2.0. INTERNSHIP PROJECT REPORT
2.3.16. SITE CLEANING AND DEMOBILIZATION
Upon completion of the soil cement stabilization work, all waste materials which resulted from the work is disposed to a dump site approved by JKR, construction machinery demobilized from the site before and the project handed over for the pavement works.
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Test Conditions; Temperature: 28.6 0C Relative Humidity: 53%
Table 2.4.1-1 Sieve Analysis Results
Figure 2.4.1-1 Particle Size Distribution Curve
Weight Before Wash: 1200.5 grams Weight After Wash: 309.7 grams
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2.4.1.2. Dry Density/Moisture Content Relationship for site soil
Test Condition: Temperature = 29.4 0C, Relative Humidity = 57% & Volume 998.4 cm3
Table 2.4.1.2-1 Dry Density/Moisture Content Relationship for site soil
Figure 2.4.1.2-1 Dry Density / Moisture Content Relationship site soil
Test No. 1 2 3 4 5
Measurement uncertainty for Moisture content (%) 0.33 0.39 0.34 0.33 0.29
Dry Density (Mg/m3) 1.817 1.864 1.908 1.886 1.82
Measurement uncertainty for Dry Density (Mg/m3) 0.005 0.005 0.005 0.004 0.004
1.8
Dry Density/Moisture Content Relationship for Site Soil
MDD = 1.839 Mg/m3
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Table 2.4.1.2-2 Dry Density/Moisture Content Relationship for River Sand fill
Test Condition: Temperature = 29.9 0C, Relative Humidity = 62% and Volume 949 cm3
Figure 2.4.1.2-2 Dry Density / Moisture Content Relationship River Sand fill
Test No. 1 2 3 4 5
Measurement uncertainty for Moisture content (%) 0.28 0.25 0.32 0.26 0.31
Dry Density (Mg/m3) 1.776 1.962 2.155 2.032 1.850
Measurement uncertainty for Dry Density (Mg/m3) 0.005 0.005 0.006 0.005 0.005
1.7
Dry Density/Moisture Content Relationship for River Sand
MDD = 2.156 Mg/m3
ρs=1.186 Mg/m3
OMC = 8.4 %
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Table 2.4.1.2-3 Dry Density/Moisture Content Relationship for imported earth fill
Test Condition: Temperature = 29.9 0C, Relative Humidity = 63% and Volume 949 cm3
Figure 2.4.1.2-3 Dry Density / Moisture Content Relationship for imported earth fill
2.4.1.3. Atterberg Limits
Measurement uncertainty for Moisture content (%) 0.74 0.98 0.67 0.95 0.96
Dry Density (Mg/m3) 1.666 1.734 1.836 1.750 1.619
Measurement uncertainty for Dry Density (Mg/m3) 0.010 0.013 0.009 0.011 0.010
1.6
Dry Density/Moisture Content Relationship for Dark Brown Sandy Clayed Silt
MDD = 1.839 Mg/m3
ρs=2.80 Mg/m3
OMC = 19.5 %
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Test Condition: Temperature = 29.4 0C, Relative Humidity = 57 & Test Date:16/10/2012 Table 2.4.1.3-1 Plastic Limit Test Results
Plastic Limit Test No. 1 2
Measurement uncertainty for Moisture content (%) 3.2 308.0
Average Moisture Content (%) 25.6
Table 2.4.1.3-2 Liquid Limit Test Results
Liquid Limit Test No. 1 2 3 4 5
Figure 2.4.1.3-1 Liquid Limit Graph
Proportion Retained on 425 um Sieve:
Liquid Limit (LL): 55%
Plastic Limit (PL): 26%
Plastic Index (PI): 29%
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2.4.1.4. Unconfined Compressive Strength (UCS) Test Result
Table 2.4.1.4-1 Design Mix (Trial Mix) for Soil-Sand Mixture
Figure 2.4.1.4-1 Ultimate Strength Design Mix for Soil and Sand Mix
0
34 Table 2.4.1.4-2 Design Mix (Trial Mix) for Soil
Figure 2.4.1.4-2 Ultimate Strength Design Mix for Soil
0
35 Table 2.4.1.4-3 Design Mix (Trial Mix) for Sand
Figure 2.4.1.4-3 Ultimate Strength Design Mix for Sand
2.4.1.5. CBR Values before Soil Cement Stabilization Jack/Load rig no. 0.0318 KN/div
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Table 2.4.1.5-1 CBR Values before Soil Cement Stabilization
CH 10, Before Soil Cement Stabilization Jack/Load rig no. 0.0318 KN/div
Mass of Surcharge: 4.5 kg Test date: 5/3/2013 Penetration of Force on Plunger Standard CBR Value
Plunger (mm) Load Guage KN Force (KN) (%)
0 0 Penetration of Force on Plunger Standard CBR Value
Plunger (mm) Load Guage KN Force (KN) (%)
0 0 Penetration of Force on Plunger Standard CBR Value
Plunger (mm) Load Guage KN Force (KN) (%)
0 0 Penetration of Force on Plunger Standard CBR Value
Plunger (mm) Load Guage KN Force (KN) (%)
0 0
37 CH 1010, Before Soil Cement Stabilization
Jack/Load rig no. 0.0318 KN/div
Mass of Surcharge: 4.5 kg Test date: 5/3/2013 Penetration of Force on Plunger Standard CBR Value
Plunger (mm) Load Guage KN Force (KN) (%)
0 0
CH 1260, Before Soil Cement Stabilization (same for CH1510) Jack/Load rig no. 0.0318 KN/div
Mass of Surcharge: 4.5 kg Test date: 5/3/2013 Penetration of Force on Plunger Standard CBR Value
Plunger (mm) Load Guage KN Force (KN) (%)
0 0 Penetration of Force on Plunger Standard CBR Value
Plunger (mm) Load Guage KN Force (KN) (%)
0 0 Penetration of Force on Plunger Standard CBR Value
Plunger (mm) Load Guage KN Force (KN) (%)
0 0
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2.4.1.6. CBR Values after Soil Cement Stabilization
Jack/Load rig no. 0.02577 KN/div
Mass of Surcharge: 4.5 kg Test date: 21/3/2013
Table 2.4.1.5-2 CBR Values after Soil Cement Stabilization
CBR at CH 115, three days after soil cement stabilization Jack/Load rig no. 0.02577 KN/div
Mass of Surcharge: 4.5 kg
Penetration of Force on Plunger Standard
Plunger (mm) Load Guage KN Force (KN) CBR Value 0 0
CBR at CH 125 three days after soil stabilization
Penetration of Force on Plunger Standard CBR Value Plunger (mm) Load Guage KN Force (KN) (%)
0 0
39 CH 150, Age: 3days after Soil Cement Stabilization
Jack/Load rig no. 0.02577 KN/div
Penetration of Force on Plunger Standard CBR Value Plunger (mm) Load Guage KN Force (KN) (%)
0 0
CH 110, Age: 7days after Soil Cement Stabilization Jack/Load rig no. 0.02577 KN/div
Penetration of Force on Plunger Standard CBR Value Plunger (mm) Load Guage KN Force (KN) (%)
0 0
40 2.4.2. DISCUSSION
Sieve analysis is used to determine the gradation of the soil which is a very important element used in the determination of the proportion of the stabilizing agent. A well graded soil makes an excellent soil cement and requires the least amount of cement for its stabilization as compared to a poorly graded soil. The sieve analysis result shows that the soil at the site is well graded as indicated by the particle distribution curve (figure 2.4.1-1).
As shown in (figures 2.4.1.2-1, 2.4.1.2-2 and 2.4.1.2-3), the optimum moisture content is 22.7%, 8.4% and 19.5% for site soil, river sand and imported earth respectively.
Maximum dry density for each soil type is obtained at the respective optimum moisture content. For this reason, mixing of the stabilizing agent into the soil at the time of stabilization will be done at those moisture contents. Water will be added during mixing if the moisture content is found to be lower that the optimum moisture content and the soil will be dried by application of pressurized air if it is too wet. During the process of soil cement stabilization, traces of water in the hand are indications that the optimum moisture content is exceeded.
Since the PI obtained is 29% which is greater than 10% and less than 30%, cement can be used to stabilize the soil at this project site. If PI is found to be more than 30%, it is not advisable to used cement alone to stabilize the soil because it is difficult to mix cement with the soil of PI more than 30% except when lime is first added to reduce the PI and improve workability before adding the cement (Hicks, 2002).
As shown in (table 2.2.4-2), the minimum Unconfined Compressive Strength (UCS) for cement stabilized soil at the age of 7 days is 5.171 MN/m2 and 1.723 MN/m2 for base course and sub-base course or subgrade respectively. Table 2.2.4-2 therefore serves as a reference for the Mix Design of cement content to be used for the subgrade stabilization.
To determine the Mix Design, Samples of soil, sand and soil-sand mixture were thoroughly mixed with 2.5%, 3.5% and 5% cement content until a uniform mixture of soil-cement, sand-cement and soil-sand plus cement at Optimum Moisture Content (OMC) is obtained. The OMC for site soil, river sand fill material and imported earth fill material are 22.7%, 8.4% and 19.5% respectively.
Cubes were then cast and Cube and UCS Tests were conducted at the age of 3 days and 7 days to determine the density and the UCS and the results obtained for UCS test are shown in (table 2.4.1.4-1, table 2.4.1.4-2 & table 2.4.1-4) for soil, sand and soil mixed with sans respectively.
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Table 2.4.1.4-1, table 2.4.1.4-2 and table 2.4.1-4 show that the UCS for 3.5% cement content at the age of 7 days are 2.1 MN/m2 for soil, 2.2 MN/m2 for sand and 4.6 MN/m2 for soil-sand mix. All these values of UCS are higher than the minimum UCS (1.723 MN/m2) for cement stabilized subgrade at the age of 7 days shown in (table 2.2.4-2). This proves that a cement content of 3.5% is sufficient enough to stabilize the subgrade for this project but a cement content of 4% has been used to ensure very stable subgrade is obtained.
The result of CBR test shows a significant increase in the CBR values of the subgrade after soil cement stabilization. The CBR value obtained before cement stabilization is between 12.49% and 42% (table 2.4.1.5-1). The different CBR values obtained before stabilization is due to the different types of subgrade materials and different degree of compaction. For the different soil types, JKR specification recommend a CBR value of
≥5%, ≥30% and ≥80% for soil, sand and aggregates respectively. The effect of the degree of compaction is indicated by the fact that the CBR value obtained is highest at CH10 which is just at the beginning of the new road and the lowest CBR is attained at CH2260 which is close to the end of the road. The highest CBR value obtained at CH10 is due to adequate compaction by the construction trucks used to transport construction materials to increasing chainage along the road.
Just three days after soil cement stabilization, the average CBR value increased to between 78% and 82% and at the age of seven days, the average CBR of the cement stabilized subgrade is 103% as shown in (table 2.4.1.5-2). This CBR value is higher the 80% CBR recommended for aggregate road base course and since CBR value measures the mechanical strength of the subgrade, this high CBR obtained shows how strong the subgrade is after been stabilized with cement. It is this improved strength of the subgrade that results in the reduction of the total thickness of the pavement. The reduction in thickness is as shown in (figure 2.4.2-1) which compares the cross sections of flexible pavement constructed by conventional method to the one constructed with cement stabilization of the subgrade materials
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Figure 2.4.2-1 Thickness of flexible pavement by using soil cement stabilization
Since the subgrade is strong enough to withstand vehicle loading, sub-base and base courses will be eliminated and the binder course is going to be spread directly on the subgrade after an application of prime coat to facilitate its bonding to the subgrade. The surface course will then be overlaid on the binder course after application of tact coat also to facilitate bonding of the two layers. This pavement work is scheduled to start on the 20th April 2013.
Eliminating the base and sub-base courses conserves aggregate material and the environment by eliminating the greenhouse gas emission associated with aggregate mining, procession and transportation to the site. This also eliminates traffic congestion and noise pollution which would have resulted from construction trucks used to haul the crushed stones to the site.
43 Cost Benefit Analysis.
Table 2.4.2-1 Soil Cement Stabilization of subgrade materials
Task Description Length
The sub-contractor, Specialized Pavement Malaysia (SPM) Sdn. Bhd. has accepted to do the soil cement stabilization work with rate and amount shown in table 2.4.2-1 which is the same as that provided in the Bill of Quantity. SPM has its own manpower and all the necessary machineries and equipment to carry out the cement stabilization of the subgrade materials. The cement stabilization of the subgrade materials will be followed by an application of the prime coat and then construction of binder and surface courses.
If conventional method of constructing flexible pavement is used, the subgrade materials will be compacted to 95% or more of the maximum dry density (MDD) without any additive based on JKR specification. As shown in (figure 2.4.2-1a), this compacted subgrade material is normally followed by sub-base, base, binder and surface courses. The sub-base and base courses are constructed of crusher run while the binder and surface courses used the same materials and machineries whether for conventional method or for soil cement stabilization method. The sub-base course can however be eliminated, depending on the strength of the subgrade material after compaction as measured by the CBR value.
If the sub-base course is omitted due to reason stated above, the cost for the road base material including machinery rental is as shown in (table 2.4.2-2). The total cost for the base course is RM 516,390.26which is more than double the total cost when using soil cement stabilization shown in table 2.4.2-1 (RM 245,000.00). Therefore, comparison of the two methods in terms of cost can lead to the conclusion that soil cement stabilization is more cost effective than conventional method
44 Table 2.4.2-2 Crusher Run road base material
Task Description Length
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2.5.0. CONCLUSION AND RECOMMENDATION
2.5.1. CONCLUSION
The Unconfined Compressive Strength of cement stabilized soils increases with increase in cement content as shown in table 2.4.1.4-1, table 2.4.1.4-2 and table 2.4.1-4.
Comparison of the CBR values before and after soil cement stabilization also shows a significant increase in the value of CBR after soil cement stabilization. The CBR of the subgrade before stabilizing with cement is between 19% and 43%. Three days after soil cement stabilization, the CBR value increases to between 78 and 82. A surprising CBR value of as high as 103% is obtained at the age of seven days after soil cement stabilization. This CBR value is higher than the recommended CBR value (80%) for road base constructed of crusher run or aggregate material. For this reason, it is not advisable to have sub-base and base courses, surface course can be constructed directly on the stabilized subgrade because it (the subgrade) is strong enough to withstand the subsequent traffic loading from the vehicle that will be using the road. From the UCS and CBR tests results, it can be concluded that Soil cement stabilization (1) increases the strength of subgrade (2) reduces the cross sectional thickness of flexible pavement thus conserving and/or reallocating road construction material (aggregates).
Analysis of the road construction cost when using soil cement stabilization and conventional method shows that, half of the construction cost is saved by using soil cement stabilization. The construction cost for the road base course constructed using crushed stones (conventional method) is RM 516,390.26 (table 2.4.2-2) which is more than double the construction cost when using soil cement stabilization of the subgrade material shown in table 2.4.2-1 (RM 245,000.00). Based on the cost analysis, it can be concluded that soil cement stabilization is more cost effectivethan conventional method of constructing flexible pavement.
46 2.5.2. RECOMMENDATION
Soil cement stabilization has been used in road pavement, parking areas, slope protection, landfills, foundations of buildings, erosion control and so on for many years.
Although the performance as indicated by the tests results immediately after stabilization is promising, it is recommended that further research be carried out to develop a better understanding of the long-term performance of cement stabilized soils.
Furthermore, specialized machines were used for spreading the stabilizing agent, pulverizing and mixing making it easier to spread at the design stabilizer content and mix at the design stabilization depth. However, the specialized machines cannot be used in a restricted area. For this reason, a research needs to be conducted to develop a reliable construction techniques and specifications for restricted area because a lot of such site conditions (restricted areas) will be encountered in the construction industries.
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3.0. SAFETY TRAINING AND VALUE OF THE PRACTICAL EXPERIENCE
3.1. LESSON LEARNED AND EXPERIENCE GAINED
During the twenty eight (28) weeks of my industrial internship training, I have enjoyed the opportunities to learn from and work with individuals of quite a variety of backgrounds. The people that I have all along worked with or learnt from consists of Malay (the majority), two Chinese and two Indians from I.Z.A Construction Company (my host company), Maryland, JKR (Jabatan Kerja Raya Malaysia), KPP (Kamunting Premix Plant Sdn Bhd) and SPM (Specialized Pavement Malaysia Sdn Bhd). During my training period, the independence afforded to me in tackling issues at site is also worth appreciating. The following are the Lessons that I have learned and Experience that I gained during my internship in I.Z.A Construction Company:
1. Time management, especially in terms of going early to office or site, meetings and coming back from break and lunch on time.
2. During the two months in the office, I have learnt about Tendering and Bill of Quantities (BQ). I have learnt about the methods of and procedure for tendering, I also learned how to determine the quantities of materials from construction drawing by Taking off and how to determine the rate and hence the price of each of the items in the BQ.
3. I also learnt office keeping whereby I fold and file incoming construction drawings and distribute copies to Sub-Contractors, file incoming documents and/or letters and photocopy and file any outgoing documents before they are distributed.
4. Furthermore, I have learnt how to prepare weekly and monthly progress report and to take project progress photos through the help of the Project Engineer Mr.
Zulhelmy. Once the weekly report is done, I e-mail it to the Project Director Mr.
Farouk, the Project Manager Mr. Firdaus, Project Engineer Mr. Zulhelmy and to the Quantity Surveyor Miss Catherine.
48
5. I have also learnt JKR Specification for Road Works and learnt how to read and interpret construction/technical drawings especially for infra works. I can now determine the BRC size and number of reinforcement bars for culvert wingwalls and determine the moisture content of soil at the site using Speedy Test Apparatus.
6. I have an experience of supervising/inspecting site activities for four months. For example, having determine the number of and spacing for reinforcement bars for culvert wingwalls, I double check the number and spacing during actual steelwork at site to confirm that there is no variation but if there is any, an explanation is given to defend the variation. I also check the number of workers and equipment at site, and record down all the materials delivered to the site as well as the number of visitors at the site, their names, positions and companies they come from.
7. I attended a three (3) days (12th – 14th December 2012) course about Microsoft Project 2010 organized by I.Z.A Construction Company during which I have learned how to enter tasks in Microsoft Project 2010 and project scope- work breakdown structure (WBS). I also learnt about activity sequencing, Activity Resource Planning, Setting Calendar in Microsoft Project 2010, Critical Path Method, Schedule Compression (Fast Tracking and Crushing), Project Cost Estimation and Cost Budgeting, plotting Financial and Physical S-Curve, Project Tracking and Project Control- the effects of changing project scope, time and cost.
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3.2. LEADERSHIP, TEAM WORK AND INDIVIDUAL ACTIVITIES
The following are the Leadership, team work and individual activities that I was engaged in during my training period:
1. Tracking project progress in Microsoft Project 2010 weekly, on the 4th, 20th, and 30th of every month and then draw the financial and physical S-Curve for each tracking using Microsoft excel.
2. Supervision of daily activities at site, I jot down daily site activities including the workforce, equipment and visitors at the site as well as materials delivered to the site and the weather condition especially rain and its duration.
3. Taking off to determine quantities of BRC and reinforcement bars for culvert wingwalls
4. Calculating the volume of daily imported earth, I measure and record the height of imported earth and the arrival time of each truck then multiply the measured height by the length and the width of each truck to determine the volume of the imported earth for the truck. By adding the volume of imported earth for all the trucks in a day, the total volume of earth hauled to the site daily is obtained.
5. I also measure and calculate the total area required for turfing with the help of one of the laborers.
6. Speedy moisture content test for imported earth under a close supervision of JKR official Mr. Rama
7. Ensure that slump test is carried out for each truck of concrete before concreting and ensure that concrete cubes are cast to be tested at the age of 7 days and 28days to determine the density and compressive strength of the concrete. The project engineer Mr. Zulhelmy, superviser from JKR Mr. Rama and I go to the KKP office in Kamunting on the 7th and 28th days after each concreting for cube test to determine the density and compressive strength of the concrete.
8. Write weekly progress report
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9. Help the project manager Mr. Firdaus and project engineer Mr. Zulhelmy in preparing monthly report as well as in printing and binding the monthly report. I also attend monthly meeting about project progress with JKR Taiping.
3.3. BUSINESS VALUES, ETHICS AND MANAGEMENT
3.3. BUSINESS VALUES, ETHICS AND MANAGEMENT