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IOP Conference Series: Earth and Environmental Science
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Self-Compaction concrete behaviour containing nano fly ash used in
rigid pavement
To cite this article: Dhiaa Neama Jabbar et al 2021 IOP Conf. Ser.: Earth Environ. Sci. 779 012018
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5ISCESD 2021
IOP Conf. Series: Earth and Environmental Science 779 (2021) 012018
IOP Publishing
doi:10.1088/1755-1315/779/1/012018
1
Self-Compaction concrete behaviour containing nano fly ash
used in rigid pavement
Dhiaa Neama Jabbar1, Abdulhadi Meteab Hasan2 and Mohammed Kareem Abed3
IraqAwsat Technical University (ATU), -Al Furat-Technical Institute of Babylon, Al
3,1
Iraq College,Al_Mustaqbal University
2
Mohammed_k1965@atu.edu.iqCorresponding Email:
Abstract. As cement production causes 7% to 8% of global carbon dioxide emissions, many
efforts have been made to reduce the consumption of cement. Using pozzolan (usually fly ash)
as additional material with cement is one of these methods. In this paper, the impact of adding
Nano fly ash as a partial substitution of cement weight was studied in self-compacting concrete
for rigid pavement. Three replacement ratios were used which are (5,10 and 15) % of cement
weight. The results showed that the greater substitution ratio gave better workability with higher
d slump flow value and better passing ability of concrete. Also, the use of Nano fly ash improved
the mechanical properties of the self-compacting concrete by increasing the compressive and
splitting tensile strength. The best increase in the strength at the replacement ratio (10%) of
cement weight. The slump flow for concrete mixes is between (658 to 732) mm and the
compressive strength was improved with the increase of Nano fly ash replacement (10%) by
about (20%) compared with conventional concrete. The rigid pavement strength able to provide
a surface of good riding quality.
Keywords: self-consolidating concrete, Self-compacting concrete, Nano fly ash, concrete
compressive strength, Concrete splitting tensile strength.
1. Introduction
Fly ash can be used as an auxiliary cementing material for the production of Portland cement concrete.
Fly ash is a manufacturing waste that needs to be recycled or disposed of in an appropriate manner.
Generally, fly ash is added to structural concrete in a proportion (5-30%) of the weight of cement, but
as high as (70%) is added for mass concrete. It involves Nano fly ash and conventional fly ash. There
are many benefits of using fly ash in concrete, it can improve the performance of concrete in the
hardened and fresh case also it is cost-effective. (Nanyakkara k. et al., 2017 and Alaa A. et al., 2018).
Self-consolidating concrete may be known as concrete that must flow and compacted under its weight
and can be filled the formwork even in the being of intensive reinforcement while preserving
homogeneity and without any further consolidation. All elements that control its filling capacity, passing
capacity, and anti-segregation properties want to be precisely controlled to secure that its placement
capacity is still acceptable. The high fluidity of self-compacting concrete is due to very careful mixing
ratios, usually, fine powder and cement are used to replace much of the coarse aggregates, and chemical
admixtures are added.
Sri, T., and Kartikas (2014) studied the possibility of replacing cement with fly ash. In this study, the
percentage of Nano fly ash used is (0, 2.5, 5, 7.5, 10, 12.5, and 15) %. The results show that when the
percentage of fly ash is less than 20%, the compressive resistance of the mortar made of fly ash will be
slightly lower than that of cement mortar under 20 days, while the strength at 90 days will be
significantly improved. Roychand et al. (2016) investigated the characteristics of high-capacity ultrafine
fly ash class F by substituting (80%) cement weight. The results showed that the use of silica fume and
a large volume of ultra-fine fly ash improved the resistance of cement mortar (for 7 and 28) days. Alaa
et al. (2018) Realized the influence of Nano fly ash on the performance of cement mortar. The results
show that the concrete structure has been significantly improved. With the development of the calcium
silicate hydration (C-S-H) stage, the disappearance of porosity, high density, and improvement of
5ISCESD 2021
IOP Conf. Series: Earth and Environmental Science 779 (2021) 012018
IOP Publishing
doi:10.1088/1755-1315/779/1/012018
2
compression and thermal properties. Seong et al. (2014) reported the comparison between Nano flies
ash and traditional fly ash. The results shows that the mortar with smaller binder particles has superior
carbonization resistance and provides a strong dense charging influence. Hussein et al. (2018)
investigated the uses of Nano-waste materials with fly ash in concrete production. In this study, Nano
fly ash from waste show worthy pozzolanic properties. This is due to the high specific surface area, the
high silica content, and as well as low ignition loss. As a result, using Nano size materials can decrease
the cement demand in the production of concrete. Veerendra Kumar et al. (2019) studied the effect of
Nano-silica on the self-compacting mortar with high-volume fly ash. The results indicated that a loss of
compressive resistance due to high fly ash volume with a flow capacity of (240 to 260) mm. Anayak
kara (2017) studied the effect of a high-proportion of nano-silica and fly ash on concrete mixtures. The
results showed that in the early stage of concrete, the compressive strength decreased with the increase
of the percentage of fly ash, and the replacement of (30%) fly ash had sufficient strength at age of 100
days. Gaurav et al. (2016) studied the strength characteristics of geopolymer concrete rigid pavement
using low-calcium fly ash, coconut fibre, and NaOH solution. The results display that the concrete age
has no effect on the compressive resistance of geopolymer concrete and indicating that coconut fibre is
a suitable material for road construction.
Nagsh et al. (2012) believe that using fly ash in concrete road construction can resolve the disposal
trouble and reduce costs of construction without reducing the strength. Vallabumi et al. (2018)
investigated the effect of replacing different percentages of fly ash (0, 20, 30, 40, 50, and 60)% with
cement. The results show that, compared with ordinary concrete, the strength of the concrete sample is
increased by more than 30%.
2. Materials
2.1. Cement
Sulphate resisting Portland cement (SRPC) grade 42.5 type Of Tasluja Cement Companies was used
identical to the Iraqi standard (IQS No.5/ 1984). The specific surface, specific gravity, initial and final
setting times of cement were (3438 cm2/g, 3.15, 105 minutes and 260 minutes) respectively.
2.2. Fine Aggregate
Al-Ulchaidar sand was used according to Iraqi standard (IQS No.45/1984) with water absorption, bulk
specific gravity, sulphate content as SO3% and fineness modulus were (0.9%, 2.63, 0.23% and 2.30)
respectively.
2.3. Coarse Aggregate
Crushed coarse aggregate with a nominal particle size (5-20) mm, water absorption, bulk specific
gravity, fineness modulus and sulphate content as SO3% were (0.5%, 2.67, 6.52 and 0.041%)
respectively.
2.4 Superplasticizer
Superplasticizer (SP) can be used to reduce water demand for mixes. SP improves the flow properties
of concrete. In this study, Glenium 51 has been used to prepare self-compacting concrete mixes.
2.5 Fly ash
Fly ash bought from Evonik Company, Turkey was used as an auxiliary cementing material with three
replacement ratios were (5, 10 and 15) % of cement weight. Table 1 shows Nano fly ash properties that
were used in this study.
5ISCESD 2021
IOP Conf. Series: Earth and Environmental Science 779 (2021) 012018
IOP Publishing
doi:10.1088/1755-1315/779/1/012018
3
Table 1. The composition of Nano fly ash
Item
Value
SiO2
63.54
Al2O3
16.62
F2O3
4.3
CaO
6.38
MgO
1.86
Na2O
2.60
K2O
1.17
Loos in ignition
1.64
Specific gravity
2.3
Particle size
100
3. Experimental Program
3.1. Mix Proportion
The mix ratio of self-compacting concrete must meet the standards of filling capability, passing capacity,
and segregation confrontation. According to the indicative typical range of (EFNARC, 2002), the initial
mixture composition was prepared by volume. After estimating the powder, water, and coarse aggregate
content, the absolute volume method is used to calculate the sand that balances the amount of the other
materials. Trial mixing was carried out in the laboratory to verify the properties of the initial mixture to
determine the appropriate SP dose. Then make necessary adjustments to the composition of the mixture
until the satisfactory self-compacting ability is obtained by evaluating new concrete tests. Accordingly,
the four self-compacting concrete mixtures shown in Table (2) were arranged, namely (FL0, FL5, FL10,
FL15).
Table 2. Mixture proportion of the rigid pavement concrete.
Mix
description
Cement
kg/m3
Nano fly
ash
kg/m3
Sand
kg/m3
Gravel
kg/m3
Water
kg/m3
SP L/m3
w/p
ratio
FL0
450.0
00.0
800
800
157.5
6.5
0.35
FL5
427.5
22.5
800
800
157.5
6.5
0.35
FL10
405.0
45.0
800
800
157.5
6.5
0.35
FL15
382.5
67.5
800
800
157.5
6.5
0.35
3.2. Specimens preparation
An electric mixer was used to prepare the mixture. Coarse and fine aggregate, cement, and Nano fly ash
were well blended in a dry state. Then one-half of the mixing water was introduced to the mixture and
the all matters were well mixed. After that superplasticizer with the residual water was added then the
concrete was mixed for 3 minutes.
After the blending process was completed, the fresh concrete was tested to determine the workability
factors. 6 cylinders and 12 cubes were cast from each mix. Wet concrete was molding in one layer
without being compacted. Use a hand trawl to smooth the upper surface of the fresh concrete sample.
After 24 hours, the molds were stripped and the samples were placed in a curing water tank according
to (BS. 1881: Part 111).
5ISCESD 2021
IOP Conf. Series: Earth and Environmental Science 779 (2021) 012018
IOP Publishing
doi:10.1088/1755-1315/779/1/012018
4
3.3 Specimens tests
3.3.1 Fresh concrete tests. There are many methods to test the characteristics of fresh self-consolidating
concrete, such as U-box and slump flow tests. If the necessities (passing capacity, filling capacity, and
segregation resistance) are met, the concrete mixture can only be categorized as self-consolidating
concrete, Slump flow test finished ensuring the flowability of rigid pavement concrete according to the
EFNARC (2002) guidelines. It can be obviously detected that Nano fly ash substitution to the cement
had improved flowability.
3.3.2 Hardened concrete tests
• Compressive Strength test: Cubes used for this test have a dimension of (10×10×10) cm. The test
had been carried out as stated by BS.1881: part 116. Three specimens were tested at each age for
each mix.
• Splitting Tensile Strength test: This test was carried out using an indirect method of testing
according to BS.1881: part 117. Two cylinders with dimensions of (10×20) cm had been tested at
each age for each mix and reported the average value.
4. Results and Discussion
4.1. Fresh concrete
Nano fly ash particles are artificial pozzolan spherical materials with very high fineness spherical
particles with a size range of (100 nm). Most natural pozzolans can be made into viscous mixtures to
maintain aplastic consistency and increasing workability. By producing a more plastic paste for mixing,
the concrete is easy to consolidate and flow freely under its weight.
Tables 3 and 4 and Figures 1 and 2 show that with the increase of Nano fly ash as a substitute for
cement, the filling capacity and passing capacity of new concrete increase. The slump flow rate
increased from (650) mm for the conventional mixture to (732) mm for the mixture containing (15%)
fly ash and reduce the filling height from (7mm) for the reference concrete to (zero) for (15%) Nano fly
ash concert. It can be clearly seen from the results that adding Nano fly ash into rigid pavement concrete
can significantly promote and enhance the workability of fresh concrete.
4.2. Hardened concrete
Concrete containing pozzolan typically provides higher strength at later ages. The impact of natural
pozzolan on the mechanical properties of rigid pavement concrete varies markedly with the properties
of the particular pozzolana.
Results of compressive resistance investigation show in Table (5) and figure (3). The results are
conducted by testing the compressive strength development of rigid pavement concrete at the ages of
(7, 28, 56, and 90) days. The results show that the rate of strength development of the concrete with
Nano fly ash is slower in compressive strength to that of the control specimen at early ages (7 and 28)
days. After that (56 and 90) days age, the concrete specimen containing Nano fly ash gained higher
strength because of the existence of silicon oxide which can interact with (CH) to form. (C-A-H) and
(C-S-H). These supplemental hydrated outputs fill the pores and Produce more a dense matrix that
improves the concrete strength. It can be seen from Table (6) and Figure (4) that the higher values of
splitting tensile strength in concrete specimens containing Nano fly ash compared with reference
concrete. This is because of the high pozzolanic effectiveness of Nano fly ash and its role as a filler,
thereby improving the interface transition zone and providing firm contact points between aggregated
particles. It must be noted that the high specific surface of the Nano fly ash means that the material is
easily ready to react with calcium hydroxide. The very fine Nano spherical particle is the main reason
for its high pozzolanic reaction. (Alaa, A. et al., 2018 and Mohammed, K., 2018).
5ISCESD 2021
IOP Conf. Series: Earth and Environmental Science 779 (2021) 012018
IOP Publishing
doi:10.1088/1755-1315/779/1/012018
5
Table 3. Slump flow values (mm)
Mix registration
Slump flow (mm)
FL0
658
FL5
687
FL10
702
FL15
732
Table 4. Filling height values (mm)
Mix registration
Filling height (mm)
FL0
7
FL5
2
FL10
0
FL15
0
Figure 1. The relation between slump flow with Nano fly ash percentage
Figure 2. The relation between filling height with Nano fly ash percentage
Table 5. Compressive strength of rigid pavement concrete (MPa)
Mix registration
Age (days)
7
28
56
90
FL0
31.6
58.0
61.4
63.8
FL5
28.2
56.7
63.2
68.5
FL10
26.5
56.0
69.0
76.4
FL15
23.0
52.8
62.7
64.2
600
650
700
750
FL0 FL5 FL10 FL15
Slump Flow (mm)
Nano Flay Ash %
Slump Flow (mm)
0
2
4
6
8
FL0 FL5 FL10 FL15
Filling Hieght (mm)
Nano Flay Ash %
Filling Hieght (mm)
5ISCESD 2021
IOP Conf. Series: Earth and Environmental Science 779 (2021) 012018
IOP Publishing
doi:10.1088/1755-1315/779/1/012018
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Table 6. Splitting tensile strength of rigid pavement concrete (MPa)
Mix registration
Age (days)
28
56
90
FL0
5.34
5.72
6.18
FL5
5.51
5.84
6.21
FL10
5.93
6.32
6.50
FL15
5.86
5.96
6.33
Figure 3. The relationship between the percentage of Nano fly ash and the compressive strength
Figure 4. The relation between the percentage of Nano fly ash and the splitting tensile strength
Due to high compressive and tensile strength (over 64 and 6.0) MPa, respectively used in rigid
pavement concrete slab, and hence the pavement structure can resist unlimited and carrying the same or
very heavy traffic density loads during the service design life or rigid pavement concrete. High rigidity
of concrete pavement of highway application tends to distribute the cumulative vehicle load over a
relatively wide area of subgrade and preferred for high traffic volume and heavy resistance to water
penetration, thus, the key factor that could affect the susceptibility of the road to loading.
5. Conclusions
It is clear, the advantage of the partial cement substitutes with Nano fly ash is very important and
beneficial economically, environments and preserving of natural material by replacing a quantity of
waste material with cement. Also, from this study, with the respect to the use of Nano fly ash as a
replacement for cement, the following conclusions can be pointed out:
0
20
40
60
80
100
FL0 FL5 FL10 FL15
Compressive Strength
(MPa)
Nano Flay Ash %
Age 7 days
Age28 days
Age 56 days
Age 90 days
0
2
4
6
8
FL0 FL5 FL10 FL15
Splitting Tensile Strength
(MPa)
Nano Flay Ash %
Age28 days
Age 56 days
Age 90 days
5ISCESD 2021
IOP Conf. Series: Earth and Environmental Science 779 (2021) 012018
IOP Publishing
doi:10.1088/1755-1315/779/1/012018
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1- The fresh concrete flow to a great distance and remain homogeneous without segregation.
2- The values of slump flow and filling height for rigid pavement concrete mixes were improved
from (658 to 732) mm and (0 to 7) mm respectively.
3- The increase of the Nano flies ash percentage addition from (zero to 15) % lead to an increase in
the compressive and splitting tensile strength from (63.8 to 76.4) MPa and (6.18 to 6.50) MPa
respectively at the age of 90 days.
4- The results obtained display that the Nano fly ash has useful influences on compressive and
splitting tensile strength, especially at the later ages.
5- Increase in service life and improved performance of the pavement due to the high compressive
and tensile strength of rigid pavement concrete.
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5ISCESD 2021
IOP Conf. Series: Earth and Environmental Science 779 (2021) 012018
IOP Publishing
doi:10.1088/1755-1315/779/1/012018
8
[17] BS. 1881: part 117 1983 Method for determination of tensile splitting strength (British
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