CTC-275 Construction Methods Intro & Earthwork

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Many different ways to build same building How many ways can you build a ham and cheese sandwich? Types of ham, bread, cheese, toppings

Construction methods change when Materials change Why thatch roofs? Why teepees and long houses? How important where nails to building Equipment changes Horses to steam engines to today Erie Canal was dug with shovels and rock sleds Steam engines were stationary with belts going from pulleys to the engine

House Construction What materials can be used to build a house and what equipment is required Wood – hammers, saws, drills, squares Can also use engineered wood What has happened to lumber in last 100 years? Concrete – either cast in place, precast, or shotcrete Can be above ground or below Steel Stone Brick Adobe – only need forms Haybales

House Construction Wooden houses can be constructed using three methods 1. Balloon Framing 2. Platform Frame 3. Modular – assembly line

Questions What made skyscrapers possible? How old is concrete and who first used it How old are nails?

Construction Order There is an order to all projects What activities get done first What activities need to be done in a specific order What activities can be done at any point in time

Construction Order Above ground Swimming pools Remove topsoil & level area 3’ larger that pool diameter Rake soil to remove rocks and roots Layout bottom track Dump sand inside pool area Level track Layout wall parts Roll wall and put on J channel and top rail Bolt wall, attach skimmer

Construction Order Swimming pools Spread sand inside pool wall – rake & tamp Attach wall uprights Attach liner to J channel Use vacuum to suck liner to wall Plumb sand filter & pump together w/ skimmer & return line Attach top coping Add water Cut out skimmer and return

Construction Order Buildings: Clear site Foundation work Framing & Siding Roofing Windows and Doors Siding Electrical - rough Plumbing - rough Insulation Wall finishes

Construction Order Buildings: Foundation slab HVAC Ceilings Electrical – finish Plumbing – finish Paint/wall coverings Flooring Landscaping Pavement

Construction Order How far along do you need to be before starting next activity? On a house – probably one at a time On a 1 floor bldg – probably 1 activity at a time but depends on size Skyscraper – 1 activity per floor

Construction Order Highways Centerline survey Clearing Bridge work Earthwork to get to bottom of subbase elevation Subbase placement Base placement

Construction Order Highways Centerline survey Drainage Utilities (lights etc) Pavement base course Pavement wearing course Side slope grading Guard rail Lights and signs Pavement Markings

Construction Order Move from one end of project to the other with each activity Have multiple activities happening at any time Surveying is a full time activity

Start at beginning Earthwork Moving rock or soil from one location to another Processing it to meet location, elevation, density moisture content, etc Efficient earthwork requires: accurate estimating of work quantities and conditions, proper equipment, competent job mangement

Equip Selection Proper equipment has major impact on efficiency and profitablility Can equipment perform required work Also look at profitablility, other uses for equipment, return on investment, availability of parts and services, effect of downtime on other construction equip

Equipment planning Need to plan to effectively use equipment Production of equipment Production = Volume per cycle/cycles per hour Cycles per hour is based on efficiency of equip Swing angle and elevation to truck bed Soil hardness and Soil type Room to manuever

Equipment planning Cost per production unit = equip cost per working hour/equip production per hour Table 2-1 show efficiencies

Soil And Rock General Soil Characteristics Trafficability – ability of soil to support weight of vehicles under repeated traffic Controls traffic on unimproved access roads Also gives measure of how earthmoving equip will operate Primarily function of moisture conditions and soil type Loadability – how difficult to excavate and haul a soil Granular – high Compact cohesive - low

Soil And Rock Unit Soil Weight Pounds /cy Depends on soil type, moisture content, degree of compaction Relation between soil weight and bearing capacity So soil weight is used as a measure of compaction Soil weight is also a factor in hauling

Soil And Rock Moisture Content(%) = (moist wt – dry wt)/dry wt X 100 Soil sample 120# Dry weight 100# MC = (120-100)/100X100 = 20%

Soil ID Boulders Cobbles – over 3” diameter Gravel 1/4” – 3” diameter Sand 0.7mm (200 sieve) – ¼” diameter Silt 0.002 – 0.7 mm Clay less than 0.002mm Organic Matter decaying organic matter Soils classified using these types

Soil Classification Systems Unified System All material 3’’+ removed Separates soils into two main groups- Fine grained and coarse grained Table 2-2, Figure 2-1 AASHTO System 7 classes of soil Based on suitability of soil for subgrade Table 2-3 Table 2-4

Soil Volume Change Characteristics Soil Conditions Bank – material in natural state before disturbance – Bank cubic yard Loose – material that has been excavated or loaded loose cubic yard Compacted – material after compaction compacted cubic yard

Soil Volume Change Characteristics Swell Soil increases in volume when it is excavated Soil grains are loosened and air fills voids So 1 unit of soil in bank is smaller than the soil once it is excavated Swell(%) = ((weight/bank vol)/(weight/loose vol)-1)X100 Soil wt = 2800#/cy in bank Soil wt = 2000#/cy loose Swell = ((2800/2000)-1)X100 = 40%

Soil Volume Change Characteristics Shrinkage Soil decreases in volume when it is compacted Air is forced out of soil So 1 unit of soil compacted is smaller than the soil in the bank or once it is excavated Shrinkage(%) = (1-(weight/bank vol)/(weight/compacted vol))X100 Soil wt = 2800#/cy in bank Soil wt = 3500#/cy compacted Shrinkage = (1-(2800/3500))X100 = 20%

Soil Volume Change Characteristics Load and Shrinkage Factors Need a common unit of measure for earthwork (get rid of calculations ) Can use any of the three measures Called pay measure in contract Load factor = 1/(1+swell) How many BCY can fit on a truck LCY *Load Factor = BCY Shrinkage factor = 1- shrinkage How many BCY needed for CCY BCY * Shrinkage factor = CCY

Soil Volume Change Characteristics How many 10cy truck loads of soil = 1000CCY ? Swell = 30% Shrinkage = 25% BCY = CCY/(1-shrinkage) LCY = BCY*(1+Swell) LCY = CCY/(1-shrinkage)*(1+swell) LCY = 1000/(0.75)*1.30 = 1735 LCY Truck loads = LCY/10 = 174 truck loads

Spoil Banks Material removed from excavation Longer than wide – spoil bank – triangular x section Conical – spoil pile To determine the size of the bank or pile need swell and angle of repose for soil Angle of repose = angle that soil on side of bank naturally form Varies with moisture content and type Table 2-6

Spoil Banks Spoil bank Vol = X sect area x length B = (4V/(lx tan R))^1.2 H = (B x tan R)/2 B – base width H height L length R angle of repose V volume

Spoil Banks Spoil pile Vol = 1/3 p(D/2)^2 X H D = (7.64V/tan R)^1/3 H = D/2 x tan R D – diameter of base H height R angle of repose V volume

How long would a spoil bank for 40000 cy be if it was 100’ wide How long would a spoil bank for 40000 cy be if it was 100’ wide? Angle of repose = 30 deg How high can a spoil pile 50’ in diameter be if the angle of repose = 35 deg? How many cy can it hold?

Estimating earthwork 3 types of excavations Roadways Small pit Trench Large areas Roadways Find cut and fill using cross sections Mass diagram

Roadways

Estimating earthwork Pit Excavations Area X average depth Depending on size and ground may break into several geometric shapes to get volume Give bank volume

Estimating earthwork Trench Excavations V = x sectional area X length Take x sections every 50 feet and compute volumes between x sections When estimating don’t forget the angle of repose and OSHA

Estimating earthwork Large Areas Use a grid to find volume V = A*(average depth) For a rectangle V = (LxW)(h1+h2+h3+h4)/4(1/27) cy

Estimating earthwork