Greater Detail: STRUCTURES & MATERIALS Flashcards
The incorporation of tiny air bubbles into concrete to improve its workability, strength, and resistance to frost
Air Entertainment
Lightweight, corrosion resistant metal with high conductivity but no magnetic properties
Aluminum
Thin bituminous liquid asphalt applied between pavement lifts to promote boding
asphalt-to-asphalt
asphalt-to-concrete
Tack Coat
Benefits of steel reinforcement in concrete
- Absorb tensile, shear, and sometimes compressive stresses
- Ties horizontal and vertical elements
- Reinforces edges around openings
- Controls thermal expansion and contraction
Best curing temperature for concrete
50 - 85 degrees Fahrenheit
A unit of measurement for lumber that equal 1” x 12” x 12”
A board foot
2 primary issues for retaining walls related to drainage:
- Water pressure (groundwater) causes a wall to overturn
2. Saturation of soil (surface runoff) reduces the soil’s bearing capacity causing a wall to overturn
Method of addressing water pressure in retaining wall design / detailing
Weep holes near base of the wall
Lateral drain pipe installed behind wall to collect and dispose of excess groundwater
Method of addressing soil saturation in retaining wall design / detailing
Redirecting stormwater (e.g. Swales / drains uphill of the wall)
Curb types (3):
- Batter-faced (most common)
- Beveled (mountable)
- Rounded (mountable)
Soil conditions for shallow footings
Firm soil / light structure
Soil conditions for deep footings
Weak surface soils with stable underlying soils / bedrock
Made of steel or concrete; driven into soil bedrock or soil with sufficient bearing capacity to carry the structural load is met
Piles
Similar to piles but constructed by drilling holes and filling with concrete
Caissons
A classification system that groups soils based on their suitability for roadway subgrades
AASHTO
American Association of State Highway Transportation Officials
Textural classification based on 3 major particle size groups: sand, silt, clay
First developed for agricultural purposes
USDA Textural Classification System
soil triangle
Stability of structures / footings will depend on (2) :
- Soil type
2. presence of groundwater / pore water pressure
Compaction requirements of fill and the need for sheeting / shoring are dictated by
Soil type
Sandy non-cohesive soils (3 features)
More erodible
More permeable
Easy to drain
Clayey soils (3 features)
More erosion resistant
Less permeable
More difficult to drain
Engineering Properties of Soils
Properties that relate to a soil’s suitability as a construction material
Determined by the soil’s mineralogy, composition, structure, and moisture = these characteristics together influence the soil’s strength, permeability, and compressibility
Soils that addresses load-beading requirements while providing adequate space for root growth :
Stone that may be compacted to desired loading requirements but that maintains adequate pore space for root growth
Structural Soils
Geotextile Type that conveys water within the plane of the fabric (e.g. to remove excess water)
Drainage
Geotextile type that allows movement through plane of fabric while preventing movement of soil particles
Filtration
Geotextile type that distributes loads to the underlying soil (e.g. where soft foundation soils are present)
Reinforcement
Geotextile type that prevents the mixing of two different materials during installation or where mixing would be detrimental (over a gravel base for concrete)
Separation
Geotextile type that prevents the mixing of two different materials during installation or where mixing would be detrimental (over a gravel base for concrete)
Separation
Densification of soil by decreasing voids; increasing density of a soil increases its bearing capacity and shear strength
Compaction
Note: increasing moisture content decreases the degree to which soils may be compacted (void spaces are filled w/ water)
Standard Proctor Test and Modified Proctor Test
Used to determine soil density
Green Roof components (in order from roof deck up) (9)
- Waterproofing membrane
- Root Barrier
- Protection Board
- Insulation
- Drainage and retention layer
- Filter Fabric
- Growing Medium
- Planting
- Mulch
____ Green Roof
2-6” lightweight growing medium w/ drought tolerant species
Typically not irrigated
Extensive
Typical LBS/SF weight of an extensive green roof
15-30 lbs / sf
Protects roof deck from water infiltration
Green roof component
Waterproofing membrane
Protects the waterproofing membrane and roof deck from roots
(Green roof component)
Root barrier
may not be needed if the membrane does not contain organic materials that would attract root growth
Protects waterproofing membrane and root barrier from damage during construction
(Green roof component)
Protection Board
Protects from winter heat loss
May be used to build up topo / reduce soil depths needed
(Green roof component)
Insulation
Provides aeration to growing medium and prevents over-saturation
Drainage and retention layer
Used to separate the drainage layer from the growing medium
Green roof component
Filter fabric
Lightweight mineral base w/ small amount of organic matter. Does not contain silt, which will clog filter fabric
(Green roof component)
Growing medium
Green roof mulch types
Wood chip
Straw (good for windy conditions)
Stone aggregate (good for windy conditions if substantial)
Lives loads are specified in what units?
PSF
source: LARE app
The actual size of a 4x8 is?
- 5x7.25”
source: LARE app
Does green or seasoned wood have greater nail strength
Seasoned
source: LARE app
4x4 posts are suitable for what height range
6-8 ft
source: LARE app
4x6 posts are suitable for up to what max height
10 ft
source: LARE app
What shape will an asphalt road create typically
Parabola
source: LARE app
What shape will a concrete road create typically
Chevron
source: LARE app
Composition of mortar
Cement, sand, water, lime
Used to bond precast masonry units
(source: LARE app)
A hydraulic cement made by burning a mixture of clay and limestone in a rotary kiln and pulverizing the resulting clinker into a very fine powder
Portland Cement
source: LARE app
A cement with moderate sulfate resistance. Has low C3A content (<8%).
Used for structures exposed to soil or water containing sulfate ions.
Type II Cement
source: LARE app
General purpose cement. Has high C3S content for good early strength development.
Used for general construction (most buildings, bridges, pavements, precast units, etc)
Type I Cement
source: LARE app
Typical gap of deck boards
3/16”
Equipment used to compact soil depends on :
Soil Type
Sandy soils : vibratory steel drum (helps to shake and rearrange particles to reduce void space)
Fine sands and nonplastic silts : heavy rubber-tired rollers
Clayey soils : kneading using sheepsfoot roller
Retaining wall batter minimum ratio
12 to 1
