Material & Methods Notes

6/30 - This will eventually be a list of notes for all subjects in this test subject starting with the sequence in the order of the Kaplan Study Material and Miscellaneous items to follow.

Lesson 1 - Site Work (ref: CSI Division 1)

Site Selection Factors (Controllable)

1. Meets program requirements (aka client needs)
2. Size
3. topography: Land forms & slopes of the ground (grading) - effects foundation, drainage and microclimate.
4. orientation: sun (solar radiation), wind(natural ventilation), views, ease of access. Prevailing exterior sounds effect orientation of building, material choice and sound control methods used.
5. Vegetation: effects microclimate, views, solar radiation, sound travel.
6. access: ease or difficulty getting to and accessing structures
7. utility availability: determine what services are available (water, electricity, gas, sewer, storm water, garbage)
8. regulations / restrictions: city, state and federal (ie. zoning, easements, subsurface rights, etc.)
9. Soil Composition: most importantly, bearing capacity of the soil. See SOIL section below.

Site Selection Factors (Un-controllable)

1. Geographic location: often controlled by the client
2. Climate
3. Sun
4. wind
5. precipitation

SOIL

Soil Composition

1. composition determines a soils bearing capacity
2. Soil: formed by chemical decomposition of rock; water, air and temerature action on rock; and the decay of vegetable and animal matter (organic material)
3. Makes up the top layer of the earth's surface.
4. Types are essentially similar throughout the world.
5. Classification Types:
6. Rock / Bedrock: solid, strongest support for foundation. Slate and shale are fine textured soft rock. Boulders are rock detached from the bedrock. Decomposed rock is disintegrated rock mass (ie. decomposed granite)
7. Hardpan: consolidated mixture of gravel, clay and sand. Good base for foundations.
8. Gravel: granular rock particles ranging in size from 1/4" to 3-1/2". Larger rock peices are called cobblestones, still larger = boulders.
9. Sand: loose granular rock particles about .002" to 1/4" in size. Not plastic or cohesive. Sand and Gravel provide excellent base for foundations. Also have excellent drainage properties with good permeability.
10. Silt: fin grained sediment deposited from running water. is .002" or less in size. Mixed with water it forms soft, plastic, stick material known as mud.
11. Clay: Fine grained, firm cohesive material. formed from decomposition and hydration of certain rock. Plastic when wet, hard when dry. Relatively imperveous. Swells when it absorbs water, shrinks when it dries, least stable and predictable soil. Can proivide satisfactory support for foundations based on carful investigation. Also used by firing to make brick, pottery and tile.
12. Quicksand: mixture of sand and moving water. completely unsuitable and a danger.

Soil is classified by the US Dept. of Agriculture as the following

1. Class 1 = Gravel
2. Class 2 = Sand
3. Class 3 = Clay
4. Class 4 = loam
5. Class 5 = loam with some sand
6. Class 6 = silt-loam and clay-loam
7. Class 7 = clay-loam

Allowable soil pressures = Table of allowable is contained in Uniform Building Code

Soil exploration and Testing (to determine soil composition)

1. Architect requests a subsurface exploration of the site.
2. Geotechnical engineer executes sample extraction and testing. Publish report of findings and suggestions for sub-soil, grading and foundation methods.
3. note: contracted to client, not liability or consultant of architect.

Testing Methods (type used depends on location, topography, depth of water table and structural load anticipated)

1. Test Pits: excavation which permits direct visual inspection. close-up of layers, access to undisturbed samples for laboratory testing. Costly. generally not dug below water table.
2. Soil Load Tests: loading platform erected on the site, incremental loads are applied, each load increment maintained until settlement becomes negligible for period of several hours. Test continues until settlement meadured becomes regular for each new loading. Total test load is usually double the contemplated design load.
3. Auger borings: extract soil samples via 2" or 2-1/2" auger fastened to a long pipe or rod. Stops at first obstruction (rock, hardpan or tree stump). Effective for sand or clay. Depths not exceeding 50'.
4. Wash borings: good for locating bedrock. For soil too compact for auger boring. Uses 2" to 4" auger driven into soil and contains a small jet pipe which water is forced through. material washes up thouroughly mixed which reduces dependability of samples. problem = boulders may be mistaken for bedrock. Can penetrate all materials. Can extend 100' or more.
5. Core borings: Brings up complete cores of material through which it passes. more costly and most reliable. penetrates all materials. Uses diamond drill, can cut through rock. Results are recorded in a test boring log book. Extends to great depths.
6. Dry sample borings: Uses a drive pipe with a split sampling pipe at the tip instead of a drill. Driven down and every 5 inches the sample is lifted and the sample is removed and stored. testing takes place in laboratory.
7. Notes: test in sufficient locations at each site over building area.

Soil properties (what samples are tested for)

1. Specific Gravity: determines void ratio (ratio of the volume of void spaces to the volume of solid particles in a soil mass.)
2. Grain Size (granular soils): estimates permeability, frost action, compaction and shear strength.
3. Grain shape: estimates shear strength (the property of a soil that enables its particles to resist displacement with respect to one another when an external force is applied.)
4. Liquid and Plastic limits (cohesive soils (soil that has considerable strength when unconfined and air-dried, and significant cohesion when submerged.)): to obtain compressibility and compaction values.
5. Water content (cohesive soils): to obtain compressibility and compaction values.
6. Void Ratio: to determine compressibility
7. Unconfined compression(cohesive soils): to estimate shear strength
8. notes: Geotechnical engineer publishes a written soil report of findings and recommends type of foundation to use and the allowable soil bearing pressure.

Soil and Site Problems

1. Inadequate bearing capacity.
2. Subsurface water
3. Shrinkage
4. Slippage
5. Seismic forces (some areas)
6. Settlement: deadload added to structure, soil beneath footings compresses reducing void volume and causes settlement. Slight amount of uniform settlement is of little concern. Eneven or differential settlement may cause SERIOUS cracks or failure. During construction constant checking should be made with surveying instruments to note of any settlement. Settlement may continue for number of years due to extended soil consolidation, moisture content changes or movement of earth itself.
7. Frost Action: cold climate freezing and thawing of soil. may cause ground to heave which stresses building foundations leading to serious damage. Depends on soil type and geographic location. Footings should be placed at least one foot below frost line (depth below which soild does NOT freeze).
8. Earth Movement: Prevalent with clay soils that swell when wet and shrink when drying. Considerable movement near surface. about five feet movement will be slight. Adjacent excavation could affect the clay. Sloped layers of earth can cause problems.

SOIL DRAINAGE

1. Moisture is a problem at and below grade. can reduce the soils load bearing capacity. leaking water into building.
2. Solutions: 1. location of subsurface water 2. Control of surface water.
3. Water Table: level below which all soil is saturated with ground water. foundations should be located well above the water table to avoid hydrostatic pressure damage.
4. Divert water away from foundation with drain tile system. At least six inches below lowest floor slab. Gravel over filter fabric and perforated piping.
5. Gravel fill below slabs not subject to hydrostatic pressure prevents water being drawn into slab via capillary action.
6. Continuous preformed waterstop between concrete cold joints poured separately (ie. floor slab and wall footing intersection)
7. Drainage of surface water: directing all surface water away from structures. shaping contours (grading) to provide gradual transition from high to low elevations, gutters, flumes, berms and gentle warp of paved surfaces collect and conduct water to yard drains, catch basins and underground storm drainage lines.

SOIL MODIFICATION: Soil can be altered in a variety of ways in order to improve its consistency, dependability and bearing capacity.

1. Alternate to soil modification, a. increase footing depth and area increases bearing capacity. b. Dranage improves physical charactaristics of soil, expecially where soil is affected by subterranean water flow.
2. Unusually soft Subsoil or containing organic fill = remove undesirable material and replace with compacted granular materials(costly). Also can cover with layer of sand, gravel or crushed rock and blend materials together producing an artificial hardpan material.
3. soil improvement = reduction of void volume.
4. Compaction by heavy machinery (sheepsfoot roller, think steam roller with knobbies all over, they look like sheep feet.)
5. Overcompaction can be an issue.

SITE PREPARATION

1. Demo existing structures
2. Remove and cap existing utilities.
3. Plants / Trees to remain must be protected
4. Vegetation to be removed, tree roots completely removed or grubbed, over time the roots will rot and leave an undesirable void.
5. Batter boards are used to locate building corners which are offset from the building line/edge with string line tied off to strike building edges. this makes room for excavation without knocking over the stakes.
6. Before grading, top six inches of soil (topsoil) is removed and stored on site for use at end of project to spread over area of final landscaping which forms the finish grade. On occasion, soil not worth saving and good top soil will have to be imported.

EARTHWORK: Consists of all grading work, excavation, rough grading and finish grading.

1. Excavation: removal of existing soil for construction of foundation and substructure.
2. Permanent CUT slopes max 1-1/2 to 1 slope.
3. Permanent FILL slopes max 2 to 1 slope. (could be an exception in geotech report)
4. Cubic yard of earth weighs more than a ton = unstable slopes pose a serious danger.

1. Grading: alteration of a site's contours, usually by power equipment.
2. Rough grading: additional removal of earth prior to start of construction.
3. Finish grading: final distribution of earth at conclusion fo construction. Accurate within one inch.

1. Backfill: earth replaced around a foundation or retaining wall after concrete forms are removed.
2. should be deposited in 6 to 12 inch layers and fully tamped and compacted to avoid settlement.

FOUNDATIONS: Part of building structure that transmits the building loads to the soil.

1. Footings: parts of the foundation system that are widened to spread the load over a large area of soil.
2. Building load must not exceed safe bearing capacity of underlying soil. Avoid settlement cracks, uneven structural movement or even failure of structure.

SHALLOW FOUNDATIONS

1. Requires soil close close to ground to be of adequate strength.
2. Most economical foundation system consisting of shallow spread footings.
3. Column footing = square or rectangular pad
4. Wall footing = continuous spread footing under a wall
5. Combined or cantilever footing = connects the exterior column footing with the first interior column footing.
6. Mat footing = one large footing under entire building area (distributes load)
7. raft foundation = for poor soil conditions
8. Boat footing = similar to mat footing, except it is placed deeper so that weight of soil removed for excavation is equal to the load of the building. (displacement) causing little or no new load to underlying soil.

DEEP FOUNDATIONS: Piles which are required when upper soil has insufficient bearing capacity to support spread footings.

1. Pile: A long slender column of wood, steel, reinforced concrete or a composite, pre-drilled, driven or hammered vertically into the earth to form part of a foundation system.
2. Transfer of load by skin friction between pile
3. and surrounding soil or end bearing which is supported by rock or firm subsoil under the pile tip.
4. Type of pile depends on size of load and presence of moisture with potential for deterioration. Concrete piles are generally most suitable and more permanent.
5. Driven piles are driven by steam air or diesel hammers that drop from one to four feet.
6. Water jetting piles is an option but not recommended due to ease of overexcavation.
7. Safe carrying capacity is determined by: pile-driving formulas, static pile formulas or static pile load tests which are most dependable.
8. Drilled piles are drilled then filled with concrete, common load transfer is skin friction. If transfered by end bearing then it's called a drilled caisson. bottom of shaft can be enlarged or belled.
9. Drilled piles / Caissons sometimes require a steel casing which is removed as concrete is poured.
10. Also called Caissons are box-like structures used where very wet or soft (or in water) soils are encountered. Ability construct below water level. Sides are of steel sheet piling, timber or concrete. Excavation is performed within caisson.
11. For bridge piers or sim located in water, entire area is water tight, water pumped out and then foundations are constructed = known as cofferdam.

Types of Piles:

1. Wood: Must be below permanent ground water level
2. Precast concrete: Round, square or octagonal, often prestressed
3. Cast-in-place concrete: Driven with mandrel core(heavy tube steel that's inserted into a thin walled casing to prevent from collapsing, removed before pouring), removed before pouring
4. Concrete filled steel pipe: Driven with sealed tip, then filled with conrete.
5. Structural steel: For dense earth and heavy loads - H section (W steel)
6. Seet piling: May be used as water dam (cassions and cofferdam construction)

TEMPORARY SUPPORTS

1. for temp support of excavated earth or existing structures.
2. Sheeting: temporary wall of wood, steel or precast conc. to retain soil around an excavation.
3. Slurry wall: type of sheeting, narrow trench filled with a slurry mixture of bentonite clay and water, (temporarily shores earth) rebar is dropped down, concrete is placed by tremie which displaces the slurry. tremie = a funnel like device with a pipe or tube for depositing concrete underwater.
4. Bracing is used to brace the sheeting to resist soil pressure. diagonal bracase aka rakers.
5. in lieu of rakers which interfere with construction clearances, tie-backs are used into surrounding soil.
6. Tie-back = Steel rod or tendon attached to a deadman or a rock or soil anchor to prevent lateral movement of a retaining wall or formwork.
7. Underpinning = Used to support existing foundations or walls being extended downward (excavated beneath). Two common methods are needle beams or pipe cylinders with hydraulic jacks.
8. Needle beam = a short beam passed through a wall as a temporary support while the foundation or part beneath is repaired, altered or strengthened.

SITE IMPROVEMENTS: not part of the strucure, ie. roads, walks, fences, walls, lighting and other landscape features.

1. Asphalt paving: derived from asphalt petroleum, applied either hot or cold in a single layer over a prepared foundation sub-base of course crushed stone or gravel covered by a base of course finer aggregate (sand).
2. Asphaltic concrete: Asphalt cement and graded aggregates proportioned and mixed in a plat, brought to site, spread over foundation and rolled while still hot.
3. Cold laid asphalt: same as asphaltic except cold liquid and aggregates are used.
4. Asphalt macadam: begins with base of crushed stone, gravel or slab compacted to a smooth surface, then sprayed with asphalt emulsion or hot asphalt cement in controlled quantities, coverd with fine aggregate and finally rolled until smaller aggregate fills the voids in the course aggregate.

OTHER PAVING MATERIALS

1. Brick paving: popular and durable, laid over bed of sand or cement/sand. more permanent laid over concrete slab foundation. May be slippery when wet, provide proper drainage.
2. Stone cobbles: mainly decorative, best = rounded river stones 2" to 4" in diameter, closely set in cement mortar.
3. Granite Setts: small, rectangular or square blocks of granite, set in cment mortar. very durable paved surface. high cost.
4. Flagstones: thin slabs of slate, bluestone or soapstone. various textures and colors. installed over sand bed or with mortar on concrete slab.

GRADE CHANGING DEVICES

1. Concrete or masonry retaining wall.
2. Concretee or stone battered wall
3. Cribbing
4. Stone riprap
5. Stepped living wall

(END SECTION)