CONSTRUCTION Flashcards
- Find the swell of a soil that weighs 2800
lb/cu yd (1661 kg/m3) in its natural state and 2000 lb/cu yd (1186 kg/m3) after excavation.
40%
Find the shrinkage of a soil that weighs 2800 lb/cu yd (1661 kg/m3) in its natural state and 3500 lb/cu yd (2077 kg/m3) after compaction.
20%
A soil weighs 1960 lb/LCY (1163 kg/LCM), 2800 lb/BCY (1661 kg/BCM), and 3500 lb/CCY (2077 kg/CCM). (a) Find the load factor and shrinkage factor for the soil. (b) How many bank cubic yards (BCY) or meters (BCM) and compacted cubic yards (CCY) or meters (CCM) are contained in 1 million loose cubic yards (593,300 LCM) of this soil?
(a) Load Factor = 0.70, Shrinkage
Factor = 0.80 (b) Bank Volume = 700,000
BCY or 415,310 BCM, Compacted Volume =
560,000 BCY or 332,248 BCM
Find the base width and height of a triangular spoil bank containing 100 BCY (76.5 BCM) if the pile length is 30 ft (9.14 m), the soil’s angle of repose is 37°, and its swell is 25%.
B = 7.45 m, H = 2.80 m
Find the base diameter and height of a conical spoil pile that will contain 100 BCY (76.5 BCM) of excavation if the soil’s angle of repose is 32° and its swell is 12%
D = 10.16 m, H = 3.17 m
Estimate the volume of excavation required (bank measure) for the basement shown in Figure 3. Values shown at each corner are depths of excavation. All values are in feet (m).
146.6 BCM
Find the volume (bank measure) of
excavation required for a trench 3 ft (0.92 m) wide, 6 ft (1.83 m) deep, and 500 ft (152 m) long. Assume that the trench sides will be approximately vertical.
255 BCM
Find the volume of excavation required for the area shown in Figure 4. The figure at each grid intersection represents the depth of cut at that location. Depths in parentheses represent meters.
14,596 BCM
Estimate the actual bucket load
in bank cubic yards for a loader bucket whose heaped capacity is 5 cu yd (3.82 m3). The soil’s bucket fill factor is 0.90 and its load factor is
0.80.
2.75 BCM
Find the expected production in loose cubic yards (LCM) per hour of a small hydraulic excavator. Heaped bucket capacity is 3⁄4 cu yd (0.57 m3). The material is sand and gravel with a bucket fill factor of 0.95. Job efficiency is 50 min/h. Average depth of cut is 14 ft (4.3 m). Maximum depth of cut is 20 ft (6.1 m) and average swing is 90
113 LCM/h
Find the expected production in loose cubic yards (LCM) per hour of a 3-yd (2.3-m3) hydraulic shovel equipped with a front-dump
bucket. The material is common earth with a bucket fill factor of 1.0. The average angle of swing is 75° and job efficiency is 0.80.
290 LCM/h
Determine the expected dragline
production in loose cubic yards (LCM) per hour based on the following information: Dragline size = 2 cu yd (1.53 m3)
Swing angle = 120°
Average depth of cut = 7.9 ft (2.4 m)
Material = common earth
Job efficiency = 50 min/h
Soil swell op = 25%
165 LCM/h
Estimate the production in loose cubic yards per hour for a medium-weight clamshell excavating loose earth. Heaped bucket capacity is 1 cu yd (0.75 m3). The soil is common earth with a bucket fill factor of 0.95. Estimated cycle time is 40 s. Job efficiency is estimated at 50 min/h.
53 LCM/h
A wheel tractorscraper weighing 100 tons (91 t) is being operated on a haul road with a tire penetration of 2 in. (5 cm). What is the total resistance (lb and kg) and effective grade when the scraper is ascending a slope of 5%; the scraper is descending a slope of 5%
9,100 kg, 10%
A wheel tractor-scraper weighing 100 tons (91 t) is being operated on a haul road with a tire penetration of 2 in. (5 cm). What is the total resistance (lb and kg) and effective grade when the scraper is descending a slope of 5%?
0 kg, 0%
A crawler tractor weighing
80,000 lb (36 t) is towing a rubber-tired scraper weighing 100,000 lb (45.5 t) up a grade of 4%. What is the total resistance (lb and kg) of the combination if the rolling resistance factor is 100 lb/ton (50 kg/t)?
5,535 kg
A four-wheel-drive tractor weighs 44,000 lb (20,000 kg) and produces a maximum rimpull of 40,000 lb (18,160 kg) at sea level. The tractor is being operated at an altitude of
10,000 ft (3050 m) on wet earth. A pull of 22,000 lb (10,000 kg) is required to move the tractor and its load. Can the tractor perform under these conditions? Use Equation 8 to estimate altitude deration
No, because the maximum pull as
limited by traction is less than the required pull
Use the performance curve of Figure 1 to determine the maximum speed of the tractor when the required pull (total resistance) is 60,000 lb (27,240 kg).
2.4 km/h
Using the performance curve of Figure 2, determine the maximum speed of the vehicle if its gross weight is 150,000 lb (68,000 kg), the
total resistance is 10%, and the altitude derating factor is 25%.
10 km/h
A power-shift crawler tractor has a rated blade capacity of 10 LCY (7.65 LCM). The dozer is excavating loose common earth and pushing it a distance of 200 ft (61 m). Maximum reverse speed in third range is 5 mi/h (8 km/h). Estimate the production of the dozer if job efficiency is 50
min/h
271 LCM/h
Estimate the hourly production in loose volume (LCY and LCM) of a 31/2-yd (2.68-m3) wheel loader excavating sand and gravel (average material) from a pit and moving it to a stockpile. The average haul distance is 200 ft (61 m), the effective grade is 6%, the bucket fill factor is 1.00, and job efficiency is 50 min/h
168 Lm3/h (Actual Board: 178 Lm3/h)
Estimate the production of a single-engine two-axle tractor scraper whose travel-time curves are shown in Figures 4 and 5 based on the following information:
Maximum heaped volume = 31 LCY (24 LCM)
Maximum payload = 75,000 lb (34,020 kg)
Material: Sandy clay, 3200 lb/BCY (1898 kg/BCM), 2650 lb/LCY (1571 kg/LCM), rolling resistance 100 lb/ton (50kg/t)
Job efficiency = 50min/h
Operating conditions = average
Single pusher
Haul route:
Section 1. Level loading area
Section 2. Down a 4% grade, 2000 ft (610 m)
Section 3. Level dumping area
Section 4. Up a 4% grade, 2000 ft (610 m)
Section 5. Level turnaround, 600 ft (183 m)
192 BCM/h
The estimated cycle time for a wheel
scraper is 6.5 min. Calculate the number of pushers required to serve a fleet of nine scrapers using single pushers. Determine the result for both backtrack and chain-loading methods.
2 and 3
Find the expected production of the
scraper fleet of Example 10 if only one pusher is available and the chain-loading method is used. Expected production of a single scraper assuming adequate pusher support is 226 BCY/h (173 BCM/h)
1,112 BCM/h
Given the following information on a
shovel/truck operation, (a) calculate the number of trucks theoretically required and the production of this combination; (b) calculate the expected production if two trucks are removed from the fleet
(a) 11 trucks and 212 BCM/h
(b) 186 BCM/h
Fifteen miles (24.1 km) of gravel road require reshaping and leveling. You estimate that six passes of a motor grader will be required. Based on operator skill, machine characteristics, and job conditions, you estimate two passes at 4 mi/h (6.4 km/h), two passes at 5 mi/h (8.0 km/h), and two passes at 6 mi/h (9.7 km/h). If job efficiency is 0.80, how many grader hours will be required for this job?
23.1 h
Trial blasting indicates that a rectangular pattern of drilling using 3-in. (7.6-cm) holes spaced on 9-ft (2.75-m) centers and 20 ft (6.1 m) deep will produce a satisfactory rock break with a particular explosive loading. The effective hole depth resulting from the blast is 18 ft (5.5 m). Determine the rock volume produced per foot (meter) of drilling.
6.8 m3/m
Estimate the hourly production and the unit cost of the rock excavation involved in preparing an industrial building site by drilling and blasting. The site is 300 ft (91.4 m) by 400 ft (121.9 m) and must be excavated to an average depth of 12 ft (3.658 m). The material to be excavated is a thinly laminated shale with a sonic velocity of 4000 ft/s (1220 m/s). The drilling equipment to be used will consist of an air-powered track drill and air compressor. The average drilling rate, including steel changes, moves, and delays, is estimated at 100 ft/h (30.5 m/h).Trial blasting indicates that 3-in. (7.6-cm) holes drilled in a 12-ft (3.658-m) rectangular pattern will provide adequate fracturing. A hole depth of 13.5 ft (4.115 m) must be drilled to yield a 12-ft (3.658-m) effective depth. The blasting agent is ANFO. One-half pound (0.23 kg) of primer with an electric blasting cap will
be used in each hole. The powder factor is 0.5
lb/BCY (0.297 kg/BCM).
A labor force of one drill operator and one
compressor operator will be used for drilling. One blaster and one helper will be employed in blasting.
Cost information:
Labor: Blaster = $18.00/h Helper = $15.00/h
Drill operator = $17.50/h Compressor
operator = $18.00/h
Equipment: Track drill and compressor = $63.00/h Material: ANFO = $0.32/lb
($0.705/kg) Primer, cap, and stemming = $3.00/hole
362.3 BCM/h and $ 0.634/BCM
Estimate the hourly production and the unit cost of rock excavation by ripping for the problem of Example 28. Field tests indicate that a D7G dozer with ripper can obtain satisfactory rock fracturing to a depth of 27 in. (0.686 m) with two passes of a single ripper shank at 3-ft (0.914-m) intervals. Average speed, including turns, is estimated at 82 ft/min (25 m/min)
392 BCM/h and 0.242/BCM
A jaw crusher is producing 250 tons/h (227 t/h) of crushed gravel and discharging it onto a three-screen deck. The top screen in the deck is a 11⁄ 2 in. (38-mm) screen. The gradation of crusher output shows 100% passing 3 in. (76 mm), 92% passing 11⁄ 2 in.(38 mm), and 80% passing 3⁄ 2 in. (19 mm). Material weight is 115 lb/cu ft (1842 kg/m3). Find the minimum size of the 11⁄ 2 in. (38-mm) screen to be used. Check both total screen load and screen passing capacity
2.9 m2
Calculate the volume of plastic
concrete that will be produced by the mix design given in the table
0.51 m3
Determine the actual weight of each
component to be added if the sand contains 5% excess moisture and the gravel contains 2% excess moisture
Water = 63 kg, Sand = 447 kg, Gravel
= 560 kg
Determine the weight of each component required to make a three-bag mix and the mix volume.
Cement = 127.8 kg,
Sand = 370 kg,
Gravel = 464 kg,
Water = 52 kg,
Mix Vol. = 0.42 m3
Calculate the maximum hourly production of an asphalt plant based on the data in the following list.
Mix composition:
Asphalt = 6%
Aggregate composition:
Coarse A = 42%
Coarse B = 35%
Sand = 18%
Mineral filler = 5%
Aggregate moisture = 8%
Dryer capacity at 8% moisture removal = 110 ton/h
123 ton/h
Determine the rated size of air compressor required to operate the following tools at an altitude of 6000 ft (1830 m). Assume a 10% leakage loss and a job load factor of0.80
49.1 m3/min
The compressed air system illustrated in Figure 5 is being operated with a receiver pressure of 110 psig (758 kPa). Pressure drop in the manifold is determined to be 2 psig (13.8 kPa). If all three drills are operated simultaneously, what is the pressure at the tools? Assume no line leakage.
708.9 kPa (gauge)
Determine the safe load capacity of a 6-in.-square concrete pile 60 ft long. Assume that the unit weight of the pile is 150 lb/cu ft.
Pile driver energy = 14,000 gt-lb
Ram weight = 4000 lb
Weight of driving appurtenances = 1000 lb
Average penetration last six blows = 1/5 in./blow
59,862 lb
Calculate the safe load capacity of a bulb pile based on the following driving data. Hammer weight = 3 tonsHeight of drop = 20 ft
Volume in last batch driven = 5 cu ft
Number of blows to drive last batch = 40
Volume of base and plug = 25 cu ft
Selected K value = 25
164 tons
Design the formwork (Figure 2) for an
elevated concrete floor slab 6 in. (152 mm) thick. Sheathing will be nominal 1-in. (25-mm) lumber while 2 × 8 in. (50 × 200 mm) lumber will be used for joists. Stringers will be 4 × 8 in. (100 × 200 mm) lumber. Assume that all members are continuous over three or more spans. Commercial 4000-lb (17.8-kN) shores will be used. It is estimated that the weight of the formwork will be 5 lb/sq ft (0.24 kPa). The adjusted allowable stresses for the lumber being used are as follows:
6.22 kPa
Determine the maximum spacing of
nominal 2 × 4–in. (50 × 100–mm) lateral braces for the wall form of Example 2 placed as shown in Figure 4. Assume that local code wind requirements are less stringent than Table 3. Allowable stress values for the braces are as follows
3.31 m
Determine the design lateral
force for the slab form 6 in. (152 mm) thick, 20 ft (6.1 m) wide, and 100 ft (30.5 m) long shown in Figure 5. The slab is to be poured in one pour. Assume concrete density is 150
lb/cu ft (2403 kg/m3) and that the formwork weighs 15 lb/sq ft (0.72 kPa).
(APR 2023)
1.46 kN/m
Calculate the number of bricks 33⁄4 ×
21⁄4 × 8 in. (95 × 57 × 203 mm) laid in
running bond required for a double wythe wall 8-ft high by 14-ft wide (2.44 × 4.27 m) having one opening 48 × 72 in. (1.22 × 1.83 m) and one opening 32 × 48 in. (0.81 × 1.22 m). Mortar joints are 1⁄2 in. (13 mm). Allow 3% for brick waste
981
Estimate the quantity of mortar required for the problem of Example 1. The joint thickness between wythes is 1⁄2 in. (13 mm). Assume a 25% waste factor.
0.53 m3
Using the straight-line method of
depreciation, find the annual depreciation and book value at the end of each year for a track loader having an initial cost of $50,000, a salvage value of $5000, and an expected life of 5 years
$ 9,000
Estimate the hourly repair cost for the first year of operation of a crawler tractor costing $136,000 and having a 5-year life. Assume average operating conditions and 2000 h of operation during the year
$ 4.08
Calculate the expected hourly owning and operating cost for the second year of operation of the twin-engine scraper described below.
Cost delivered = $152,000
Estimated life = 5 years Tire cost = $12,000
Salvage value = $16,000
Depreciation method = sum-of-the-years’-digits
Investment (interest) rate = 10%
Tax, insurance, and storage rate = 8%
Operating conditions = average
Rated power = 465 hp
Fuel price = $1.30/gal
Operator’s wages = $32.00/h
$ 97.34/h
A copper wire has a nominal
breaking strength of 300 MPa and a reduction of area of 77 %. Calculate the true tensile strength.
(NOV 2022)
1,300 MP
A 2-in (5.08 cm) gage length is marked on a copper rod. The rod is strained so that the gage marks are 2.27 in. (5.77 cm). Calculate the strain.
13.5%
If the average modulus of elasticity of the steel used is 205,000 MPa, how much will a wire 2.5 mm in diameter and 3 meters long be formed when it supports a load of 500 kg?
1.5 cm
A copper wire has a nominal breaking strength of 300 MPa and a reduction of area of 77 %. Calculate the true strain at the point of fracture.
147%
An aluminum wire is stressed
34.5 MPa in tension. What temperature increase is required to change its length by the same amount?
. (NOV 2022)
22˚C
A stainless steel plate 0.4 cm thick has circulating hot water on one side and a rapid flow of air on the other side, so that the two metal surfaces are 90˚C and 20˚C, respectively.
How many joules are conducted through the plate per minute
1,575 J/cm2 min
The true density of a concrete
to which an air-entraining agent was added is 2.80 g/cm3. However, a dry core (15.24 cm × 10.16 cm in diameter) of this concrete weighs only 2.982 kg. The same core weighs 3.08 kg when saturated with water. What are the percents of the open and closed pores?
. (MAY 2022) T
7.9% and 5.9%
The true density of a concrete to which an air-entraining agent was added is 2.80 g/cm3. However, a dry core (15.24 cm × 10.16 cm in diameter) of this concrete weighs only 2.982 kg. The same core weighs 3.08 kg when saturated with water. What are the bulk and apparent densities?
2.41 and 2.62
A concrete unit mix contains
136 kg of gravel, 95 kg of sand, 42.5 kg of Portland cement, and 22.5 kg of water, plus 5% entrained air. How much cement is required to build a low retaining wall, 28.6 m by 1.07 m by 0.305 m? (The aggregate is non porous)
(NOV 2021)
: 71.5 unit mixes
An electrical porcelain has only 1%
porosity as sold. It had 27% porosity after pressing and drying, but before sintering. How much linear shrinkage occurred during sintering?
9.7%
To compress 2.8 m3 of free air per minute from atmospheric (0.101 N/mm2) to (0.7 N/mm2) indicated on the gauge (i.e. 8.01 bar absolute).
(NOV 2021)
9.7 kW or 13.1 HP
To compress 2.8 m3 of free air per minute from 0.05 N/mm2 (atmospheric pressure) to 0.801 N/mm2 (absolute pressure) requires a compressor with a power value of?
(APR 2023)
: 6.47 kW
Determine the hourly production of a 0.57 m3 capacity backhoe, excavating a foundation 3 m deep in common earth.
Ideal output = 100 m3/h
Backhoe proportion of face shovel proportion = 0.8
Swing factor = 1.0
Job Conditions = 40% loss
Swell Factor = 1.1
(APR 2023)
: 44 m3/h
Trucks are loaded by a 1 m3
capacity tracked loader machine at the rate of 30 m3/h bulked material. The truck transport the material to a tip 3 km away. Select the size and number of trucks required. Select truck size, say loader bucket capacity × 5 = 5 m3
Load time = 60/30 × 5 = 10 minutes
Cycle time to tip and back = 18minutes
Average Speed – 20 km/h
: Three 5 m3 capacitY
