Engineering Computational Methods

Engineering Computational Methods
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30th December 2019

Introduction
There has been a rise in the consumption of concretes over the past years. The number of
concrete user is estimated to be more than 2.5 billion with the use of virgin materials being
considered to have negative effect on the environment (Aly, et al., 2012). The properties of a
good concrete are determined by factors such as compressive strength, bulk density, water
absorption and initial modulus of elasticity (Wongpa, et al., 2010). Optimizing the above-
mentioned properties is expected to result in high quality of concrete that are durable and of great
strength (Temuujin, et al., 2009).
Therefore, studying, identifying and analyzing parameters (Plasticizer, Curing Type,
coarse Aggregate, Fine, curing age and water/binder ratio) that influences these properties should
be taken in consideration. This study sought to identify the relationship between the different
parameters (Plasticizer, Curing Type, coarse Aggregate, Fine, curing age and water/binder ratio)
and the concrete properties (compressive strength, bulk density, water absorption and initial
modulus of elasticity).
The investigation focusses on how different parameters affects the different properties of
the concrete. Analysis is done using Statistical Package for Social Sciences (SPSS) where both
descriptive and inferential statistics is used to unravel the relationship that exists between the
different parameters and the concrete properties. Some of the inferential statistics applied in this
study include; Independent samples t-test and analysis of variance (one-way ANOVA).

Literature Review
General
Concrete can be defined as a strong mass made from a solidifying medium, with the
ingredients being composed of sand, gravel, cement and water. The use of concrete as a building
material has be ongoing for close to 200 years. Its prosperity and ubiquity might be generally
ascribed to:
i. Toughness under threatening conditions
ii. Simplicity with which it very well may be thrown into an assortment of shapes and size
iii. Its easy availability and relative economy.
Concrete is strikingly solid in pressure however it is similarly powerless in strain.
Henceforth, the utilization of plain concrete as a basic material is constrained to circumstances
where noteworthy pliable burdens and strains do not develop (Mustafa, et al., 2011).
High Performance Concrete (HPC) is made with painstakingly chosen top-notch fixings
and improved blend structures. These are grouped, blended, set, compacted and restored to the
most elevated industry measures. Normally, such cements will have a high cement-water ratio of
0.55 to 0.80. Superplasticizers are generally used to make these solid. Nonetheless, quality isn't
generally the essential required property. For instance, an ordinary quality cement with
extremely high sturdiness and exceptionally low porousness is considered to have elite properties
(Xu, et al., 2010).
Raw Materials and Proportions of HPC

This section presents the different materials and their properties as well as the ratios for
obtaining high performance concrete.
Superplasticizer
According to ASTM494, Superplastisizers (SP) are alluded to "as high range water
diminishing admixture which for the most part scatters the water in solid lattice. Three
significant gatherings of Superplastisizers are as per the following: Sulphonated Melamine
Formaldehyde Condense (SMF), Sulphonated Nephthalene Formaldehyde Condense (SNF) and
Modified Lignosulphonates (MLS).The principle reason for utilizing Superplasticizing
admixtures is to lessen the water cement of a blend plan which upgrade solidness of cement. By
utilizing Superplastisizers, we can have flowable solid sort which can be put in hard and blocked
support region (Alnejaili, 2015). A few impacts of Superplastisizers on properties of cement are
as per the following:
 Reduction in interfacial strain.
 Multilayered adsorption of Organic particle.
 Release of water caught among the concrete particles.
 Retarding impact of concrete hydration.
 Change in morphology of hydrated concrete
A study by (Kim, et al., 2010) considered the adsorption conduct of Sulfonated melamine
formaldehyde (SNF) in concrete for various introductory focus and revealed that its fixation
decline quickly in the initial five minutes after its expansion in to all concrete slurries. In the vast
majority of the cases its fixation arrives at a steady worth when adsorption time is more
prominent than 10 min and proposes a connection between the SNF adsorption conduct on

concrete particles and the usefulness of cement. (Lotfy, et al., 2015) led rheological tests on
concrete glue and these tests were utilized to choose the sort and dose of mineral admixtures that
improved solid usefulness. Six distinctive mineral admixtures are tried, just the ultrafine fly
debris gave the best outcomes by diminishing the thickness and yield pressure. These rheological
properties were not accomplished by expanding the water or the high range water decreasing
admixture measurements. The concrete glue rheological information was additionally contrasted
and little droop and bog cone. They presumed that tests are inconsistent for estimating the
functionality.
Curing Type
According to (Samir, et al., 1988),"Curing of cement is characterized as giving sufficient
dampness, temperature, and time to enable the solid to accomplish the ideal properties for its
expected use". At the point when cement is set and completed a legitimate relieving can greatly
affect its quality and strength. Inappropriate restoring of cement may prompt plastic (loss of
dampness when cement is crisp) and dry shrinkage (loss of dampness when solid set) splitting
(Safiuddin, et al., 2007). According to (Al Bakri, et al., 2011) and (Rovnaník, 2010), legitimate
relieving by keeping up proper temperature and dampness will decrease the volume of pores in
concrete by advancement of hydrate items which cause to decrease of porosity in hydrated
concrete glue. Also, keeping restoring concrete in wet condition cause to lessen greater porosity
with time subsequently expecting relieving period of 28days have more quality and solidness
than 7days of relieving. In these examples, two sorts of relieving (dry and wet) utilized and their
consequences for properties of solid will be broke down.
A study by (Farías, et al., 2017) researched the compressive quality of silica seethe elite
cement under various restoring strategies. The solid examples were held under five diverse

restoring conditions and in two unique situations for a time of nine months. The restoring
conditions utilized were water relieving (Control), no restoring, sprinkle restoring, plastic
relieving and burlap restoring. Every one of the last four conditions was presented to two unique
situations indoor condition and open air condition. The quality outcomes were resolved at 1, 3, 7,
14, 28 and 270 days. Finished up indoor examples were more delicate to relieving than those
restored open air. On account of the open air all these restoring techniques give comparable
outcomes because of the bone-dry nature of hot atmosphere.
Water/binder Ratio
The water/binder proportion has the most impact on properties of blend structure and
solidness, quality and life cycle of cement. According to (Tang, et al., 2011), "The proportion of
the measure of water to the measure of concrete utilized (both by weight) is known as the water
to solidify proportion (w/c). These two fixings are liable for restricting everything together". The
handy scope of water/cover proportion is between 0.3 to 0.8, the lower water/fastener proportion
the more quality and firm will be concrete and near 0.8 makes a wet and genuinely powerless
cement. In least difficult manner about water/concrete proportion, the higher proportion cause to
more prominent measure of water which lead to weaken the concrete glue and impact the quality,
porosity, shrinkage and shade of concrete (Tang, 2017).
Coarse Aggregate
A study was done by (Kim, et al., 2010) to experiment on the use of silica smolder in
concrete and assessed the impact of silica rage on the compressive quality and split rigidity and
modulus of versatility of low quality coarse aggregate cement. Concrete specimens were set up
with four kinds of low quality aggregates, to be specific calcareous, limestone, dolomite quartzite

and steel slag. Results demonstrated that, coarse aggregate type impacted the compressive
quality, split rigidity and modulus of versatility of both plain and silica seethe concrete cements
and inferred that fuse of silica smolder upgraded the compressive quality and split elasticity of
cement, particularly that of the low quality limestone total.
Fine Aggregate (sand) Type
A study done by (Rovnaník, 2010) researched the impact of fineness modulus of fine
aggregate on elite cement. The properties of the 6 blends were explored including slump flow,
slump, unit weight and compressive quality, static modulus of flexibility, splitting tensile and
poison's proportion. Fine aggregate with fineness modulus in the scope of 2.18 and 3.24 was
found not to significantly modulus of elasticity and compressive quality.
Curing age
According to (Tang, 2017), curing age has significant effect on the quality of the
concrete. In their study of investigating how the curing age affects the strength of the concrete,
the authors established the curing age affects the strength of the concrete.
Results
Descriptive Statistics
This section presents the summary statistics for the concrete samples. The results are presented
in table 1 below;
Table 1: Statistics
Water/binder
Ratio
Bulk Density Compressive
Strength
Modulus of
Elasticity
Water
Absorption
N Valid 380 380 380 380 380

Missing 0 0 0 0 0
Mean .5246 2190.2158 43.9415 28.7664 6.2869
Median .5000 2186.0000 42.8765 30.1716 6.1526
Mode .65 1799.00a 33.57a 21.07a 5.09a
Std. Deviation .14107 222.98623 11.68861 5.50087 2.13819
Variance .020 49722.861 136.624 30.260 4.572
Skewness .019 .030 .357 -.183 .247
Std. Error of Skewness .125 .125 .125 .125 .125
Kurtosis -1.220 -.840 -.399 -1.360 -.197
Std. Error of Kurtosis .250 .250 .250 .250 .250
Range .45 909.00 57.16 18.96 10.92
Minimum .30 1771.00 19.76 19.52 1.43
Maximum .75 2680.00 76.92 38.48 12.34
a. Multiple modes exist. The smallest value is shown
The average water/binder ratio was found to be 0.52 (SD = 0.14) with the highest ratio
being 0.75 and the lowest ratio being 0.30. The most frequent water/binder ratio was 0.65 with a
median recorded ratio being 0.50. The skewness value for the water/binder ratio shows that the
variable is close to normal distribution (Skewness = 0.019).
For the bulk density, the average was found to be 2190.22 (SD = 222.99) with the highest
bulk density being 2680 and the lowest bulk density being 1771. The most frequent bulk density
was 1799 with a median recorded bulk density being 2186. The skewness value for the bulk
density shows that the variable is close to normal distribution (Skewness = 0.030).
For the compressive strength, the average was found to be 43.94 (SD = 11.69) with the
highest compressive strength being 76.92 and the lowest compressive density being 19.76. The
most frequent compressive density among the samples was 33.57 with a median recorded
compressive strength being 42.88. The skewness value for the compressive strength shows that
the variable is slightly positively skewed (Skewness = 0.357).

For the modulus of elasticity, the average was found to be 28.77 (SD = 5.50) with the
highest modulus of elasticity being 38.34 and the lowest modulus of elasticity being 19.52. The
most frequent modulus of elasticity among the samples was 21.07 with a median recorded
modulus of elasticity being 30.17. The skewness value for the modulus of elasticity shows that
the variable is slightly negatively skewed (Skewness = -0.183).
For the water absorption, the average was found to be 6.29 (SD = 2.14) with the highest
water absorption being 12.34 and the lowest water absorption being 1.43. The most frequent
water absorption among the samples was 5.09 with a median recorded water absorption being
6.15. The skewness value for the water absorption shows that the variable is slightly positively
skewed (Skewness = 0.247).

Frequency distributions
This section presents the frequency distributions for the nominal variables. As can be seen,
majority of the samples (53.7%, n = 204) had undergone wet curing while 46.3% (n = 176) had
undergone dry curing.
Table 2: Curing Type
Frequency Percent Valid Percent Cumulative Percent
Valid
Dry Curing 176 46.3 46.3 46.3
Wet Curing 204 53.7 53.7 100.0
Total 380 100.0 100.0
Concerning the use of plasticizer, majority of the samples had used plasticizer (52.1%, n = 198).
Only 47.9% (n = 182) of the samples had not used plasticizer.
Table 3: Uses Plasticizer
Frequency Percent Valid Percent Cumulative Percent
Valid
No 182 47.9 47.9 47.9
Yes 198 52.1 52.1 100.0
Total 380 100.0 100.0

In relation to the sand type, results showed that there were five categories of sand types with
majority of the samples having sand type A (25.5%, n = 97), this was closely followed by sand
type B (20.0%, n = 76) and type C (20.0%, n = 76).
Table 4: Sand Type
Frequency Percent Valid Percent Cumulative Percent
Valid
A 97 25.5 25.5 25.5
B 76 20.0 20.0 45.5
C 76 20.0 20.0 65.5
D 66 17.4 17.4 82.9
E 65 17.1 17.1 100.0
Total 380 100.0 100.0
For the coarse aggregate type, 3 types were recorded with majority being type C (38.9%, n =
148). Type B was represented by 28.4% (n = 108) while type A had a 32.6% (n = 124)
representation.
Table 5: Coarse Aggregate Type
Frequency Percent Valid Percent Cumulative Percent
Valid
A 124 32.6 32.6 32.6
B 108 28.4 28.4 61.1
C 148 38.9 38.9 100.0
Total 380 100.0 100.0
Majority of the samples had a curing age of 7 days (35.5%, n = 135), 32.4% (n = 123) had a
curing age of 14 days and 32.1% (n = 122) had a curing age of 28 days.
Table 6: Curing Age
Frequency Percent Valid Percent Cumulative Percent
Valid
7 Days 135 35.5 35.5 35.5
14 Days 123 32.4 32.4 67.9
28 Days 122 32.1 32.1 100.0
Total 380 100.0 100.0

Inferential analysis
Comparison based on curing type
This section sought to test whether the different properties of the concrete differ based on the
curing method used (whether wet or dry curing). Results are presented below;
Table 7: Group Statistics
Curing Type N Mean Std. Deviation Std. Error Mean
Water/binder Ratio Dry Curing 176 .5247 .14203 .01071
Wet Curing 204 .5245 .14059 .00984
Bulk Density Dry Curing 176 2198.5341 219.04342 16.51102
Wet Curing 204 2183.0392 226.62414 15.86686
Compressive Strength Dry Curing 176 42.0562 11.02581 .83110
Wet Curing 204 45.5681 12.02226 .84173
Modulus of Elasticity Dry Curing 176 28.7249 5.44983 .41080
Wet Curing 204 28.8022 5.55767 .38911
Water Absorption Dry Curing 176 6.8066 2.23442 .16843
Wet Curing 204 5.8386 1.94822 .13640
Table 8: Independent Samples Test
Levene's Test for
Equality of Variances
t-test for Equality of Means
F Sig. t df Sig. (2-
tailed)
Mean
Differenc
e
Std.
Error
Differenc
e
95% Confidence
Interval of the
Difference
Lower Upper
Water/binder
Ratio
Equal variances
assumed
.165 .685 .014 378 .989 .0002 .015 -.028 .029
Equal variances
not assumed
.014 368.76 .989 .0002 .015 -.028 .029
Bulk Density
Equal variances
assumed
.144 .705 .675 378 .500 15.495 22.957 -29.644 60.634
Equal variances
not assumed
.677 373.14 .499 15.495 22.899 -29.533 60.522

Compressive
Strength
Equal variances
assumed
1.361 .244 -2.950 378 .003 -3.512 1.190 -5.853 -1.171
Equal variances
not assumed
-2.969 376.57 .003 -3.512 1.183 -5.838 -1.186
Modulus of
Elasticity
Equal variances
assumed
.274 .601 -.136 378 .892 -.077 .567 -1.191 1.037
Equal variances
not assumed
-.137 371.85 .891 -.077 .566 -1.190 1.035
Water
Absorption
Equal variances
assumed
4.713 .031 4.511 378 .000 .968 .215 .546 1.390
Equal variances
not assumed
4.466 350.032 .000 .968 .217 .542 1.39
Results showed that among the five properties of the concretes only two properties differed
based on curing method. Compressive strength and Water absorption of the concrete
significantly differs for the samples that had used wet curing and those that had used dry curing.
In relation to the compressive strength, the samples that had Wet Curing (M = 45.57, SD =
12.02, N = 204) significantly differed from those samples that had used Dry Curing (M = 42.06,
SD = 11.03, N = 176), conditions, t(378) = -2.95, p = 0.003.
In relation to the water absorption, the samples that had used Wet Curing (M = 5.84, SD = 1.95,
N = 204) significantly differed from those samples that had used Dry Curing (M = 6.81, SD =
2.23, N = 176), conditions, t(378) = 4.51, p = 0.000.
Comparison based on use of plasticizer
This section sought to test whether the different properties of the concrete differ based on the use
of plasticizer (whether used plasticizer or not). Results are presented below;
Table 9: Group Statistics
Uses Plasticizer N Mean Std. Deviation Std. Error Mean
Water/binder Ratio No 182 .5234 .13762 .01020
Yes 198 .5258 .14450 .01027
Bulk Density No 182 2202.0000 231.23051 17.13995

Yes 198 2179.3838 215.14760 15.28987
Compressive Strength No 182 46.2447 12.18096 .90291
Yes 198 41.8244 10.82191 .76908
Modulus of Elasticity No 182 29.4412 5.37281 .39826
Yes 198 28.1461 5.55745 .39495
Water Absorption No 182 6.2293 2.01788 .14958
Yes 198 6.3400 2.24691 .15968
Table 10: Independent Samples Test
Levene's Test for
Equality of Variances
t-test for Equality of Means
F Sig. t df Sig. (2-
tailed)
Mean
Difference
Std. Error
Difference
95% Confidence Interval
of the Difference
Lower Upper
Water/binder
Ratio
Equal variances
assumed
1.705 .192 -.166 378 .868 -.00241 .01451 -.03093 .02611
Equal variances
not assumed
-.166 377.5 .868 -.00241 .01448 -.03087 .02606
Bulk Density
Equal variances
assumed
2.461 .118 .988 378 .324 22.61616 22.89895 -22.40913 67.64145
Equal variances
not assumed
.985 369.0 .325 22.61616 22.96863 -22.54967 67.78199
Compressive
Strength
Equal variances
assumed
2.604 .107 3.745 378 .000 4.42028 1.18018 2.09974 6.74081
Equal variances
not assumed
3.727 363.2 .000 4.42028 1.18606 2.08788 6.75268
Modulus of
Elasticity
Equal variances
assumed
2.983 .085 2.306 378 .022 1.29510 .56169 .19068 2.39953
Equal variances
not assumed
2.309 377.0 .021 1.29510 .56089 .19224 2.39797
Water
Absorption
Equal variances
assumed
2.867 .091 -.504 378 .615 -.11070 .21979 -.54285 .32146
Equal variances
not assumed
-.506 377.8 .613 -.11070 .21879 -.54091 .31951
Results showed that among the five properties of the concretes only two properties differed
based on the use of plasticizer. Compressive strength and modulus of elasticity of the concrete

significantly differs for the samples that had used plasticizer and those that had not used
plasticizer. In relation to the compressive strength, the samples that had used plasticizer (M =
41.82, SD = 10.82, N = 198) significantly differed from those samples that had not used
plasticizer (M = 46.24, SD = 12.18, N = 182), conditions, t(378) = 3.75, p = 0.000.
In relation to the modulus of elasticity, the samples that had used plasticizer (M = 28.15, SD =
5.56, N = 198) significantly differed from those samples that had not used plasticizer (M =
29.44, SD = 5.37, N = 182), conditions, t(378) = 2.31, p = 0.022.
Comparison based on sand type
This section sought to test whether the different properties of the concrete differ based on the
type of sand (whether type A, B, C, D or E). Results are presented below;
Table 11: ANOVA
Sum of Squares df Mean Square F Sig.
Water/binder Ratio
Between Groups .144 4 .036 1.821 .124
Within Groups 7.399 375 .020
Total 7.542 379
Bulk Density
Between Groups 7306435.852 4 1826608.963 59.364 .000
Within Groups 11538528.453 375 30769.409
Total 18844964.305 379
Compressive Strength
Between Groups 15499.839 4 3874.960 40.052 .000
Within Groups 36280.502 375 96.748
Total 51780.342 379
Modulus of Elasticity
Between Groups 760.150 4 190.037 6.655 .000
Within Groups 10708.243 375 28.555
Total 11468.392 379
Water Absorption
Between Groups 600.461 4 150.115 49.717 .000
Within Groups 1132.277 375 3.019
Total 1732.738 379
Results showed that apart from the water/binder ratio, the rest of the properties significantly
different based on the sand type (p < 0.05).

Comparison based on Coarse Aggregate Type
This section sought to test whether the different properties of the concrete differ based on the
Coarse Aggregate Type (whether type A, B, or C). Results are presented below;
Table 12: ANOVA
Sum of Squares df Mean Square F Sig.
Water/binder Ratio
Between Groups .026 2 .013 .648 .524
Within Groups 7.517 377 .020
Total 7.542 379
Bulk Density
Between Groups 10846334.003 2 5423167.001 255.611 .000
Within Groups 7998630.303 377 21216.526
Total 18844964.305 379
Compressive Strength
Between Groups 5768.588 2 2884.294 23.633 .000
Within Groups 46011.754 377 122.047
Total 51780.342 379
Modulus of Elasticity
Between Groups 387.769 2 193.885 6.597 .002
Within Groups 11080.623 377 29.392
Total 11468.392 379
Water Absorption
Between Groups 197.010 2 98.505 24.182 .000
Within Groups 1535.728 377 4.074
Total 1732.738 379
Results showed that apart from the water/binder ratio, the rest of the properties significantly
different based on the Coarse Aggregate Type (p < 0.05).
Comparison based on Curing Age
This section sought to test whether the different properties of the concrete differ based on the
Curing Age (whether 7 days, 14 days, or 28 days). Results are presented below;
Table 13: ANOVA
Sum of Squares df Mean Square F Sig.
Water/binder Ratio
Between Groups .011 2 .005 .271 .763
Within Groups 7.532 377 .020
Total 7.542 379
Bulk Density Between Groups 9230.960 2 4615.480 .092 .912

Within Groups 18835733.345 377 49962.157
Total 18844964.305 379
Compressive Strength
Between Groups 23310.413 2 11655.206 154.339 .000
Within Groups 28469.929 377 75.517
Total 51780.342 379
Modulus of Elasticity
Between Groups 10301.816 2 5150.908 1664.608 .000
Within Groups 1166.576 377 3.094
Total 11468.392 379
Water Absorption
Between Groups 457.268 2 228.634 67.579 .000
Within Groups 1275.470 377 3.383
Total 1732.738 379
Results showed that apart from the water/binder ratio and bulk density, the rest of the properties
significantly different based on the curing age (p < 0.05).
Discussion of the results
Results showed that among the five properties of the concretes only one property differed based
on curing method. Comparison based on curing type showed that compressive strength and water
absorption varied among the samples that used dry curing and those that used wet curing. In
relation to the compressive strength, the samples that had Wet Curing (M = 45.57, SD = 12.02, N
= 204) significantly differed from those samples that had not Dry Curing (M = 42.06, SD =
11.03, N = 176), conditions, t(378) = -2.95, p = 0.003. In relation to the water absorption, the
samples that had used Wet Curing (M = 5.84, SD = 1.95, N = 204) significantly differed from
those samples that had used Dry Curing (M = 6.81, SD = 2.23, N = 176), conditions, t(378) =
4.51, p = 0.000.
Compressive strength and modulus of elasticity of the concrete significantly differs for the
samples that had used plasticizer and those that had not used plasticizer. In relation to the
compressive strength, the samples that had used plasticizer (M = 41.82, SD = 10.82, N = 198)
significantly differed from those samples that had not used plasticizer (M = 46.24, SD = 12.18, N

= 182), conditions, t(378) = 3.75, p = 0.000. In relation to the modulus of elasticity, the samples
that had used plasticizer (M = 28.15, SD = 5.56, N = 198) significantly differed from those
samples that had not used plasticizer (M = 29.44, SD = 5.37, N = 182), conditions, t(378) = 2.31,
p = 0.022.
Comparison based on sand type showed that apart from the water/binder ratio, the rest of the
properties significantly different based on the sand type (p < 0.05). Similarly, comparison based
Coarse Aggregate Type showed that apart from the water/binder ratio, the rest of the properties
significantly different based on the Coarse Aggregate Type (p < 0.05). Lastly, comparison based
on curing age showed that apart from the water/binder ratio and bulk density, the rest of the
properties significantly different based on the curing age (p < 0.05).
Conclusion and recommendations
The aim of this study sought to investigate on how different parameters affects the different
properties of the concrete. Analysis was done using Statistical Package for Social Sciences
(SPSS) where both descriptive and inferential statistics was used to unravel the relationship that
exists between the different parameters and the concrete properties. Some of the inferential
statistics applied in this study include; Independent samples t-test and analysis of variance (one-
way ANOVA).
Results showed that the different parameters had significant influence on the different properties
of the concrete. For instance, curing type was found to have a significant effect on the water
absorption. Use of plasticizer had significant influence on the compressive strength and water
absorption.

Based on the results, it is recommended that the manufacturers of the concrete need to take into
consideration the different parameters such curing method, curing age, sand type, coarse
aggregate type and the use of plasticizer as they significantly affect the quality of the concrete.
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