1. Siteworks & Earthworks

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Questions and Answers

Which of the following best describes geosynthetics?

Materials used exclusively for erosion control.

Synthetic components used with earth materials. (correct)

Natural materials used for earth construction.

Organic textiles used for drainage.

What is the primary use of geotextiles in reinforcement?

To provide tensile strength to low load-bearing soil. (correct)

To improve the aesthetic quality of construction.

To facilitate drainage of heavy rains.

To prevent erosion in wet areas.

What function do geotextiles serve when used as a separator?

To control soil erosion on slopes.

To reinforce weak soil layers.

To filter water through fine soil particles.

To prevent the migration of dissimilar materials. (correct)

In which scenario would erosion control geotextiles be primarily used?

To protect slopes and drainage features. Signup and view all the answers

Which of the following is NOT a category of geosynthetics?

Geobags Signup and view all the answers

What is the role of subsurface drainage geotextiles?

To provide filtration around edge drains or underdrains. Signup and view all the answers

How do containers filled with stone benefit construction in inaccessible areas?

They allow for flexible, permeable structures to be formed. Signup and view all the answers

Which of the following materials are geotextiles commonly made from?

Polyester or polypropylene Signup and view all the answers

What secondary function do erosion control geotextiles provide when used with stone lining?

Offering separation between dissimilar materials. Signup and view all the answers

What is the primary objective of establishing chemical barriers in construction?

To establish a continuous termite barrier between soil and the structure Signup and view all the answers

How much termiticide should be applied per linear foot when creating vertical barriers?

4 gallons for every 10 linear feet Signup and view all the answers

What is the role of hexaflumuron in the Colony Elimination (Bait) System?

To continuously attract termite workers to eliminate their population Signup and view all the answers

What is the typical application method for horizontal barriers of termiticide?

Coarse spray at low pressure Signup and view all the answers

What is a defining characteristic of rigid pavements?

Made of reinforced concrete slabs or paving units Signup and view all the answers

Which type of pavement is most affected by the bearing capacity of the sub-grade?

Flexible pavement Signup and view all the answers

What is a common method of treating basements and crawl spaces for termites?

Digging trenches and applying termiticide to trenched areas Signup and view all the answers

Which of the following materials is classified under the Unified Soil Classification System (USCS) as gravels?

Soil with 50% of coarse fraction retained on No. 40 sieve Signup and view all the answers

What is the function of the liquid limit test in Atterberg limits?

To identify the point when soil changes from plastic to liquid state Signup and view all the answers

What is a primary purpose of using riprap in construction?

To protect structures against erosion and scouring Signup and view all the answers

Which of the following describes 'borrow fill' correctly?

Soil that is sourced from an approved pit or quarry Signup and view all the answers

What do the Atterberg limits help determine about soil?

The moisture content range affecting soil behavior Signup and view all the answers

Which of the following best defines the plastic index of soil?

The difference between the liquid limit and plastic limit Signup and view all the answers

What characterizes gabion systems in construction?

Stone-filled wire containers designed to stabilize soil Signup and view all the answers

Under the AASHTO soil classification system, what size particles are defined as 'boulders'?

Particles larger than 75 mm Signup and view all the answers

What is the primary application of sediment control geotextiles?

Silt fence applications Signup and view all the answers

Which property is NOT associated with membrane roofing materials like EPDM?

High tensile strength Signup and view all the answers

What do geocomposites consist of?

Combination of geosynthetic components Signup and view all the answers

Which materials are used to manufacture geomembranes?

High-density polyethylene (HDPE) and polyvinyl chloride (PVC) Signup and view all the answers

What is the function of geonets?

Create void space for in-plane flow Signup and view all the answers

What is a characteristic handling requirement for membranes?

Careful handling during installation Signup and view all the answers

Which application is NOT appropriate for the use of membranes?

Ground stabilization Signup and view all the answers

Which statement about geonets is incorrect?

They are primarily used for silt fence applications. Signup and view all the answers

Which type of geosynthetic material is known for being impermeable?

Geomembranes Signup and view all the answers

What is a unique feature of geocomposites compared to other geosynthetic materials?

They include a prefabricated core bonded to a geotextile filter. Signup and view all the answers

What is the primary purpose of geocells as originally developed?

To stabilize soft subgrades for large equipment mobilization Signup and view all the answers

Which of the following describes the material typically used for temporary erosion protection?

Open mesh polymeric and biodegradable mesh systems Signup and view all the answers

Why is termite resistant sand considered more beneficial than chemical barriers?

It requires less maintenance and is environmentally friendly Signup and view all the answers

In high-risk termite environments, what construction method is sometimes used to protect homes?

Designing homes on high concrete pillars Signup and view all the answers

What is the function of open mesh systems in erosion protection?

To anchor seeds and soil particles against erosive flow Signup and view all the answers

How do geocell systems arrive at the site?

Collapsed for delivery and then opened on site Signup and view all the answers

What is a key feature of termite mesh?

It is fine enough to prevent even tiny termites from passing Signup and view all the answers

What characteristic of geocell systems contributes to their ability to stabilize steep slope surfaces?

Their three-dimensional structure and filling Signup and view all the answers

Which material is commonly combined with polymeric systems for temporary erosion protection?

Biodegradable materials like jute Signup and view all the answers

What dimension range is common for geocell systems?

100mm to 200mm Signup and view all the answers

Study Notes

Acronyms

AASHTO: American Association of State Highway and Transportation Officials
ANSI: American National Standards Institute
ASTM: American Society for Testing and Materials
USCS: Unified Soil Classificatory System

AASHTO Soil Classification System

Classifies inorganic soils based on drainage and bearing capacity.
Particle sizes:
- Boulders: above 75mm
- Gravel: 75mm to No. 10 sieve
- Coarse Sand: No. 10 to No. 40 sieve
- Fine Sand: No. 40 to No. 200 sieve
- Silt-Clay Particles: passing No. 200 sieve

Atterberg Limits

Tests performed on soils passing the No. 40 sieve.
- Liquid Limit (LL): moisture content at which soil transitions from liquid to plastic state.
- Plastic Limit (PL): water content at which silt or clay crumbles when rolled into a 3.2 mm diameter tread.
- Plastic Index (PI): range of water content where sediment behaves plastically (LL - PL).

Fill Materials

Soil, crushed stone, and sand used to raise existing grades.
Classified under the USCS:
- GW, GM, GP: Gravels with > 50% retained on No. 200 sieve and 50% of coarse fraction retained on No. 40 sieve
- SW, SM: Sands with 50% retained on No. 200 sieve and 50% or more of coarse fraction passing No. 40 sieve

No. 40 Sieve

Granular Fill or Filters: soil materials conforming to General Fill requirements, ASTM C33, size 67, with a sand equivalent of not less than 50%.
Borrow Fill: soil suitable as fill or sub-grade, selected laboratory-approved pit-run gravel, disintegrated granite, sand, shale, cinders, with not more than 35% fraction passing the No. 200 sieve.
Base Course Materials: hard durable fragments of stone and a filler of sand, free from vegetable matter and clay, complying with AASHTO METHOD T-11 and T-26 Grading Requirements.

Riprap

Constructed layer of stone used to prevent erosion, scouring, or sloughing.
Ranges in diameter from 50 mm (2 inches) to 1148 mm (42 inches).

Gabion Systems

Stone-filled wire baskets used for soil stabilization and erosion prevention.
Wire fabric containers, uniformly partitioned, of variable size, interconnected with baskets.

Geosynthetics

Synthetic components made for use with or within earth materials.
Categorized into:
- Geotextiles: woven or nonwoven fabric made from polymeric materials.
- Geonets: continuous extrusion of polymeric ribs creating void space for in-plane flow.
- Geomembranes: continuous, impermeable polymeric sheets.
- Geocells: three-dimensional prefabricated polymeric systems ranging from 100mm to 200mm high.
- Geocomposites: combination of geosynthetic components.

Geotextiles

Most common geosynthetic.
General uses:
- Reinforcement: increases design strength and reduces sub-base and base course deterioration.
- Separation: prevents migration of dissimilar materials.
- Filtration: prevents movement of fine particles from the soil through seepage.

Filtration Categories

Subsurface Drainage: employed in subsurface drainage applications, such as filters around underdrains or edge drains.

Erosion Control

Employed to protect cut slopes or drainage features.
Serve a secondary function of separation when used with stone lining or rip rap.

Sediment Control Geotextiles

Exclusively used for silt fence applications.
Serve as filters with a different mechanism than subsurface drainage or erosion control.

Membranes

Ethylene propylene diene monomer (EPDM) is commonly used for membrane roofing.
Uses include lining for ponds, lagoons, landfills, canals, reservoirs, roads, and waterproofing.

Geocomposites

Usually a sheet or edge drain with a prefabricated core bonded to a geotextile filter.
The core provides void space for water flow.

Geomembranes

Continuous, impermeable polymeric sheets.
Manufactured from high-density polyethylene (HDPE) and polyvinyl chloride (PVC).

Geonets

Continuous extrusion of polymeric ribs creating void space for in-plane flow.
Available with or without bonded geotextile filters.

Geocells

Three-dimensional, prefabricated polymeric systems ranging from 100mm to 200mm high.
Used for stabilization and protection of steep slope surfaces and channel linings.

Slope-Erosion Protection Materials

Used for temporary and permanent erosion protection.
Temporary materials:
- Open mesh polymeric systems.
- Biodegradable mesh system (e.g., coco coir, jute).
- Combination of polymeric and biodegradable mesh.

Physical Barriers

Termite Resistant Sand

Layer of sand preventing termites from moving through or building tunnels.
More uniform and effective than chemical barriers.

Termite Mesh

Fine steel mesh that prevents termites from passing through.
Used in slab construction, wrapping pipes, and other access areas.

Home Construction

Homes are sometimes designed on high concrete pillars in high-risk areas to separate the home from termites.

Chemical Barriers

Objective: Create a continuous barrier between soil and structure to control termites.
Pre-construction barriers: Applied during construction to soil and foundations, or use of termite-resistant building products.
Vertical barriers: Rodding or trenching around foundation bases, plumbing, utility entrances, and expansion joints.
Horizontal barriers: Applying 1 gallon of termiticide per 10 square feet, typically by coarse spray at low pressure.

Slab Treatment

Drilling through slab floor and injecting termiticides into the soil at regular intervals.

Basements and Crawl Spaces

Trenches dug around foundation, with termiticide applied to trenches and soil within the crawl space/basement.

Colony Elimination (Bait) System

Objective: Eliminate entire worker population and colony using slow-acting insect growth regulator (IGR) - hexaflumuron - in baits.

Pavements

Wearing surface for pedestrian and vehicular traffic.
Thickness and construction factors:
- Intensity and type of traffic loads.
- Bearing capacity and permeability of the sub-grade.

Pavement Types

Rigid: Reinforced concrete slabs or paving units mortared over a concrete slab. Loads are distributed internally.
Flexible: Made of concrete, brick, or stone; flexes under pressure rather than cracking.

Turf Pavements

Unit pavers with spacing for grass or ground covers over a topsoil mix.
Used for driveways, patios, sidewalks, porch floors, etc.

Paving Patterns

Variety of shapes creating different patterns.
Absorb heating and movement.

Roads and Parking

Materials for horizontal structures.

Subgrade and Base Course Materials

Subgrade

Borrow Material: soil suitable as fill or sub-grade
Base Course Material: hard durable fragments of stone and a filler of sand

Choker Aggregate

A filter layer of finer material over a coarse road base material, providing a stable foundation for pavement.

Pervious Asphalt Pavement

Choker Course, uniformly graded clean crushed stone, 40% Voids

Surface Paving Material

Concrete

Described in a separate Module.

Bituminous Surfacing

HOT MIX ASPHALT or ASPHALTIC CONCRETE: dark brown to black cementitious material composed of bitumens.
COLD MIX ASPHALT OR ASPHALTIC CONCRETE: asphaltic concrete prepared with a relatively light and slow-curing asphalt, placed over a prepared surface without heat.
ASPHALTIC MACADAM: formed by grading and compacting layers of crushed-stone or gravel, then binding the top layer with asphalt.
ASPHALT OVERLAY: one or more courses of asphalt placed on existing pavement.
MACADAM ROAD: type of road construction using single sized aggregate layers of stone with a coating of binder.

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Description

Module 1 - Materials of Construction - Building Technology (Atlas)