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P A M A N T A S A N N G L U N G S O D N G M A Y N I L A
FFECT OF SILICA SAND ON COMPRESSIVE STRENGTH AS PARTIAL
REPLACEMENT OF CEMENT
A Case Study Presented to the Faculty of
College of Engineering and Technology
Pamantasan ng Lungsod ng Maynila
In Partial Fulfillment of the Course
ESC313 – Engineering Probability and Statistics
BENEDICTO, John Rhey A.
DE GUZMAN, Cristine Jhona S.
JACALNE, Gwynelle Q.
LANSANG, Carlo James A.
MAANO, Maria Chelsea M.
RAMOS, Jeslyn Marinella
Bachelor of Science in Civil Engineering
September, 2016
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ACKNOWLEDGEMENT
This study becomes a reality with the help and solicitous support of many individuals. The researchers would like to extend their sincere thanks to all of them. Foremost, they want to praise God Almighty for the wisdom He bestowed upon them, the strength, the peace of mind and good health to be able to finish this research. They would like to express their gratitude towards their family for the encouragement which helped them in completion of this paper. To their friends, block mates who shares their knowledge to the researchers, thank you! To their adviser, Engr. Reynaldo Peñas for imparting his knowledge and expertise about this research. And lastly, the researchers would like to express their gratitude towards each other without one of them they wouldn’t be able to finish this case study.
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LIST OF FIGURES
FIGURE 1. FLOW CHART..................................................................................... 10
FIGURE 2. SCATTER AND PLOT DIAGRAM……………………………………...
FIGURE 3.A ACTUAL RESULT …………………………………………………..V
FIGURE 3.B ACTUAL RESULT ………………………………………………….VI
FIGURE 4. STANDARD MEASURE FOR SPECIMEN ……………………………...VII
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LIST OF TABLES
TABLE 1. DATA OBTAINED FROM THE COMPRESSIVE STRENGTH TEST.............. 11
TABLE 2. CALCULATED DESCRIPTIVE STATISTICS PARAMETERS........................ 12
TABLE 3. REGRESSION AND CORRELATION ANALYSIS....................................... 13
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B. Background of the Study A study on compressive strength model of silica sand cement mortars (with the conformance of Standard Test Method for compressive strength of Hydraulic cement mortar 2 in. x 2 in.) with different variations or amount 0%, 5%, 10%, 15%, and 20% were observed. Silica sand was used to partially replace Portland cement and the mortars were then tested for compressive strength. The results showed that the compressive strength of cement with the replacement of 5% silica sand decreased. However, when the cement was replaced by a 10% of silica sand the said property increased. And decreases when 15% of silica sand was replace but then again increases in 20% of silica sand. As the results are conducted, the researchers yielded that the amount of silica sand to be partially replaced in the cement should be up to 10% as it is the only variation that is accepted using the Testing of Hypothesis. C. Statement of the Problem This study aims to answer the following problems:
- What are the averages of the compressive strengths of each variation that can be used as the parameter of this study?
- What is the relationship between the two parameters (percentage variation against the mean compressive strength for each mix)?
- Is there a significant difference in the control mix and the other percentage variation? D. Objectives
1. General Objective
- To determine the compressive strength parameters using the descriptive statistics: mean, standard deviation and variance.
- To determine the relationship between the two variables (percentage variation against the mean compressive strength for each mix) using the Pearson Moment- Correlation Coefficient and choose the best fit model.
- To know the significant difference in the control mix and the other variations by testing the hypothesis using a 95% confidence level.
2. Specific Objective
2.1 The researchers’ goal is to assimilate if silica sand is applicable as partial replacement
for cement.
2.2 What specific percentage or amount of silica sand would increase the compressive
strength of the cement (0%, 5%, 10%, 15%, 20%) E. Scope and Limitations The researchers wanted to know if there’s an alternative way to reduce the consumption
of cement which causes a high number of CO 2 in the environment. Since the use of cement is
inevitable, the researchers came up with the idea of replacing an amount of cement in a concrete with silica sand. The study will only focus on the characteristics of silica sand which can help to increase the properties of cement such as compressive strength. And to assimilate the possibility of use of silica sand as partial replacement of cement in concrete. F. Definitions of Terms Aggregate - a material or structure formed from a loosely compacted mass of fragments or particles. Cement - a substance used in construction that sets and hardens and can bind other materials together. Compressive strength - the resistance of a material to breaking under compression. Concrete - is a mixture of paste and aggregates, or rocks. The paste, composed of Portland cement and water, coats the surface of the fine (small) and coarse (larger) aggregates. Portland cement - cement that is manufactured from limestone and clay and that hardens under water. Silica sand - is quartz that over time, through the work of water and wind, has been broken down into tiny granules.
Topic: Silica Sand as Fine Material Silica sand is acquired from a raw material (locally available in mamuara village in Kutch district). [2] After washing the raw material, the silica sand is separated by sieve size 1.18 of raw material. From the raw material different size of silica sand are separated by different size of sieve. Sand size of 30 mesh to 80 mesh (500 micron) is used in the glass industries. Sand size 1.18mm to 600 micro can be used in making concrete mix as a substitution of fine aggregate. Concrete produced using silica sand waste as fine aggregate was studied for compressive strength. Silica sand was utilized as substitution of fine aggregate by various percentage for making concrete of M-20, with w/c ratio 0.50 & 0.45. The percentage replacement will be 0 - 70% at an interval of 10% with natural fine aggregates. For making concrete OPC-53 grade cement is used. Cubes will be casted and tested for compressive strength as well as for durability properties. Optimum replacement of silica sand can be used in structural concrete. The study was conducted to observe and learn the effect of silica sand as fine material on concrete. Results of compressive strength of silica sand are as follows: By the substitution of silica sand in concrete, the compressive strength was decreased to 30% replacement and afterwards increased up to 50% replacement after starts decreasing up to 70% replacement, compressive strength was increasing 0.22% at 50% replacement compare to normal concrete for mix – By the substitution of silica sand in concrete, the compressive strength was decreased up to 30% replacement and afterwards increased up to 50% replacement after starts decreasing up to 70% replacement, compressive strength was increasing 1.21% at 50% replacement compare to normal concrete for mix –
SYNTHESIS:
The review of related literature was used to further develop the study to be finished. It gave a theoretical basis for the present study and conveyed ideas that has been established on a topic. Through the information and data provided on International Journal of Research in Engineering and Technology (IJRET) “Use of Silica Sand as Cement Replacement in PPC Concrete” and International Journal for Innovative Research in Science & Technology (IJIRST) “Effect of Use of Silica Sand as Fine Material in Concrete”, it was observed that silica sand has the ability to become a replacement of cement on a concrete at a certain replacement level but also has the ability to diminish the compressive strength at a certain replacement level. Through this related literature, other people working in the same field were identified and the present study was put in a wider perspective as the related literature displayed other opposing views and other possible results.
The proponents used 1:2.75 cement ratio following the ASTM C109. If the cement is now seemed to be tangible enough, it was then placed in the mortar. Something hard were used in order to push and spread the cement equally in the box to avoid getting bubbles and possibly trapped air, the cement block must be pure and doesn’t break easily. In this case, small rectangular shaped plywood was used. 5 mortars were built for each set of trials. Each set were referring to the percentage of silica sand that were replaced on cement powder, with a total of 25 mortars. Marking each mortar to its corresponding percentage of silica sand can prevent confusion. By repeating the process to the remaining trials, this experiment lasts 6 hours. Teamwork is the key for finishing this experiment.
Measurements for the remaining trials; 15 grams of silica sand, 7.8 grams of sand and 277. grams of cement powder were used for trial 2. For trial 3, 30 grams of silica sand, 7.4 sand, and 262.6 grams of cement powder were used. For trial 4, 45 grams of silica sand, 7 grams of sand, and 248 grams of cement powder were used. For trial 5, 60 grams of silica sand, 6. grams of sand, and 233.4 grams of cement powder were used. After 24 hours, checking if the cements were dry or still wet is a must. After confirming the cement was completely dry, it then cured for 7 days and after that the mortars were transported to the testing lab to test its compressive strength.
Figure 1 (Flow Chart)
CHAPTER IV
DATA AND COMPUTATION
A. Presentation of Data Gathered Table 1 Data obtained from the Compressive Strength Test Compressive Strength (at Maximum load and Strength) Percentag e
Units kN MP a kN MP a kN MP a kN MP a kN MP a Sample 1 12. 3
Sample 2 15. 4
Sample 3 13. 2
Table 1 shows the results of the Compressive Strength Test conducted on each sample of mortar cube. The mortar cubes that have been tested are a mix of cement, sand and silica sand. The amount of sand in the mix is fixed while the amount of cement and silica sand varies. It varies as the cement is being replaced by the silica sand with 0%, 5%, 10%, 15%, and 20%. All the mortar cubes undergo a curing process of 7 days. The results presented under the unit of kilonewton (kN) are the maximum load applied while the results under the unit of megapascal (MPa) are the compressive strength obtained. There are 3 samples of mortar cube per percentage of silica sand that replaced the cement. Mortar Cubes having 0% of silica sand as replacement for cement obtained a compressive strength of 4.82, 5.89, and 5.15 megapascal, and the maximum load applied are 12.83, 15.64, and 13.42 kilonewton, for samples 1, 2, and 3, respectively. Mortar Cubes having 5% of silica sand as replacement for cement obtained a compressive strength of 3.97, 3.64, and 3.62 megapascal, and the maximum load applied are 10.02, 9.80, and 9.54 kilonewton, for samples 1, 2, and 3, respectively.
Mortar Cubes having 10% of silica sand as replacement for cement obtained a compressive strength of 3.15, 4.95, and 4.32 megapascal, and the maximum load applied are 8.14, 13.32, and 11.3 kilonewton, for samples 1, 2, and 3, respectively. Mortar Cubes having 15% of silica sand as replacement for cement obtained a compressive strength of 2.97, 2.20, and 2.56 megapascal, and the maximum load applied are 7.07, 5.29, and 6.41 kilonewton, for samples 1, 2, and 3, respectively. Mortar Cubes having 20% of silica sand as replacement for cement obtained a compressive strength of 4.34, 3.57, and 3.33 megapascal, and the maximum load applied are 10.64, 8.89, and 8.38 kilonewton, for samples 1, 2, and 3, respectively. B. Computation B.1. Descriptive Statistics Table 2 Calculated Descriptive Statistics Parameters % of Silica Sand Parameters (in MPa)
Mean ( ´ x
Variance ( Sx
2
) Standard Deviation (^ Sx )
Descriptive Statistics Formula
Mean or Average: ´ x =
∑ x
n
(Equation 1)
Variance: s^2 =
∑ (^ x −´ x ) 2
n − 1
(Equation 2)
Standard Deviation: s =
∑(^ x −´ x ) 2
n − 1
(Equation 3)
Table 2 shows the calculated Mean, Variance, and Standard Deviation for the data gathered, or the values of compressive strength, as per percentage of silica sand in the mortar cube. With the use of Equation 1 for computing the mean, the data obtained were 5.29, 3.74, 4.14, 2.58, and 3.75, for 0%, 5%, 10%, 15%, and 20% of silica sand, respectively.
Table 3 shows the Pearson Product Moment Correlation Coefficient ( r ) for the different
mathematical model (Linear, Exponential, Power, and Hyperbolic).
The Pearson Product Moment Correlation Coefficient ( r ) is obtained by using the
Equation 7; percentage of silica sand against the mean for compressive strength for each mix. As presented, the r-values are all negative, exhibiting an inverse relationship. Meaning, as the percentage of silica sand increases, the compressive strength decreases; and vice versa. The best fit model for the gathered data is the hyperbolic model since, among the four r- values calculated; the absolute value of the r-value for the hyperbolic model is the nearest value to 1. Figure 2 (Scatter and Plot Diagram) B.3. Testing of Hypothesis For 5% silica sand:
a) H 0 :^ μ =5.
H 1 : μ ≠ 5.29 (Two-sided test)
b) α =0.05 (0.025 on each side)
c) Critical region: P ( t <−4.303)∧ P ( t > 4.303)
v = n – 1 (degree of freedom) 0.05 0.1 0.15 0. 0
1
2
3
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Scatter and Plot Diagram Linear Exponential Simple Power Hyperbolic Scatter Percentage of Silica sand
Mean Compressive Strength
v = 3 – 1 v = 2
d) ´ x =3.74 , μ =5.29 , σ =0.20 , n = 3
e)
t =
´ x − μ
σ /√ n
√ 3
f) Since t = -13.423 which is less than -2.920, we should reject the null hypothesis.
For 10% silica sand:
a) H 0 :^ μ =5.
H 1 : μ ≠ 5.29 (Two-sided test)
b) α =0.05 (0.025 on each side)
c) Critical region: P ( t <−4.303)∧ P ( t > 4.303)
v = n – 1 (degree of freedom) v = 3 – 1 v = 2
d) ´ x =4.14 , μ =5.29 , σ =0.91 ,n = 3
e)
t =
´ x − μ
σ /√ n
√ 3
f) Since t = -2.189 which is greater than -2.920, we cannot reject the null hypothesis.
For 15% silica sand:
a) H 0 :^ μ =5.
H 1 : μ ≠ 5.29 (Two-sided test)
b) α =0.05 (0.025 on each side)
c) Critical region: P ( t <−4.303)∧ P ( t > 4.303)
v = n – 1 (degree of freedom) v = 3 – 1 v = 2
d) ´ x =2.58 , μ =5.29 , σ =0.39 , n = 3
e)
t =
´ x − μ
σ /√ n
√^3
