use of blast furnace slag in road construction. report

Use of Blast-Furnace Slag in road construction
Civil department, NIT Raichur
A
SEMINAR REPORT
ON
“USE OF BLAST-FURNACE SLAG IN ROAD
CONSTRUCTION”
Submitted
BY
Mr.Nagarjun
NIT,Raichur
DEPARTMENT OF CIVIL ENGINEERING
NAVODAYA INSTITUTE OF TECHNOLOGY
RAICHUR-584101

CONTENTS
S.No TITLE Page No.
1 INTRODUCTION 1
2 STRENGTH DEVELOPMENT OF CONCRETES WITH SLAG 3
2.1 Research Significance 3
2.2 Experimental 3
2.3 Experimental Results and Discussion 5
2.4 Analysis of the Results 5
3
DEVELOPMENT OF ENGINEEREDCEMENTITIOUS COMPOSITES
(ECC) WITH SLAG 8
3.1 Materials 8
3.2 Mixing and Curing 8
3.3 Four-point bending and compressive tests 8
3.4 Uniaxial tensile test 9
3.5 Loaded crack width measurement 11
3.6 Results and discussion 11
4 Stabilization Of Expansive Clay 12
4.1 Experimental Studies 12
4.2 Preparation of Samples 13
4.3 Sample Properties 13
4.4 Free Swell Testing Procedure 14
4.5 Test Results 15
4.6 Discussion of Test Results 17
5 Using Blast-Furnace Slag in Road Construction 19
6 SUMMARY 23
7 REFERENCES 24

List of Table
Table
No.
Description
Page
No.
1 Cube compressive strength 4
2 The linear regression analysis results of the strength-time data 7
3 Sample properties 13
Fig
No.
Description
Page
No.
1 Four-point bending test setup 9
2 Uniaxial tensile test set-up 10
3 Compaction of specimen into the consolidation ring 13
4 Variation of t50with stabilizers added 17

Chapter 1
Introduction
10 million tons of blast furnace slag is produced in India annually as a byproduct of Iron
and Steel Industry. Blast furnace slag is composed of silicates and alumino silicates of lime
and other bases. It is a latent hydraulic product which can be activated with anyone- lime,
alkalies or Portland cement.
Lime-GBFS mix as alternate binder to cement, and for its use in mortar, soil stabilization as
well as in concrete. Lime - granulated blast furnace slag (GBFS) binder in 1 : 2 ratio, with
and without 7.5 percent gypsum fulfils the IS requirements for soundness as required for
OPC. With 7.5 percent gypsum final setting time of lime granulated blast furnace slag binder
is reduced from 338 minutes to 270 minutes as compared to lime – GBFS mix without
gypsum. The compressive strength of lime – GBFS sand mortar is improved by 77.0 percent
and 40 percent at 28 and 180 days by the addition of 7.5 percent gypsum by weight of lime-
GBFS binder.
Lime – GBFS soil stabilized mixes (10-25 percent replacement of soil with lime-GBFS mix)
gave CBR values in the range of 48-92 percent and the unconfined compressive strength 15-
40 kg/cm2 in comparison to plain soil which gave CBR value of 7 percent and unconfined
strength 3 kg/cm2 at 28 days. Addition of 7.5 percent gypsum to Lime –GBFS (by weight of
binder) soil stabilized mixes further improved CBR and the unconfined compressive strength
and the values obtained were in the range of 112-266 percent and 29-58 percent respectively.
The hydration of granulated blast furnace slag is slower than that of the ordinary Portland
cement. When mixed with Portland cement, BFS accelerates the hydration of Portland
cement and reacts with the calcium hydroxide, and mixture of the two will retard the rate of

strength development. The degree of retardation depends upon the chemical composition of
the slag and OPC, percentage of slag, temperature and humidity of the environment.
BFS improves the properties of fresh and hardened concrete, such as workability and
durability, for instance, enhancing sulfate attack resistance and decelerating chloride ion
penetration. Besides, the addition of BFS results in a more homogeneous fiber distribution,
because BFS particles provide a driving force for fiber dispersion. Therefore, the use of
limestone powder and BFS in concrete not only reduces the cost and increases the greenness,
but also improves the workability, the mechanical properties and the durability of concrete.
Research on the use of granulated blast-furnace slag in road construction shows that the
strength of the reinforced bed depends on the activity and granule size of the slag, the
quantity and quantity of lime (the activator), the composition of the bed and the relative
content of binder, and also the setting conditions. On the basis of the results, blast-furnace
slag may be recommended as a hydraulic binder for the reinforcement of road materials, with
the addition of lime and other activators

Chapter 2
Strength Development of Concretes with Slag
2.1 RESEARCH SIGNIFICANCE
The compressive strength development of OPC, fly ash, and slag concretes at early ages
subjected to different temperature is greatly affected by the curing temperature. In order to
predict time-strength development, this effect should be taken into consideration.
Compressive strength results of the concretes subjected to different constant curing
temperatures until the age of testing were analyzed according to the hyperbolic strength-age
function.
2.2 EXPERIMENTAL
Throughout this investigation, ordinary Portland cement, ground granulated-blast
furnace slag, and fly ash were used as cementing materials. Composition of OPC, fly ash, and
slag are given in Table 1. The coarse aggregate used was a 10 mm maximum size quartzite
crushed gravel which complied with the grading limits of the BS 882 [8]. The fine aggregate
was 3 mm maximum size and it was obtained from the same source of the coarse aggregate.
During this study five mixes were used.
i) The first one, made by using OPC without any replacement, was used as the mix
control.
ii) The second and third mixes had 30%and 50% of the cement replaced by fly ash.
iii) The fourth and fifth mixes had 30% and 50% of cement replacement with slag.
For all the five mixes the total aggregate/cementitious materials ratio was 6.0 with 33% of
fine aggregates, and the water/cementitious ratio was 0.55. Prior to mixing, the mix
ingredients were stored at the temperatures of 6, 20, 35, 60, and 80ºC for at least 24 hours.

For each temperature 10 standard test cubes (100xl00xl00 ram) were cast for each of the five
mixes. The specimens were kept in their moulds for 24 hours in predetermined constant
temperature curing tanks and then they were & mounded and put back in their curing tanks
until the testing age.The compressive strength was obtained at ages of 1, 3, 7, 28, and 90 days
for water-cured specimens at 6, 20, 35, 60, and 80ºC the test was carried out in accordance
with the requirements.
Table 1-Cube compressive strength
2.3 EXPERIMENTAL RESUUS AND DISCUSSION
The results of the compressive strength tests for five mixes are given in Table 1. At 6 and
20 ºC curing temperature, OPC concrete shows greater strength than other concretes up to the
age of 90 days. They also found that concretes containing slag initially gained strength at a

slower rate than 100% OPC mix. However, at later ages (56 days) the slag mixes did tend
towards achieving their equivalent OPC mix strength. It can be seen from the results of this
research that with a 50% slag replacement level at the 20ºC curing temperature, the slag
concrete did not achieve the equivalent OPC mix strength up to the age 90 days.
From the result we proved that the curing temperature has marked effect on the strength
development of the OPC concrete. Concrete cured at 20 ºC temperature has a higher strength
at 28 days than similar concrete cured at temperatures between 40 and 60ºC Same trend can
be seen from these research results.
2.4. ANALYSIS OF THE RESULTS
It can be seen from the compressive strength of concretes subjected to different
temperature is affected by the curing temperature greatly. In order to predict time-strength
development, this effect should be taken into consideration. Carino [12] suggested a
hyperbolic strength age function that can account for temperature and time effects on strength
development of concretes cured under isothermal conditions.
where
fc = Strength at age t;
to = Age when strength development begins;
fu= Ultimate strength;
k = Initial slope of the relative strength (fc /fu) versus t curve.

The parameters k, to, and fu are all functions of the temperature. Brooks and A1-Kaisi [13]
introduced a power index n, for the (t-to) term to get better fits at high temperatures (40-
60ºC).
Therefore the function becomes:
For each curing temperature, k and fc values were determined by linear regression of
Equation (3) with various combinations of n, until the sum of errors squared were minimized.
It was found that the parameter did not vary consistently with temperature or replacement
level of slag and fly ash, k increases with an increase in temperature up to 60 ºC the
parameter n decreased generally with an increased temperature. The other parameter, which
is the setting time to, decreased with an increase in temperature. The trends of to , decreased
with an increase in temperature.
The prediction of compressive strengths for varying temperatures was done by first
considering the zero strength as either the time at which the initial or final
Setting times occurred (see Table 2). Regression analysis was carried out by considering the
effective age starting from initial and final setting times. It was found that, the final setting
time gave the smaller squared sum of errors for all the temperatures and therefore the
effective age is taken as the time measured from the final set.
Table 2 gives the results of the linear regression analysis according to Equation (3).
Calculated and experimental analysis strength results are compared in Figs. 1 to 5 and it can
be seen that the regression analysis gives good fit to the experimental results.

Table 2-The linear regression analysis results of the strength-time data

Chapter 3
Development of engineered cementitious composites(ECC) with slag
3. Experimental program
3.1 Materials
Two groups of matrix materials were used to produce ECC. The first group included
Portland cement 42.5 N, limestone powder and BFS. The mix proportion of a standard ECC
mixture M45 is used as a reference in the ECC mix design. The second group included BFS
cement and limestone powder.
3.2 Mixing and curing
The matrix materials were first mixed with a HOBART_ mixer for 1 min at low speed.
Then water and super plasticizer were added at low speed mixing. Mixing continued at low
speed for 1 min and then at high speed for 2 min. After fibers were added, the sample was
mixed at high speed for another 2 min.
The fresh ECC was cast into six coupon specimens with the dimension of 240 mm 9 60 mm 9
10 mm and a prism with the dimension of 160 mm 9 40 mm 9 40 mm. After 1 day curing in
moulds covered with plastic paper, the specimens were demoulded and cured under sealed
condition at a temperature of 20_C for another 27 days.
3.3 Four-point bending and compressive tests
After 28-day curing, the coupon specimens were sawn into four pieces with the dimension of
120 mm x9 30 mm x9 10 mm. These specimens were used in fourpoint bending test. The
support span of the four-point bending test set-up was 110 mm, and the load span was 30 mm
as shown in Fig. 4. Two LVDTs were fixed on both sides of the test set-up to measure the
flexural deflection of the specimen. The test was conducted under deformation control at the

speed of 0.01 mm/s. Three measurements were done for each mixture. After 28 days of
curing, the prism specimens were sawn into three cubes with the dimension of 40 x 40 x 40
mm3. These cubes were used for compressive tests. Three measurements were done for each
mixture.
Fig 1 Four-point bending test setup
3.4 Uniaxial tensile test
A uniaxial tensile test set-up was developed for ultra ductile fiber reinforced concrete, such
as ECC, as shown in Fig. 2. The specimen is clamped by four steel plates, one pair at each
end. Each pair of steel plates is tightened with four bolts. Two pairs of steel plates are fixed
on the loading device with four steel bars, two for each pair. Between the pairs of steel plates
and the loading device, there is a ± 3 mm allowance. It is used to diminish the eccentricity in
the direction perpendicular to the plate of the specimen by moving the steel plates along the
steel bar. The tensile force is transferred to the specimen by the friction force between the
steel plates and the specimen. Four aluminum plates, 1 mm thick each, are glued on both
sides of the ends of specimen in order to improve the friction force, to ensure the clamped
area work together and to prevent the local damage on the specimen caused by high clamping
force.

The experimental procedure is described in details hereafter. The coupon specimens were
sanded to obtain a flat surface with a larger bond strength with the aluminum plates. After
cleaning the specimen surface and the aluminum plate with Acetone, the aluminum plates
were glued on the specimen. The glue was cured for 1 day before testing. Before placing the
specimen in the test set-up, two pairs of steel plates were connected to the bottom and the top
parts of loading device, respectively. The lower end of the specimen was first clamped with
the steel plates by tightening four bolts. Then the upper end of the specimen was clamped
with the other pair of steel plates. Finally, two LVDTs were mounted on both sides of the
specimen. The testing gauge length was 70 mm. The tests were conducted under
deformationvcontrol with a loading speed of 0.005 mm/s. More than four specimens were
tested for each mixture.
Fig. 2 Uniaxial tensile test set-up
How to alleviate eccentricity is of most concern in uniaxial tensile testing. The eccentricity
can lead to a bending moment in the cross-section of the testing specimen and therefore an
uneven stress distribution. The larger the eccentricity is, the larger the bending moment is.
With large bending moment imposed on the specimen, cracking starts on the side of the
specimen with high tensile stress, even when the average stress in this cross-section is lower
than the tensile strength. The crack can quickly propagate into

the specimen, due to the stress localization at the crack front and the loss of cross sectional
area. As a result, the measured tensile strength and strain capacity appears far from true
uniaxial tensile properties.
3.5 Loaded crack width measurement
The crack width was measured on the coupon specimens after the uniaxial tensile test.
Three lines parallel to the loading direction were drawn on the specimen. These lines were
uniformly spaced on the width of specimen . Under microscope, the number of cracks
crossing each line was counted. The average crack number of each specimen was calculated
by averaging the number of cracks crossing these three lines. Since ECC deforms several
hundred times larger than the matrix, the tensile deformation of the matrix contributes little to
the overall tensile deformation of ECC. Therefore, the overall tensile deformation of ECC
can be related only to the crack opening. Accordingly, the average crack width w can be
calculated by dividing the measured tensile deformation at the peak load Dl by the average
crack number N.
(4)
The calculated crack width is the loaded crack width. This is different from the residual crack
width in the previous studies , in which the crack width is measured after partial crack closure
due to the relaxation after unloading. The loaded crack width is roughly twice of the
residual crack width.
3.6 Results and discussion
3.6.1Compressive strength
The compressive strength of the ECCs at 28 days is summarized . The increasing limestone
powder content results in a decrease in the compressive strength in M1-4. Comparing the

compressive strength of mixtures M5 and M6, the high cement replacement by BFS causes
little decrease in the compressive strength. The mixtures M3, M5 and M6 with good tensile
property all show compressive strengths higher than 38 MPa. This value can fulfill
engineering requirements in most projects.
Chapter 4
Stabilization of Expansive Clays
4.1 Experimental Studies
The scope of this experimental study was: (a) to determine the effects of GBFS and
GBFSC on grain size distribution, Atterberg limits, swelling potential, and rate of swell of an
expansive soil sample with and without curing, and (b) to investigate the possible
contamination effects from using GBFS and GBFSC in expansive soil stabilization by
leachate analysis.
4.2 Preparation of Samples
An artificial, potentially expansive soil, sample A, was prepared by mixing 85% Kaolinite
(Gs = 2.69) and15% Na-Bentonite (Gs = 2.39) by dry mass. After weighing the constituents,
Na-Bentonite and Kaolinitewere mixed using a trowel. Then the mixture was sieved together
through No. 30 (0.600 mm) sieve to obtain a more homogeneous blend. A preliminary swell
test on sample a resulted in 32.90% vertical swell, indicating a highly expansive soil. To
overcome the swelling potential, ground GBFS (Gs = 2.88), was first added in amounts
ranging from 5, 10, 15, 20 and 25% in dry mass to sample A,
And GBFSC (Gs = 2.89) was manufactured by blending ground GBFS (80%) and ordinary
Portland cement (20%) by mass). GBFSC was added in amounts ranging from 5, 10, 15, 20
and25% in dry mass to sample A.

Prior to mixing, all the constituents were oven dried for 24 h, and ground to pass through a
No. 40 (0.425 mm) sieve. GBFS was ground to 4,000 cm²/g fineness by a crusher. Stabilized
specimens of sample A were prepared by mixing a pre-calculated amount of GBFS or
GBFSC and sample A at a moisture content of 10%. The sample A—GBFS or sample A—
GBFSC blends were compacted directly into consolidation ring at 10% moisture content (Fig.
1) and sealed with stretch film to prevent loss of moisture. Samples were left to cure at 22_C
and 70% relative humidity for 7or 28 days.
4.3 Sample Properties
Hydrometer tests were performed to determine particle size distribution. The LL, PL, PI,
SL (Mercury Method), and specific gravity (Gs) of the samples were determined. The LL, PL
and PI of the untreated and treated samples are given in Table 2.1. All the samples were
classified according to the Unified Soil Classification System (USCS) by plotting test results
on a plasticity chart, and the sample properties are given in Table 2.1
Fig. 3 Compaction of specimen into the consolidation ring
Table 3Sample properties
Samples
Clay
(%) Silt (%) G LL (%) PL (%) PI(%) SL(%)
Soil
classification
Samples A 49 51 2.65 104.5 29.1 75.4 18 CH
95% A+ 5% GBFS 42 58 2.68 81.8 28.8 53 20 CH
90% A+ 10% GBFS 38 62 2.69 81 28.6 52.4 21 CH

85% A+ 15% GBFS 39 61 2.7 78.5 26.9 51.6 21.5 CH
80% A+ 20% GBFS 35 65 2.72 77.4 26.1 51.3 22 CH
75% A+ 25% GBFS 35 65 2.73 75.6 25.1 50.5 23 CH
95% A+ 5% GBFSC 45 55 2.7 106.7 34.6 72.1 34 CH
90% A+ 10% GBFSC 47 53 2.71 83.4 36.8 46.6 36 CH
85% A+1 5% GBFSC 46 54 2.73 69.1 39.1 30 38 MH
80% A+ 20% GBFSC 43 57 2.75 68.8 39.3 29.5 38.5 MH
75% A+2 5% GBFSC 43 58 2.77 65.5 40.3 25.2 39 MH
4.4 Free Swell Testing Procedure
In this experimental study, the ‘‘Free Swell Method’' was used to determine the amount
of swell. Each specimen was prepared to 60 g dry mass. To ease compaction into the
consolidation ring of the oedometer apparatus, 6 ml of water was added to the sample to
obtain 10% water content. The diameter of the consolidation ring was 50.8 mm. To obtain 1.8
g/cm³ bulk density in 34.5 cm³ of specimen volume, 62.1 g of the prepared sample was
weighed and compacted directly into the consolidation ring to a thickness of 17 mm, using a
manual compaction piston. In this way, disturbance caused by using guide rings while
preparing the specimen and then transferring it to the consolidation ring was avoided.
The consolidation ring containing the specimen was placed in the oedometer after placing
filter papers on the top and bottom of the specimen not to clog the porous stones. An air-dry
porous stone was placed on top of the specimen. After the oedometer was mounted on the
loading device, the dial gauge measuring the vertical deflection was set to zero. The specimen
was inundated with water to the upper surface directly, and to the lower surface through
standpipes. A seating pressure of at least 1 kPa applied by the weight of top porous stone and
load plate until primary swell is complete. As soon as the specimen was inundated, swelling
began. The specimen was allowed to swell freely. Dial gauge readings showing the vertical
swell of the specimen were recorded until the swell stopped. These data were used to
calculate the time-swell relations and final swell of each specimen upon inundation. After the
specimen stopped swelling, the final water content was determined in accordance with

ASTM Test Method with designation number D2435-90. Free swell percent was calculated
from Eq 1
Free Swell(%)= 100 dH/H (5)
Where dH is the change in the initial height of the specimen after it is inundated.
H is the original height of the specimen just before the inundation.
4.5 Test Results
4.5.1 Effects of GBFS and GBFSC Addition on the Atterberg Limits of Expansive Soil
The samples treated with GBFS showed a reduction in LL GBFSC caused a slight
increase in LL of sample A with the addition of 5% GBFSC, further additions of GBFSC
caused a decrease in LL of sample A
The PI for samples treated with GBFS and GBFSC showed a similar behavior of a decrease
in PI (Table 2) with an increase in % stabilizer.
Shrinkage limit of the samples decreased with the increased amounts of additives (Table 2).
4.5.2 Effects of GBFS and GBFSC Addition on the Specific Gravity of Expansive Soil
All GBFS (GS = 2.88) and GBFSC (GS = 2.89) additions caused increases in the specific
gravity of samples (Table 2) when compared to the specific gravity of sample A (GS = 2.65).
4.5.3 Effects of GBFS and GBFSC Addition on the Swelling of Expansive Soil
Swell percentage of specimens were decreased by all types and amounts of additives.
Granulated blast furnace slag (5%) addition caused a decrease of 31.1% in the swell when
compared to the swell of sample A. The decrease in swell continued with the increasing
amounts of GBFS in the samples. GBFS (25%) addition caused a decrease of 61.7% in the
swell percentage.

Granulated blast furnace slag cement added samples had the most powerful effect on the
swell amount. Only 5% GBFSC addition caused a decrease of 69.8% in the swell amount.
The decrease in the swell in the specimen containing 15% GBFSC was 80.5%. Specimens
having more than 15% GBFSC content also resulted in decrease of swell up to 81.6%.
4.5.4 Effects of GBFS and GBFSC Addition on the Rate of Swell of Expansive Soil
Rate of Swell is best described by t50. As defined earlier, t50 is the time required to reach
50% of the total swell of the specimen after inundation. Thus, if t50 is larger, rate of swell is
slower. t50 values of specimens were decreased by all types and amounts of additives.
Granulated blast furnace slag added specimens decreased the t50 by amounts ranging from 60
to 90% depending on the amount of GBFS. Decrease in the t50 was gradually increased with
the increased amounts of GBFS.
Granulated blast furnace slag cement added specimens also had a similar effect on t50.
GBFSC (5%) added specimen caused 92.3% decrease while 25% GBFSC added specimen
caused a 98.5% decrease in t50. Decrease in t50 was weakly related to the amount of GBFSC
in the specimens.
4.5.5 Effects of curing on rate the Swell
The results for rate of swell (inversely related to t50) of specimens with and without
curing are shown in (Fig.2). As a result of curing, rate of swell of the samples was generally
increased slightly, the t50 values being decreased.
(t50) without cure > (t50)7dayscuring > (t50)28dayscuring
This order was generally followed by each sample (Fig. 2). Curing shortens the time
necessary for the completion of the 50% swell.

Fig. 4 Variation of t50with stabilizers added
4.6 Discussion of Test Results
The LL, PI, SL and clay content (CC) results can be used to explain the swell results as
follows:
The addition of GBFS (or GBFSC) to the expansive clay:
i) Reduces the CC and a corresponding increase in the percentage of coarse particles
ii) Reduces the LL
iii) Raises the SL and
iv) Reduces the PL of the soil

Additions of GBFS and GBFSC resulted in the formation of aggregations which reduced the
swelling potential of the soil.
The issues are summarized as follows:-
i) At low, normal and elevated curing temperatures, fly ash and slag concretes
developed strength more slowly than OPC concretes.
ii) Slag concretes behaved similarly to OPC concretes after 28 days of age and gave
higher strength at 20ºCthan other curing temperatures.
iii) The increasing limestone powder and BFS contentslead to a smaller average loaded
crack width.
iv) Addition of GBFS and GBFSC to the soils altered the grain size distribution of
expansive soil sample Clay fractions decreased and silt fractions increased upon
adding GBFS and GBFSC.
v) Plasticity index is decreased for all GBFS and GBFSC additions

Chapter 5
Using Blast-Furnace Slag in Road Construction
Road construction has different requirements in terms of both production and operation,
calling for different properties of the Portland cement. In particular, relatively fast setting(2 −
4 h), for example, impairs the technological expediency of the material, especially in the case
of extensive construction work for monolithic cement–concrete road surfaces. The fast setting
of concrete with considerable heat liberation tends to create an internal stress state, which
reduces the crack resistance of the concrete plate; to reduce the stress, temperature seams
must be introduced in the plate. Temperature seams are usually introduced at intervals of 4–6
m; this, in turn, reduces the resistance of the coating to dynamic loads due to the moving
vehicles. As is evident, the fast setting of commercial Portland cement may be attributed to
the high content in the clinker of fast-setting highly basic silicates C3S, aluminates, C3A, and
alum ferrites C4AF, whose total contentis 75–85%. The C2S reaches 50% hydration after180
days; this indicates slow setting. However, on account of its low content (5–25%), this
component has practically no influence on the setting of the Portland cements.
By contrast, slag binders (cements) composed mainly of granulated slag and activators
consist of slow-setting low-basicity silicates C2S (75–85%), which results in slow setting.
Therefore, these are classified as slow-setting binders. Unroasted slow-setting binder largely
meets the requirements of road construction. Slow setting of the binder (2–3 days in normal
conditions) is convenient here. Hence, materials with slow-setting binder will retain their
thixotropic properties for a long period. This means that material may be applied and worked
over more than 2–3 km at a time, without loss of quality. The persistence of the thixotropic
properties will depend on many factors, such as the temperature, the moisture content, the
granular composition of the fillerthe weather, and the operating conditions of the machinery
employed.

The use of sand, gravel, and powder from blast-furnace slag is promising in various asphalt
concretes— for example, in porous asphalt concrete and in gravel– mastic coatings. French
scientists have established that, when using porous asphalt concrete, the noise from vehicles
is reduced by 3 dB. Therefore, the expanded use of this material is recommended, since it
improves both highway safety and environmental conditions. Moreover, this important
innovation improves driver comfort in any weather.
Such coatings ensure
i) Rapid drainage of water from the surface and hence increase road safety during
rainstorms,
ii) By reducing aquaplaning and increasing wheel adhesion to the road.
iii) At night, when the headlights are turned on, there is less reflective glare from the road
surface, with improvement in visibility for the driver.
iv) In many developed nations, the trend is to build highways hat ensure reliable and safe
motion, with minimum ecological impact.
In obtaining porous asphalt concrete with specified properties, the key factor is the interaction
between the bitumen and mineral fillers. A whole set of processes occurring with prolonged
contact of these materials in roadway operation must be taken into account: physical
processes at the bitumen–mineral interface; chemisorption; and filtration of the bitumen and
its components within the mineral grains. In comparison with minerals, blast-furnace slag
contains considerably less SiO2 (34–36%) and more CaO (38–41%).
The distinguishing feature of asphalt concretes based on blast-furnace slag, relative to
traditional rock, is rapid filtration of the binder and its components within the porous slag
material, since the slag is relatively hydrophobic. Bitumen filters through macro- and micro
pores within the asphalt concrete. The presence of micropores at the surface of the slag grains
leads to selective diffusion of the bitumen components. Oil penetrates deep into the
capillaries within the grains; on account of their lower mobility and greater activity, tars
reach smaller depths. Therefore, the surface layer of the bitumen at the slag grains is enriched
with asphaltenets. As a result of the interaction of porous slag’s with bitumen, the bitumen
films rapidly become harder and less lastic, which may accelerate aging of the asphalt
concrete. Therefore, the viscosity of the bitumen should be reduced to some limit. The ease of

deformation of the asphalt concrete may increase here, without loss of strength, and its aging
may be slowed.
Overall, the interaction of bitumen with blast-furnace slag is intense, on account of physical,
mechanical, chemical, electrostatic, and diffusional processes. Therefore, the adhesive
binders at the boundary of the bitumen–mineral material are strong and stable under the
action of atmospheric factors. In addition, the hydraulic activity of the blast-furnace slag
facilitates prolonged setting of the material and the acquisition of additional strength, which
compensates the increased porosity of the asphalt concrete. In additional tests of asphalt
concrete at 75°C, the heating of the road surface in summer is taken into account. It is found
that slag based asphalt concrete is basically free of the deficiencies of traditional asphalt
concrete. With a dense water impermeable supporting layer, no additional layers are required
to compensate for the low carrying capacity of porous asphalt concrete, since it meets and
even exceeds all the physicomechanical requirements on traditional asphalt concrete.
The shear stability or gravel-mastic asphalt concretes with different additives is 10-15%
higher than for traditional asphalt concrete; this indicates high resistance to deformation. And
no special measures are required to clean coatings made of porous and gravel–mastic asphalt
concretes with slag fillers. Over time, the porosity of the asphalt concrete remains practically
constant, on account of the gradual uncovering of surfaces of
Considerable porosity, which is typical of slag materials. Given all the benefits of draining
asphalt concrete based on slag materials, it is recommended for the construction
of all roads in residential areas, so as to increase road safety, reduce noise, and improve the
comfort and visibility of drivers. This recommendation may also be extended to road sections
with sharp horizontal curves.

Chapter 6
Conclusions
• At low, normal and elevated curing temperatures, fly ash and slag concretes
developed strength more slowly than OPC concretes
• Slag concretes behaved similarly to OPC concrete after 28 days of age.
• The strength age relationship is described more accurately by using the hyperbolic
power function
• Slag cement can enhance concrete pavement by improving workability in the plastic
state.
• Increasing strengths and reducing permeability in the harde ned state.
• The increasing limestone powder and BFS contents lead to a smaller average loaded
crack width
• blast-furnace slag is a long-acting binder, which facilitates the solidification of
materials used for road construction, thereby increasing the carrying capacity and
durability of road and runway coatings

References
• O.Eren, (2002). “Strength development of concretes with ordinary Portland cement,
slag or fly ash cured at different temperatures”, Department of Civil Engineering,
Eastern Mediterranean University, Gazimagusa, Kibris, Mersin 10, Turkey, vol
35,page no.536-540
• J. Zhou , S. Qian , M. G. Sierra Beltran G. K. van Breugel “Development of
engineered cementitious composites with limestone powder and blast furnace slag”
Microlab, Faculty of Civil Engineering and Geosciences,Delft University of
Technology, Delft, The Netherlands
• S V Srinivasan,” Use of blast furnace slag and fly-ash in road construction”Indian
highways. Vol. 21, no. 11 (Nov. 1993)
• Erdal Cokca , Veysel Yazici , Vehbi Ozaydin” Stabilization of Expansive Clays Using
Granulated Blast Furnace Slag (GBFS) and GBFS-Cement”, Department of Civil
Engineering, Middle East Technical University, 06531 Ankara, Turkey
• B.A.Asmatulaev.R.B.Asmatulaev,A.S.Abdrasulova,”Use Of Blast-Furnace Slag in
Road construction”, Dortrans Kazakh Scientific-Research and Design Institute,
Almaty, Kazakhstan,AK Kazzhol, Kazakhstan,Vol 37 p.no 722-725
•

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