Soil 3l6s1k

SOIL 16 3 Major Groups of Soil i Granular i Good load bearing i Permeable i Incompressible i Unchanging strength and volume due to variation in water content ii Composed of gravel and sand i Fine-grained i Poor load bearing i Impermeable i Compressible under sustained load i Subject to change in strength and volume due to variation in water content ii Composed of silt and clay i Organic i Natural moisture content is 100% i Deposited plant matter ii Unsuitable material iii Composed of peat and muck SIEVE

CLASS

Remarks

#

mm

3"

75

gravel

#10

2

sand

#200

0.075

silt

Smooth surface

0.002

clay

Cohesive and plastic when wet

0.001

colloids

16 Common Laboratory Test for Soil i Grading i Combined Sieve Analysis 1 wash test that determines the percentage ing 0.075mm i Hydrometer Analysis 1 calculate the % of grains of various ave. Ø remaining in suspension or those w/c have settled out 2 100 g weight of sandy soil for hydrometer analysis 3 50 g weight of silty/clayey soil for hydrometer analysis i Consistency Tests (Atterberg Limit) i Widely used to control the characteristics of soil which are to be incorporated in roadways ii Liquid Limit 1 min. moisture content at w/c the soil will flow upon the application of a very small shearing force 1 moisture content corresponding to 25 blows, brass cup w/ sample is raised and allowed to drop 10 mm sharply on the base 1 2 rotations/sec 1 Flow Curve - curve in a logarithmic scale where the 25th blow is projected in order to determine LL 2 A total of 3 determinations should be made 3 Highest moisture content in the plastic consistency of fined grained soil 4 100g for LL determination i Plastic Limit

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1 min. MC at w/c the soil can be readily be molded w/o breaking or crumbling 1 the soil thread will begin to break at 3.2mm (1/8") 1 PL= [(wt. of sample -wt of oven dried sample)/wt of oven dried] x 100 2 15g for PL determination 3 Indicates a range of moisture content over which a soil is plastic Shrinkage Limit 1 moisture content by w/c just enough water is added to fill all the voids of an oven dried sample 2 between solid and semi solid states and is defined as the highest moisture content of which the mass attain its volume but continues to lose weight/mass 3 30g sample for SL determination Plasticity Index , PI = LL - PL 1 Indication of % clay content 2 Indicates compressibility of soil 3 Range of water content that a soil is in a plastic state 4 High PI, high degree of compressibility and lower permeability

Shrinkage Index 1. Plastic Limit – Shrinkage Limit Compaction Test (moisture-density relation) i Determines the amount of water to be used when compacting the soil in the field and to obtain the maximum dry density (MDD) and optimum moisture content (OMC) under the specified compacted effort i Soil sample should be air dried 1 Air dry sample under the heat of the sun 1 oven dry at 60˚C 1 Oven Dried sample a 110˚C ± 5˚C (230˚F ± 41˚F)-temp for oven drying soil sample a already oven-dried if it reach its constant weight i CBR (California Bearing Ratio) i Determines bearing ratio of soil when compacted i Determines the potential strength of aggregate ii Sample soaked for 4 days before tested iii CBR of 2 – weak iv CBR of 15 or more – very stable v 10, 30, and 65 blows – no. of blows used in preparation of CBR samples vi 35 kg – weight of sample vii Used to determine strength of subgrade i Los Angeles Abrasion Test (%mass of wear) i % of wear represent abrasion loss ii Determines hardness of CA i unit weight i moisture content i. Ratio of weight/mass of water in the soil to the weight/mass of dry soil after it has been dried to constant weight/mass at temperature of 110˚±5˚C ii. Tested by Calcium Carbide Gas Pressure Unconfined Compressive Strength Test i. Test for clayey soils Direct Shear Test i. Test cohesion and internal friction of soil Vane Shear Test i. Determines the in-situ shear strength of soft to medium clay Bearing Test Triaxial Shear Test Plate Bearing Test ii. Determines soil bearing capacity by loading a steel plate usually 30” dia. Consolidation Test iii. Performed on undisturbed soil sample. i

ii. iii. iv. v. vi. vii. viii.

16 Common Field Test for Soil

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FDT (field density test) - degree of compaction i Sand cone method 1 Sand should #10 and retained #200 i Apparatus for FDT 1 Sand cone (1/2"Ø or 12.77mmØ) 1 Jug (at least 4L) 1 Guide plate 1 Moisture cans 1 Sand 1 Weighing scale 1 Oven w/ temp control 1 Chisel or digging tools 1 Plastic bags 1 Labelling mat'ls i % Degree of Compaction =(Dry Density/ Max Dry Density) x 100 1 Dry Density = Wet Density / [1 + (MC/100)] Moisture content - amount of water present in soil i Natural MC - moisture of undisturbed soil i Hygroscopic MC - moisture of air dried soil i W=(wt. of water/wt. of oven dried soil) x 100 Density Control Strip i 335 sq.m. i Determines the target density before construction Soil Exploration Boring test / Standard Penetration Test(SPT) i measures depth of soil layer ii Most commonly used method in soil exploration iii Extends to at least 1m below proposed grade line iv Made at an average of 250m interval v If the characteristic of bedrock is questionable, the minimum depth of boring into bedrock is 3m.

16 Item 200: Aggregate Subbase Course i Structural layer w/c accepts greater compressive stress than the subgrade, thus reduces the deformation of the concrete pavement under traffic loading 16 Item 201: Aggregate Base Course i Reduces the vertical compressive stress induced by traffic in the subbase and the subgrade i Prevents pumping and provides drainage for PC slabs 16 Base and Subbase i Chief load bearing element of gravel roads i Improper design can lead to structural failure of slabs i Material Requirements i. Consists of hard, durable particles, of crushed stone, crushed slag, or crushed or natural gravel filler of natural or crushed sand or other finely divided mineral matter ii Strength of Aggregates i A well graded aggregate is better than a uniformly graded agg. i The larger the maximum aggregate is, the greater its strength since large particles provide greater interlocking. i The more flat, broken faces the particles have, the greater the strength developed through interlocking. i Compaction increases the shearing strength of aggregate of any size, shape and gradation. i Rough particle surfaces increase strength because of greater friction between them. i Construction Requirement i Before subbase/base construction is started, a trial section of 500m² shall be made to check the suitability of the mat'l and the efficiency of the equipment and construction method.

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-* 16 Soil Classification Tests i Grading/sieve analysis/particle size analysis/mechanical analysis i determines particle size distribution in soil by sieve, hydrometer or a combination

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SIEVE #

OPENING SIZE (mm)

4

4.75

6

3.35

8

2.36

12

1.68

16

1.18

20

0.85

30

0.6

40

0.425

50

0.3

60

0.25

80

0.18

100

0.15

140

0.106

200

0.075

270

0.053

Plastic & Liquid Limit test Group Index = (F-35)[0.2 + 0.005(LL-40)] + 0.1(F-15)(PI-10) i F=ing #200(0.075mm) i GI=0~20 1 0=good subgrade soil 1 20=poor subgrade soil

16 Reducing sample to testing size i Sample splitter (Method A) i Quartering (Method B) 16 Sample for PL & LL test should sieve #40 (0.425mm) 16 Sample for Compaction Test i Method A&B use sample ing #4 (4.75mm) i Method C&D use sample ing #3/4 (19mm) Method A - 4"Ø mold - 25 blows (V-0.000943 m³)

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Method B - 6"Ø mold - 56 blows (V-0.002124 m³) Method C - 4"Ø mold - 25 blows (V-0.000943 m³) Method D- 6"Ø mold - 56 blows (V-0.002124 m³) 16 Compaction test method i AASHTO T-99 (Embankment) i 95% degree of compaction i uses 2.5kg (5.5lbs) rammer w/ a drop of 12" height, i 3 approx. equal layers i. AASHTO T-180 (Subbase and Base) i. 100% degree of compaction i uses 4.54 kg (10lbs) rammer w/ a drop of 18" height i 5 approx equal layers ii. Effects of Proper Soil Compaction ii. Increase in stability and strength ii Minimize future settlement ii Decrease permeability 17 Stages in Compaction i. Swelling Stage 1. Soil grains are forced apart by the water added, thus the grain is reduced ii. Saturation Stage 1. Stage in which all free air is expelled and replaced with water by water, if further pressure is applied to the soil mass, the tendency is to reduce its volume iii. Lubricating Stage 1. Additional water replaces some of the entrapped air and the soil particles move closer together with a resulting increase in density. 17

Specific Gravity - ratio of the wt. in air of an equal volume of water at a stated temp. 18 TEST / ITEM

200 SUBBASE

201 BASE

202 CRUSHED BASE

PI

AASHTO T-90

6 max

12 max

6 max

6 max

LL

AASHTO T-89

30 max

35 max

25 max

25 max

95% min

100% min

100% min

100% min

50% max

50% max

45% max

15cm compacted

15cm compacted

15cm compacted

CBR

25% min

80% min

80% min

GRADING

ing #200 shall not exceed 2/3 of the ing #40

ing #200 shall not exceed 2/3 of the ing #40

ing #200 shall not exceed 2/3 of the ing #40. Filler Material not contain more than 15% retained #4 sieve

COMPACTION ABRASION MAX THK.

MAX SIZE OF AGG

5

104 EMB

AASHTO T-96

20cm loose

3"

2"

17.

19

Soil Stabilization i. Cement or lime ii. Geotextile iii. Chemical ixture (calcium chloride)

16.

Soil Sampling i Shelby tube - thin tube sampler for undisturbed soil i Wax - sealing undisturbed soil sample i Split spoon sampler - tube sampler for disturbed sample i Load Test (Dynamic Load Test) - dynamic test used in the field to obtain empirical results w/c can be used to estimate shear strength and bearing capacity i. Diamond bit - coring bit in rock coring Specific Gravity – ratio of weight in air of an equal volume of water at a stated temperature 18.

Problem Solving i Moisture i Given: 1 Wt. of air dry soil 1 Wt. of oven dry soil 1 Wt. of wet soil i % Hygroscopic Moisture = (Air dry soil - oven dry soil) / oven dry soil i % Natural Moisture - (Wet soil - oven dry soil) / oven dry i

Field Density Test i Given

i

Wt. per cu. of calibrated sand

1532 kg/m3

Wt. of moist soil taken from the hole

7.62 kg

Moisture content of soil

11.1 kg

Wt. of calibrated sand to fill the hole

4.5 kg

Max dry density

2172.7kg/cu.m.

Compute for Compaction i Volume of Hole = 4.5/1532 = 0.002937 cu.m. i Wet density = 7.62/0.002937 = 2,594.5 kg/cu.m i Dry density = wet density / [1+(MC/100)] Dry density = 2594.5 / [1 + (11.1/100)] = 2335.5 kg/cu.m. i Degree of Compaction = dry density / max dry density Degree of Compaction = 2335.5/2172.7 = 1.0749 107.5%

Item Thickness of Layer Level of Surface Crossfall or Camber Longitudinal Grade over 25m Length Surface Irregularity

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TOLERANCES 105 200 ±20mm +20 -30 ±0.5% ±0.1% 30mm

+10 -20 ±0.3% ±0.1% 20mm

201 ±10mm +5 -10 ±0.2% ±0.1% 5mm

300 +15 -5mm +15 -5 ±0.2% ±0.1% 5mm

ITEM 100 : CLEARING AND GRUBBING 1. Removal of undisturbed stumps and roots and non-perishable solid objects with a minimum depth of 1 meter below subgrade. 2. Cogon/talahib shall be cut to a maximum depth of 150mm small tree large tree

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150mm to 900mm diameter with a height of not less than 1.4m over 900mm with a height of not less than 1.4m

ITEM 104 : EMBANKMENT ing 75mm and not more than 15% ing #200 sieve Unsuitable Materials 1. PI>55 2. LL>80 3. Natural density<800 kg/m³ 4. Moisture content>100% ITEM 107 : OVERHAUL Free haul distance of 600m

ITEM 200 : AGGREGATE SUBBASE COURSE Table 200.1 – Grading Requirements Sieve Designation Standard, mm Alternate US Standard 50 2” 25 1” 9.5 3/8” 0.075 No. 200

Mass Percent ing 100 55 – 85 40 – 75 0 - 12

ITEM 201 : AGGREGATE BASE COURSE Table 201.1 – Grading Requirements Sieve Designation Standard, mm

Mass Percent ing

Alternate US Standard

Grading A

50

2”

100

37.5

1-1/2”

-

100

25.0

1”

60 – 85

-

19.0

¾”

-

60 – 85

12.5

½”

35 – 65

-

4.75

No. 4

20 – 50

30 – 55

0.425

No. 40

5 – 20

8 – 25

0.075

No. 200

0 – 12

2 – 14

ITEM 202 : CRUSHED AGGREGATE BASE COURSE Table 201.1 – Grading Requirements

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Grading B

Sieve Designation Standard, mm

Mass Percent ing

Alternate US Standard

Grading A

Grading B

37.5

1-1/2”

100

25

1”

-

100

19

¾”

60 – 85

-

12.5

½”

-

60 – 90

4.75

No. 4

30 – 55

35 – 65

0.425

No. 40

8 – 25

10 – 30

0.075

No. 200

2 - 14

5 – 15

ITEM 300 : AGGREGATE SURFACE COURSE Table 300.1 – Grading Requirements Sieve Designation Standard Alternate Mm U. S. Standard 25 1” 9.5 3/8 4.75 No.4 2.00 No. 10 0.425 No.40 0.075 No. 200

Grading A 100 50-85 35-65 25-50 15-30 5-20

Mass Percent ing Grading Grading B C 100 100 60-100 50-85 55-100 40-70 40-100 25-45 20-50 5-20 6-20

Grading D 100 70-100 55-100 30-70 8-25

When crushed aggregate is called for in the Bill of Quantities, not less than fifty (50) mass percent of the particles retained on the 4.75 mm (No. 4) sieve shall have at least one (1) fractured face. Materials for gravel surface course and crushed aggregate surface course shall have a soaked CBR Value of not less than 25% and 80% respectively as determined by AASHTO T 193. The CBR Value shall be obtained at the maximum dry density and determined by AASHTO T 180, Method D.

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