WorksheetsITEM 103 — Structure Excavation: Description & Requirements
Total questions: 30
Worksheet time: 15mins
A trench for a pipe culvert encounters hard material below grade. What minimum removal depth is required?
150 mm below pipe invert
300 mm below grade surface
200 mm or 2 mm per 100 mm fill
4 mm per 100 mm fill over pipe
Soft, unsuitable foundation soil is found beneath a non-pipe structure footing. What is the correct remediation approach?
Replace with granular fill placed in 150 mm layers
Pour lean concrete to bridge the weak zone
Add geotextile and keep the original soil
Compact the existing soil with heavier rollers
Which activity is typically excluded from payment for structure excavation in roadway projects?
Excavation requiring dewatering pumps
Excavation within surveyed boundaries
Excavation after installing formwork
Excavation performed outside neat lines
For an aggregate subbase, which material requirement set is acceptable?
Fines passing No. 200 exceed No. 40
CBR at least 25% soaked
Soft, weak stone materials
LA Abrasion greater than 50
For Item 202 crushed aggregate base course, which set of material requirements is correct?
Blend of sand, LA Abrasion ≤40, no CBR requirement
Partially crushed, LA Abrasion ≤60, no fractured face, CBR ≥70%
100% crushed, LA Abrasion ≤45, ≥50% one fractured face, CBR ≥80%
Uncrushed gravel, LA Abrasion ≤50, ≤30% fractured face, CBR ≥60%
If embankment is near subgrade shallower than 1.2 m, what additional step is specified?
Install geotextile underlayment
Apply cement stabilization over 50 mm
Remove sod/vegetation and scarify 150 mm
Increase layer thickness to 300 mm
What is the maximum layer thickness for backfill around structures before compaction?
Place in ≤ 100 mm layers
Place in ≤ 150 mm layers
Place in ≤ 200 mm layers
Place in ≤ 250 mm layers
During construction, why is compacting existing ground to 150 mm depth specified when needed?
To improve surface aesthetics
To provide a firm foundation layer
To reduce equipment fuel usage
To increase moisture content
Which activity should occur immediately after laying each pipe section?
Check joint alignment and seating
Install headwalls and wingwalls
Backfill full height at once
Apply external waterproof coating
How is conduit for pipe culverts typically measured for payment?
By linear meter installed
By cubic meter excavated
By number of joints
By square meter of trench
What is the critical backfill zone height above the pipe crown?
Up to 50 mm
Up to 500 mm
Up to 150 mm
Up to 300 mm
What is the description of Item 200 work scope?
Installing storm drain pipes
Surveying and staking
Placing and compacting subbase
Paving with bitumen
Suitable subbase materials include which type?
Hard, durable crushed stone
Peat and organic material
Uniform beach sand
Soft, silty clayey soil
A subbase material with LL 38 and PI 10 should be:
Rejected for LL > 35
Accepted for PI ≤ 12
Accepted for LL ≤ 50
Rejected for PI < 12
For ITEM 202, what fractured face requirement is specified for particles?
≥ 25% with two faces
≥ 50% with one face
≥ 75% with two faces
≥ 90% with one face
Which statement best differentiates ITEM 201 from ITEM 202 in terms of aggregate processing?
ITEM 201 requires natural gravel only
ITEM 201 prohibits fractured faces entirely
ITEM 202 mandates fully crushed aggregate
ITEM 202 allows uncrushed cobbles widely
For a base course, why is PI limited to 6 in ITEM 201?
To enlarge nominal aggregate size
To enhance asphalt bonding
To increase water absorption
To minimize plastic deformation
A supplier offers aggregate with LL 28, PI 7, CBR 82, LA 48. Which item can accept it?
None meets all limits
ITEM 300 surface course
ITEM 202 crushed base
ITEM 201 base course
Which material property directly relates to particle toughness under traffic?
Liquid limit index
Los Angeles Abrasion
California Bearing Ratio
Plasticity index value
Why might ITEM 202 specify LA Abrasion ≤45 compared to ≤50 in ITEM 201?
Payment is by mass not volume
Surface courses require more flexibility
Natural base allows more fines content
Crushed base needs greater durability
Which statement best describes a single bituminous surface treatment?
Two sprays cutback and one aggregate layer
One spray bitumen and one aggregate layer
Two sprays bitumen and two aggregate layers
One spray emulsion and two aggregate layers
Aggregate used must satisfy which property requirement?
Sand equivalent ≥ 80 and clay content ≤ 3%
Polished stone value ≥ 60 and flatness index ≤ 10
Rounded particle shape and water absorption ≤ 1%
Gradation compliance and LA abrasion ≤ 40
Spraying should be avoided when the surface temperature is below
15°C caution value
20°C minimum threshold
10°C absolute minimum
25°C comfort limit
Why adjust spray rates for specific gravity not equal to 2.65?
Aggregate bulk density changes coverage
Binder viscosity increases with SG
Traffic speed depends on SG
Roller pressure is set by SG
During initial curing, the maximum traffic speed should be
Limited to 40 km/h until binder sets
Restricted to 20 km/h at night
Kept at 60 km/h with escorts
Unlimited if lane is swept
Measurement and payment are based on
Liters of emulsion sprayed
Tonnes of bitumen plus aggregate
Square meters of treated area
Hours of equipment operation
Why is pneumatic-tire rolling preferred for chip seals?
Vibration breaks emulsion quickly
Steel drums prevent binder pickup
High static load reduces voids
Kneading embeds chips uniformly
LA abrasion ≤ 40 ensures
High polish for skid resistance
Adequate durability under traffic wear
Maximum absorption for binder retention
Complete immunity to breakage
A double treatment is preferred when
Traffic volumes are extremely low
Binder cost must be minimized
Greater sealing and texture are required
Aggregate supply is limited
Payment by tonne of bitumen plus aggregate encourages
Overuse of binder to earn more
Faster construction regardless of quality
Ignoring specified gradation limits
Accurate material quantity tracking
