NASCLA Concrete: six questions across five books

What the bulletin says, and what it leaves out

PSI's Candidate Information Bulletin (updated 7 Jul 2026) gives the area name and its count of 6, with no topic list. It allows ACI 318-14 or ACI 318-19 (2022), and says code questions use only the listed code editions. The topics below are our reading of the area name and the reference list.

Which book for which question

Our suggestion from the titles. NASCLA publishes no mapping.

Because two editions of ACI 318 are allowed, never answer a code limit from memory. Look it up in your copy.

Topics to cover

• Materials. Cement, water, aggregates, admixtures and supplementary materials such as fly ash or slag.
• Water-cement ratio. Lower ratios give higher strength and better durability, as long as the mix can still be placed and consolidated. Water added at the truck raises the ratio.
• Testing. Slump measures consistency, not strength. Strength comes from cylinders made in the field and broken in a lab.
• Placing and finishing. Avoid long drops that separate the mix, consolidate without over-vibrating, and do not finish while bleed water is on the surface.
• Joints. Control joints make cracks form where you want them. Isolation joints separate a slab from columns and walls. Construction joints are where one placement stops.
• Curing. Keep the concrete moist and at a suitable temperature so it keeps gaining strength.
• Reinforcing, post-tensioning and precast. Bar sizes, cover, chairs and laps; tendon placing and stressing; lifting precast only at its designed points and bracing it until connected.
• Safety. No construction loads on concrete unless the employer has information from a person qualified in structural design that it can carry them (1926.701(a)). Protruding rebar workers could fall onto must be guarded against impalement (1926.701(b)). Both confirmed in the eCFR text current to 4 Nov 2026.

Worked examples

All numbers are invented. Each is worked two ways.

Water-cement ratio. A mix has 517 lb of cement and 30 gallons of water per cubic yard. Water weighs about 8.33 lb per gallon, so 30 x 8.33 = 249.9 lb. The ratio is 249.9 / 517 = 0.48. Check: 517 x 0.48 = 248.2, close to 249.9; to three places the ratio is 0.483.

Slab yardage. A slab is 50 ft by 36 ft and 4 in. thick. Area = 50 x 36 = 1,800 square feet. Volume = 1,800 x (4 / 12) = 600 cubic feet, and 600 / 27 = 22.22 cubic yards. With 8% waste, 22.22 x 1.08 = 24.0, so order 24 cubic yards. Check: 1,800 x 4 = 7,200, divided by 12 is 600 cubic feet.

Footing yardage. A continuous footing is 180 ft long, 2 ft wide and 1 ft deep. Volume = 180 x 2 x 1 = 360 cubic feet, and 360 / 27 = 13.33 cubic yards. Check: 13.33 x 27 = 360 (to rounding).

Bar size. For common inch-pound bar sizes, the bar number is the nominal diameter in eighths of an inch, so a #6 bar is about 6/8 = 3/4 in. Check: 0.75 x 8 = 6.

Common mix-ups

• Slump is not strength. A higher slump means a wetter, more fluid mix.
• Water at the site is not the fix. More workability comes from an admixture or an allowed mix change.
• Thickness in inches. 4 in. is 0.333 ft, not 4. Convert before you multiply.
• Field practice versus code. A finishing question goes to the field guide; a cover or strength requirement goes to ACI 318.

How to practice

Tab each of the five concrete books at its index and the two or three topics in the table above. Then drill: read a question, name the book in five seconds, find the topic and time yourself. Work yardage problems until the divide-by-27 step is automatic. The NASCLA study guide pairs Concrete with Site Construction, and Metals is another six-question area.

Practice it

Work slab and footing quantities with the free concrete yardage calculator.

Take the free 10-question check and see your score by subject area in minutes. It needs no signup and explains every answer.

The NASCLA Commercial course has a lesson for each of the 12 subject areas that shows which listed reference to open and how to apply it, original practice questions with every answer worked, and four timed practice exams of 115 questions on a 330-minute clock. Your scores come back by subject area, so you know where the next study hour goes. See the course.

Not affiliated with or endorsed by NASCLA or PSI. NASCLA and PSI are named only to identify the exam and its test vendor. Book titles are named only to identify them.

Sources

Show the list

• PSI Candidate Information Bulletin 1458, content outline, reference list and edition rules, updated 7 Jul 2026. Retrieved 5 Nov 2026.
• 29 CFR 1926 Subpart Q, Concrete and Masonry Construction, OSHA. Values checked against the eCFR text current to 4 Nov 2026.