Practice Problems: Construction Methods
Question 1
A construction manager is planning the excavation for a basement foundation. The excavation is rectangular, measuring 60 ft × 40 ft, with a depth of 12 ft. The soil has a swell factor of 25% and a shrinkage factor of 10%. If the excavated material will be hauled away, what volume of soil must be transported in its loose state?
(a) 28,800 ft³
(b) 36,000 ft³
(c) 32,400 ft³
(d) 25,920 ft³
Question 2
A project engineer is estimating the number of truck loads required to remove excavated material. The bank volume of soil to be excavated is 5,000 yd³. The soil has a swell of 20%. Each truck has a capacity of 15 yd³ (loose measure). How many truck loads are required?
(a) 334 loads
(b) 400 loads
(c) 333 loads
(d) 417 loads
Question 3
A contractor is scheduling concrete placement for a large mat foundation. The foundation measures 80 ft × 60 ft × 4 ft thick. The concrete supplier can deliver concrete at a rate of 120 yd³/hr. The contractor wants to complete the pour in one continuous operation with a safety factor of 1.5 hours added to the calculated time. What is the minimum scheduled duration for the concrete delivery?
(a) 9.5 hours
(b) 10.4 hours
(c) 8.9 hours
(d) 11.9 hours
Question 4
A site supervisor is planning formwork removal for concrete columns. The columns were poured 48 hours ago using Type I Portland cement. The average ambient temperature has been 75°F. According to ACI 347, what minimum compressive strength must the concrete achieve before the column forms can be safely removed if the forms are non-load-bearing?
(a) 1,500 psi
(b) 2,500 psi
(c) 3,000 psi
(d) 500 psi
Question 5
A construction engineer is evaluating a crane lift for a precast concrete panel weighing 18,000 lb. The panel will be lifted at a radius of 45 ft from the crane's centerline. The crane's load chart indicates a capacity of 22,000 lb at 40 ft radius and 19,000 lb at 50 ft radius. Using linear interpolation and applying a safety factor of 0.85 to the crane capacity, is the lift within safe operating limits?
(a) Yes, safe capacity is 18,275 lb
(b) No, safe capacity is 17,425 lb
(c) Yes, safe capacity is 19,100 lb
(d) No, safe capacity is 17,850 lb
Question 6
A geotechnical engineer specifies that a granular base course must be compacted to 95% of maximum dry density. Laboratory testing indicates the maximum dry density is 128 pcf at optimum moisture content of 8.5%. A field test on a compacted section yields a wet density of 131 pcf at a moisture content of 9.2%. What is the percent compaction achieved in the field?
(a) 95.3%
(b) 93.2%
(c) 96.8%
(d) 91.7%
Question 7
A contractor is using the Critical Path Method (CPM) to schedule a project. Activity D has a duration of 8 days, earliest start (ES) of day 12, and earliest finish (EF) of day 20. The latest finish (LF) is day 25. What is the total float for Activity D?
(a) 3 days
(b) 5 days
(c) 7 days
(d) 13 days
Question 8
A demolition contractor is removing a reinforced concrete slab measuring 30 ft × 25 ft × 8 inches thick. The concrete weighs 150 pcf, and the reinforcing steel comprises approximately 2% of the total weight. If the debris will be loaded into dump trucks with a 12-ton capacity (using only 85% of capacity for safety), how many truck loads are required?
(a) 4 loads
(b) 5 loads
(c) 6 loads
(d) 7 loads
Question 9
A project manager is evaluating productivity for masonry work. A crew of 4 masons and 2 laborers laid 2,400 concrete blocks in an 8-hour shift. Each mason is paid $45/hr and each laborer $28/hr. What is the labor cost per block?
(a) $0.75
(b) $0.85
(c) $0.93
(d) $1.07
Question 10
An earthwork contractor is using scrapers to excavate and haul soil. The scraper has a heaped capacity of 22 yd³ (loose measure). The soil has a load factor of 0.90 due to soil type and conditions. The cycle time is 8 minutes, and the job efficiency is 50 minutes per hour. What is the estimated production in bank cubic yards per hour if the shrinkage factor is 10%?
(a) 110 BCY/hr
(b) 123 BCY/hr
(c) 99 BCY/hr
(d) 137 BCY/hr
Question 11
A construction superintendent is planning the placement of reinforcing steel for a suspended slab. The slab is 6 inches thick and requires #5 bars at 12 inches on center each way. The bars must have 2 inches of clear cover. What is the effective depth of the slab for structural calculations, measured from the top surface to the centroid of the bottom reinforcement?
(a) 3.69 inches
(b) 4.31 inches
(c) 3.94 inches
(d) 5.19 inches
Question 12
A general contractor is analyzing the dewatering requirements for a foundation excavation. The excavation is 40 ft × 30 ft × 15 ft deep in soil with a permeability of 0.003 ft/min. The groundwater table is 3 ft below the ground surface. Using Darcy's Law approximation with a hydraulic gradient of 0.5, what is the estimated inflow rate that the dewatering system must handle?
(a) 0.9 gpm
(b) 27 gpm
(c) 54 gpm
(d) 108 gpm
Question 13
A paving contractor is placing asphalt concrete for a parking lot. The area to be paved is 20,000 ft² with a compacted thickness of 3 inches. The asphalt mix has a compacted density of 145 pcf. If the delivery trucks carry 22 tons each, how many truckloads are required?
(a) 7 loads
(b) 8 loads
(c) 9 loads
(d) 10 loads
Question 14
A structural engineer is inspecting a concrete pour. Cylinder tests taken at 7 days show an average compressive strength of 2,800 psi. The specified 28-day strength is 4,000 psi. Assuming Type I cement and normal curing conditions, is the concrete on track to meet the specified strength using the typical relationship that 7-day strength is approximately 70% of 28-day strength?
(a) Yes, projected 28-day strength is 4,000 psi
(b) No, projected 28-day strength is 3,733 psi
(c) Yes, projected 28-day strength is 4,286 psi
(d) No, projected 28-day strength is 3,500 psi
Question 15
A project engineer is planning a concrete placement using a pump. The pump must deliver concrete to a point 120 ft horizontally and 40 ft vertically from the pump location. Using the rule of thumb that 1 ft of vertical pumping equals 8 ft of horizontal pumping, what is the equivalent horizontal pumping distance?
(a) 160 ft
(b) 280 ft
(c) 320 ft
(d) 440 ft
Question 16
A contractor is driving steel H-piles using a diesel hammer. The hammer has a rated energy of 42,000 ft-lb per blow. The piles must be driven to a bearing capacity of 120 tons. Using the Engineering News formula with a safety factor of 6 and assuming 0.5 inches of penetration per blow at final set, what is the allowable pile capacity?
(a) 105 tons
(b) 117 tons
(c) 140 tons
(d) 84 tons
Question 17
A site engineer is designing a temporary access ramp for construction equipment. The ramp must rise 8 ft vertically over a horizontal distance that provides a maximum slope of 12%. What is the minimum horizontal length required for the ramp?
(a) 58.7 ft
(b) 66.7 ft
(c) 72.3 ft
(d) 80.0 ft
Question 18
A concrete contractor is evaluating the use of fly ash as a partial cement replacement. The mix design calls for 600 lb of cementitious material per cubic yard. If 25% of the cement is replaced by fly ash (by weight), and cement costs $120/ton while fly ash costs $45/ton, what is the cost savings per cubic yard of concrete for cementitious materials?
(a) $5.63
(b) $3.38
(c) $4.22
(d) $2.81
Question 19
A grading contractor is using a bulldozer to push material. The dozer has a blade capacity of 12 LCY and operates with an efficiency of 45 minutes per hour. The push distance is 200 ft, resulting in a cycle time of 2.5 minutes. The material has a swell of 18%. What is the hourly production in bank cubic yards?
(a) 82 BCY/hr
(b) 97 BCY/hr
(c) 73 BCY/hr
(d) 115 BCY/hr
Question 20
A construction manager is planning the erection of structural steel for a building. A steel beam weighing 12,500 lb must be lifted and placed. The rigging consists of a two-leg sling with each leg at a 60° angle from vertical. What is the minimum required capacity of each sling leg, assuming no additional safety factors beyond the geometric configuration?
(a) 6,250 lb
(b) 7,217 lb
(c) 12,500 lb
(d) 14,434 lb
