorus Pent Oxide (P2O5) 0.50

Lithium Oxide (LiO) 0.50

TOTAL 99.80

Source: (Hosain, M., 1999)

Table 6: Analysis Of Variance (ANOVA) for the obtained OAC results

Source of variation Sum of Squares df Mean Square F Sig. Level

Between Group (SSR) 2.151 3 .717 224.023 0.000

Within Group (SSE) 0.026 8 .003

Total (SST) 2.176 11

22

LIST OF FIGURES:

Figure 1: Followed experimental program

Figure 2: Effect of granular volcanic ash content on the optimum asphalt content

Figure 3: Effect of granular volcanic ash content on the mixes Marshall Stability

Figure 4: Effect of granular volcanic ash content on Marshall Flow

Figure 5: Effect of granular volcanic ash content on the density of the mixes

Figure 6: Effect of granular volcanic ash content on voids in mineral aggregate (VMA)

Figure 7: Effect of granular volcanic ash content on voids filled with asphalt (VFA).

Figure 8: Effect of granular volcanic ash content on the loss of tensile strength

Figure 9: Effect of granular volcanic ash content on creep deformation

Figure 10: Effect of volcanic ash content on fatigue life

Figure 11: Effect of volcanic ash content on resilient modulus (MR)

23

Figure 1: Followed experimental program

Evaluation Criteria:

o Marshall criteria (e.g. stability, flow, VMA, VFA, …etc)

o Indirect tensile strength,

o Fatigue performance

o Dynamic creep

o Resilient Modulus

Conclusions and Recommendations

Control mix:

(0% granular volcanic

ash)

Mix design (four mix design were performed)

Mixes at 10, 20 and

30% granular volcanic

ash contents

Basic properties of collected materials

Results, Analysis and Discussion

Material’s collection:

o Asphalt cement

o Basalt aggregate (coarse and fine)

o Granular volcanic ash

o Mineral filler

24

0

2

4

6

8

0 10 20 30

Volcanic Ash Content (%)

Op

tim

um

Asp

halt

Co

nte

nt

(%)

Figure 2: Effect of granular volcanic ash content on the optimum asphalt content

0

3

6

9

12

0 10 20 30

Volcanic Ash Content (%)

Sta

bil

ity

(K

N)

Figure 3: Effect of granular volcanic ash content on the mixes Marshall Stability

25

8

10

12

0 10 20 30

Volcanic Ash Content (%)

Flo

w (

0.2

5 m

m)

.

Figure 4: Effect of granular volcanic ash content on Marshall Flow

1

1.5

2

2.5

3

0 10 20 30

Volcanic Ash Content (%)

Un

it W

eig

ht

(gm

/cm

3)

.

Figure 5: Effect of granular volcanic ash content on the density of the mixes

26

0

10

20

0 10 20 30

Volcanic Ash Content (%)

VM

A (%

)

Figure 6: Effect of granular volcanic ash content on voids in mineral aggregate (VMA)

Figure 7: Effect of granular volcanic ash content on voids filled with asphalt (VFA).

60

70

80

0 10 20 30

Volcanic Ash Content (%)

VF

A (%

)

27

50

60

70

80

90

100

0 10 20 30

Volcanic Ash Content (%)

Ten

sile

Str

en

gth

Rati

o (%

)

Figure 8: Effect of granular volcanic ash content on the loss of tensile strength

0% Volcanic Ash

0

0.1

0.2

0.3

0.4

0.5

0.6

10 100 1000 10000

No. of load repetitions

Accu

mu

late

d S

train

(%

)

10% Volcanic Ash

20% Volcanic Ash

30% Volcanic Ash

Figure 9: Effect of granular volcanic ash content on creep deformation

28

0

10000

20000

30000

0 10 20 30

Volcanic Ash Content (%)

No

. o

f R

ep

eti

tio

n t

o F

ail

ure

.

Figure 10: Effect of volcanic ash content on fatigue life

0

400

800

1200

0 10 20 30

Volcanic Ash Content (%)

MR

(M

pa)

Figure 11: Effect of volcanic ash content on resilient modulus (MR)