Soil Mechanics Lab Report, Lab Reports of Soil Mechanics and Foundations

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EGC 2173

Soil Mechanics

Falling Head Test

Lab Report

Name Student ID Section

Lim Jin Juen I

Ethan Low I19018100^ 8G

Naghib Swaleh I

Lecturer: Nurul Ain Ibrahim

Lab Report Rubric

Criteria Description Weightage Marks awarded Objectives / Introduction / Theory Good coverage of the theories on the subject and demonstrate the ability to relate its significance to the experiment. 0 5: Theories are copied from the lab manual/no theories 6 — 10: Small amount of research is completed 11-15: Comprehensive research relevant to the topic is done Methodology / Procedures The ability to report the procedures / methods in completing the experiment. 0-5: Procedures are copied from lab manual 6-8: Limited elaboration of the procedures of the experiment 9-10: Complete description of the procedures with figures or other form of illustrations 10 Results / calculations Results to be presented professionally and relevant calculations are shown. Graphs are drawn professionally where necessary. O- 5: Minimum presentation of results 6-10.' Basic results are shown with necessary calculations. 11-15: Further analyses of the results using graphs, tables, etc. Discussions Demonstrate the ability of analysing the results in an independent and critical way. In-depth discussion is presented on the variance of the results with theory, or the effect of the changing of any parameters to 30

Table of Contents Page

• 1. Introduction
• 2. Objective
• 3. Apparatus and procedure
• 4. Results and Calculation
• 5. Discussion
• 6. Conclusion
• 7. Reference
• 8. Appendix

Introduction

The fact that the durability of asphalt concrete is compromised when a pavement has a high air void content has been recognized for many years. Not only do void spaces allow air to enter and oxidize the asphalt cement, but water can also enter and cause freeze-thaw and stripping damage. Brown indicated that to be waterproof, asphalt pavement must have no more than 8 percent voids for fine mixtures and 6 percent voids for coarse mixtures. In 1996, a field study of Virginia pavements found that pavement voids were higher than desirable and visible stripping damage was significant. In addition, it is not uncommon to see damp spots remaining on the surface of Virginia’s asphalt pavements several days after a rain. The Virginia Department of Transportation (VDOT) wanted to know if high voids, stripping, and damp spots indicate permeable pavements and, if so, how permeable the pavements are. There is also concern about the permeability of super pave mixtures. A study by the Florida Department of Transportation (FDOT) in 1996-97 indicated that their Super pave mixtures had high permeability at void levels that were

reasonable for conventional dense-graded mixtures.3 Since VDOT is implementing Super pave in 2000, it is important to determine if permeability is a problem with the Super pave mixtures being used in Virginia.

9) Measuring cylinders of 100 ml, 500 ml and

1000 ml.

10) Scoop.

11) Flat ended tamping rod.

12) Thermometer.

13) Stop clock.

14) Balance readable to 1 g

Procedure: 1) The base plate was assembled, with perforated

base, to the permeameter cell body.

2) The graded filter material was placed in the

bottom of the cell to a depth of about 50 mm.

The surface was levelled and a wire gauze (or

porous disc) was placed on top.

3) The soil was placed in the permeameter in at

least 4 layers, each of which was of a thickness

about equal to half the diameter.

4) Tamp each layer with a controlled number of

standard blows with the tamping rod. The

surface of each layer was levelled before

adding the next.

5) The upper wire gauze (or porous disc) was on

top of the sample.

6) The graded filter material was placed on top of

the disc to a depth of minimum 50 mm.

7) The piston was released in the top plate and

withdrew it to its fullest extent.

8) The top plate was fitted to the permeameter cell

and tightened down in position.

13) Water was allowed to enter the cell and slowly

percolate upwards through the sample until

it emerged first from the air bleed, which was

the closed, and then from the top connection.

14) The length of the sample was measured again

(L2) and the average measurement was

recorded, L (in cm) = ½ (L1 + L2).

15) The control valve was closed and connected the

water supply to the pereameter top connection,

and connected the control valve at the base to

the discharge reservoir, without entrapping air.

16) The inlet reservoir was set at a level little above

the top of the permeameter cell and opened the

supply valve. The manometer pinch cocks

were opened one by one and ensure that no air

is trapped in the flexible tubing as water

flowed into the manometer tubes. The water in all

tubes should reach the level of the reservoir

surface.

17) The permeameter cell was now ready for test

under the normal condition of downward flow.

If a test with upward flow was required, e.g.:

for investigating piping effects, fit the control

valve, connected to the discharge reservoir, to

the top of the cell and connect the water supply

to the base.

18) The height of the inlet reservoir was adjusted

to a suitable level with regard to the hydraulic

gradient to be imposed on the sample.

19) The control valve at the base was opened to

produce flow through the sample under a

hydraulic gradient appreciably less than unity

Calculation

Diameter = 10.5 cm Height = 12 cm Burette area (α) = ) = 0.7854 cm^ specimen diameter (D) = 10.5 cm specimen area (A) = 126 cm^ specimen length (L) = 12 cm Sample 1 time (min) initial head final head ho/hi hydraulic conductivity, K 600 898 824 1.089805825 1.07213E- 600 824 762 1.081364829 9.75192E- 600 762 694 1.097982709 1.16532E- 600 694 624 1.112179487 1.32548E- 600 624 590 1.057627119 6.9848E-

600 590 544 1.084558824 1.01196E-

600 544 496 1.096774194 1.15159E-

600 496 464 1.068965517 8.31419E-

600 464 420 1.104761905 1.24205E-

K avg = 1.07213E- Sample 2 time (min) initial head final head ho/hi hydraulic conductivity, K 600 860 758 1.134564644 1.5739E- 600 758 650 1.166153846 1.91626E- 600 650 592 1.097972973 1.16521E- 600 592 552 1.072463768 8.7215E- 600 552 498 1.108433735 1.28342E- K avg = 1.23778E- Using sample2, 3 rd row: ho/hi = initial head/ final head = 860/ = 1. Permeability, K = = 1.5739E-05 cm/min

1. 7854 ∗ 12

126 ∗ 600 )^ ∗ln

1. 134564644

References

Maupin, G.W., Jr. Follow-up Field Investigation of the Effectiveness of Antistripping Additives in Virginia. VTRC 97-TAR6. Virginia Transportation Research Council, Charlottesville, 1997. Choubane, B., Page, G.C., and Musselman, J.A. Investigation of Water Permeability of Coarse Graded Superpave Pavements. Journal of the Association of Asphalt Paving Technologists, Vol. 67, 1998. Izzo, R.P., Button, J.W., and Tahmoressi, M. Comparative Study of Coarse Matrix Binder and Dense-Graded HMA. Paper presented at the 76th Annual Meeting of the Transportation Research Board, Washington, D.C., January 1997. American Association of State Highway and Transportation Officials. AASHTO Provisional Standards. Washington, D.C., 1998.