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Question 1. Which property of fresh concrete is primarily measured by the slump test? A) Air content B) Temperature C) Workability D) Strength development Answer: C Explanation: The slump test measures the consistency or workability of fresh concrete by indicating how much it will slump under its own weight. Question 2. The water‑cement ratio has the greatest effect on which characteristic of hardened concrete? A) Color B) Compressive strength C) Slump D) Setting time Answer: B Explanation: A lower water‑cement ratio generally yields higher compressive strength, while a higher ratio reduces strength. Question 3. Which type of cement is most commonly specified for general‑purpose concrete in Florida? A) Type I Portland cement B) Type II sulfate‑resistant cement C) Type III high‑early strength cement D) Type IV low‑heat cement Answer: A Explanation: Type I is the standard ordinary Portland cement used for most non‑specialized concrete applications. Question 4. Air‑entraining admixtures are added to concrete primarily to improve resistance to:
A) Alkali‑silica reaction B) Freeze‑thaw cycles C) High early strength D) Sulfate attack Answer: B Explanation: Entrained air provides microscopic voids that allow water to expand upon freezing, reducing damage from freeze‑thaw cycles. Question 5. When batching ready‑mix concrete, which of the following is the most critical factor to ensure uniformity? A) Mixing time B) Truck tire pressure C) Ambient humidity D) Delivery speed Answer: A Explanation: Adequate mixing time ensures that all ingredients are uniformly distributed throughout the batch. Question 6. The standard method for determining the air content of fresh concrete in the field is: A) Thermometer test B) Pressure‑meter test C) Slump test D) Penetrometer test Answer: B Explanation: The pressure‑meter (or pressure‑type) method measures the volume of air entrapped in fresh concrete. Question 7. Which aggregate size is typically used as fine aggregate in concrete mixes? A) 0‑3/8 inch B) 0‑1/2 inch
Explanation: The vapor barrier is installed over the compacted base to prevent moisture migration from the soil into the slab. Question 11. The minimum thickness for a vapor barrier under a residential concrete slab in Florida is: A) 2 mm B) 4 mm C) 6 mm D) 10 mm Answer: B Explanation: Florida building codes typically require a minimum 4 mm (≈ 1/8‑in) polyethylene vapor barrier. Question 12. Which equipment is most appropriate for compacting a granular subbase to achieve required bearing capacity? A) Plate compactor B) Concrete pump C) Concrete mixer truck D) Vibratory screed Answer: A Explanation: A plate compactor provides the necessary impact to densify granular material. Question 13. When installing keyways for a concrete wall, the purpose of the keyway is to: A) Provide a conduit for utilities B) Increase shear resistance between wall and footing C) Allow for thermal expansion D. Reduce concrete weight Answer: B Explanation: Keyways create a mechanical interlock that enhances shear transfer between wall and footing.
Question 14. The primary function of a capillary break in a slab‑on‑grade system is to: A) Prevent moisture wicking from the subgrade into the slab B) Increase slab thickness C) Provide a decorative surface D) Accelerate curing Answer: A Explanation: A capillary break (often a rigid insulation layer) interrupts moisture movement by capillary action. Question 15. Which formwork material is most commonly used for creating curved concrete walls? A) Plywood panels B) Steel panels C) Flexible plastic sheeting D. Pre‑fabricated aluminum forms Answer: C Explanation: Flexible plastic or rubber form liners can be shaped to create smooth curved surfaces. Question 16. The lateral pressure exerted by fresh concrete on formwork is greatest when: A) The concrete temperature is low B) The concrete slump is low (stiff mix) C) The concrete slump is high (fluid mix) D. The formwork is vertical Answer: C Explanation: A more fluid mix exerts higher hydrostatic pressure on the forms. Question 17. According to OSHA, the minimum distance a worker must stay from the edge of an unshored trench that is 5 ft deep is: A) 1 ft
C) Pour the concrete directly onto the reinforcement. D. Shake the forms vigorously after placement. Answer: B Explanation: A chute placed near the reinforcement reduces the distance the concrete falls, minimizing displacement. Question 21. Which method of consolidation is most effective for dense reinforcement areas? A) Hand tamping B) External vibrators only C) Internal (immersed) vibrators D. Surface troweling Answer: C Explanation: Internal vibrators penetrate the concrete and are more effective at consolidating around dense reinforcement. Question 22. The appropriate time to begin screeding a concrete slab after placement is: A) Immediately, before any settlement occurs B) After the concrete has set to a firm state (approximately 30‑ 45 min) C) After the concrete reaches 70 % of its ultimate strength D. After the surface has fully hardened Answer: B Explanation: Screeding should begin once the concrete has stiffened enough to support the screed without excessive slumping. Question 23. A broom finish is typically applied to which type of concrete surface? A) Interior polished floors B) Exterior sidewalks and driveways C. Structural walls D) Decorative stamped slabs Answer: B
Explanation: Broom finishes provide a slip‑resistant texture ideal for outdoor walkways. Question 24. Which of the following is a common cause of dusting on a concrete surface? A. Over‑curing with water B. Insufficient cement content in the mix C. Excessive air entrainment D. Too much finishing time before initial set Answer: D Explanation: Finishing too early can pull fine cement particles to the surface, resulting in dusting. Question 25. The recommended depth for a control joint saw‑cut in a 6‑in. thick slab is: A) ¼ of the slab thickness B) ½ of the slab thickness C) ¾ of the slab thickness D. Full thickness Answer: B Explanation: Saw cuts should be at least ½ the slab thickness to allow for effective movement control. Question 26. Which curing method is most suitable for a concrete slab exposed to high temperatures and wind? A) Curing compounds only B. Water spray continuously for 7 days C. Wet burlap coverings replaced daily D. Use of insulated blankets with a curing compound Answer: D Explanation: Insulated blankets retain moisture and temperature, while a curing compound reduces water loss. Question 27. The primary purpose of a construction joint in a concrete slab is to:
D. The width of the concrete cover Answer: B Explanation: Bearing width is the portion of the footing that directly transmits loads to the underlying soil. Question 31. To calculate the volume of concrete required for a wall, you would multiply: A) Length × Height × Width of the wall, then subtract the volume of openings. B) Length × Height only. C) Height × Width only. D. Length × Width only. Answer: A Explanation: The volume of concrete equals the overall wall dimensions minus any voids such as doors or windows. Question 32. According to OSHA, the minimum PPE required for workers handling wet concrete includes: A) Safety glasses only B) Hard hat, gloves, and steel‑toe boots C) Respirator and hearing protection D. Gloves and high‑visibility vest only Answer: B Explanation: Wet concrete poses risks of splash, impact, and foot injuries; hard hat, gloves, and steel‑toe boots are required. Question 33. In Florida, a “Notice to Owner” must be served within how many days after first furnishing labor or materials on a construction project? A) 10 days B) 30 days C) 45 days D. 60 days
Answer: B Explanation: Florida statutes require a Notice to Owner to be served within 45 days, but many contractors send it within 30 days to ensure compliance. Question 34. The primary purpose of a “shoring” system in formwork is to: A) Provide a decorative finish B) Support vertical loads from wet concrete until it gains sufficient strength C. Accelerate curing D. Reduce water demand Answer: B Explanation: Shoring holds the forms in place against the pressure of fresh concrete until the concrete can support itself. Question 35. Which of the following admixtures would you select to delay the set time of concrete in hot weather? A) Accelerating admixture B) Retarding admixture C) Air‑entraining admixture D. Superplasticizer Answer: B Explanation: Retarding admixtures slow down the hydration process, extending set time in hot conditions. Question 36. The term “bleed water” in fresh concrete refers to: A) Water that evaporates from the surface B) Water that rises to the surface due to settlement of solids C) Water added during mixing to increase slump D. Water that is absorbed by aggregates Answer: B
Question 40. Which of the following is the most effective method to prevent cracking due to thermal shrinkage in large concrete pours? A) Increase water‑cement ratio B) Use a high‑early strength cement C) Apply a curing compound immediately after finishing D. Install expansion joints at regular intervals Answer: D Explanation: Expansion (or contraction) joints accommodate movement caused by temperature changes, reducing cracking. Question 41. The term “sag factor” in concrete placement refers to: A) The amount of slump loss over time B) The tendency of concrete to flow downhill before it sets C) The reduction in air content due to vibration D. The increase in temperature during curing Answer: B Explanation: Sag factor describes how much concrete will flow or “sag” under its own weight, important for vertical pours. Question 42. When using a concrete pump, the maximum recommended concrete temperature for placement is: A) 50 °F (10 °C) B) 70 °F (21 °C) C) 90 °F (32 °C) D. 110 °F (43 °C) Answer: C Explanation: Temperatures above 90 °F can cause rapid setting and increased pump pressure; thus 90 °F is the typical upper limit.
Question 43. In a reinforced concrete column, the term “lap splice” means: A) Overlapping two bars end‑to‑end to achieve required length B) Bending a bar into a hook C. Cutting a bar to a shorter length D. Welding two bars together Answer: A Explanation: A lap splice provides continuity by overlapping the reinforcing bars for a specified length. Question 44. The most common type of form release agent used on metal forms is: A) Oil‑based wax B) Water‑based polymer C. Solvent‑based silicone D. Calcium chloride Answer: C Explanation: Solvent‑based silicone releases provide a thin, non‑sticky film that works well on metal surfaces. Question 45. Which of the following is NOT a typical requirement for a concrete curing compound? A) Form a film that reduces water loss B) Remain effective under high temperatures C) Increase the concrete’s compressive strength directly D. Be compatible with the concrete mix Answer: C Explanation: Curing compounds do not chemically increase strength; they preserve moisture to allow proper hydration. Question 46. The term “modulus of rupture” refers to: A) The tensile strength of concrete measured by flexural testing B) The compressive strength of concrete cylinders
Explanation: A/C ratio is the weight of aggregates divided by the weight of cement, influencing mix durability and workability. Question 50. Which of the following is the most common cause of “blistering” on a concrete surface? A) Excessive air entrainment B) Rapid drying of the surface while the interior remains wet C) Use of too much water‑reducing admixture D. Over‑vibration of the concrete Answer: B Explanation: Blistering occurs when surface moisture evaporates quickly, creating pressure that lifts the surface. Question 51. The term “plastic shrinkage” refers to cracks that develop: A) After the concrete has hardened fully B) Within the first few hours while the concrete is still plastic C) Due to thermal contraction after curing D. From corrosion of reinforcement Answer: B Explanation: Plastic shrinkage cracks form while the concrete is still in its plastic state, often caused by rapid moisture loss. Question 52. For a concrete slab that will be exposed to de‑icing salts, the most appropriate cement type is: A) Type I B) Type II C) Type III D. Type V sulfate‑resistant cement Answer: D Explanation: Type V cement offers high sulfate resistance, which also improves resistance to chloride attack from de‑icing salts.
Question 53. In concrete placement, “cold joints” are best avoided by: A) Allowing the first pour to set completely before the next pour B) Using a bonding agent on the surface of the first pour before the second pour C) Adding extra water to the second pour D. Reducing the slump of the second pour Answer: B Explanation: Applying a bonding agent (or keeping the surface moist) helps achieve a monolithic bond between successive pours. Question 54. Which of the following best describes “sulfate attack” on concrete? A) Expansion caused by reaction of sulfates with calcium aluminate phases, leading to cracking B) Corrosion of steel reinforcement due to chloride ions C. Freeze‑thaw damage caused by entrained air D. Alkali‑silica reaction causing gel formation Answer: A Explanation: Sulfate ions react with certain cement compounds, producing expansive products that cause cracking. Question 55. The most common method for measuring the temperature of fresh concrete on a job site is: A) Infrared thermometer B) Thermocouple probe inserted into the mix C) Surface temperature gauge D. Slump cone temperature reading Answer: B Explanation: A thermocouple or temperature probe inserted into the concrete provides an accurate internal temperature. Question 56. In a concrete mix design, the term “minimum slump” is specified to ensure:
C) Air‑entrained mixes D. High‑early strength mixes Answer: B Explanation: Excess water in a high‑slump mix increases the likelihood of bleed water rising to the surface. Question 60. Which of the following OSHA standards applies specifically to excavation and trench safety? A) 29 CFR 1926. B) 29 CFR 1926. C. 29 CFR 1926. D. 29 CFR 1926. Answer: A Explanation: OSHA 29 CFR 1926.651 covers requirements for protective systems in excavations and trenches. Question 61. In a concrete mix, the “fineness modulus” is used to describe: A) The average size of the fine aggregate particles B) The water‑cement ratio C. The amount of cement in the mix D. The air content of the mix Answer: A Explanation: Fineness modulus is an index number that indicates the coarseness or fineness of fine aggregates. Question 62. Which of the following is the most appropriate method for protecting freshly placed concrete from rapid drying in a hot, windy environment? A) Applying a thin layer of oil on the surface B) Covering with wet burlap or plastic sheeting and keeping it moist C. Using a high‑range water reducer
D. Increasing the slump of the mix Answer: B Explanation: Wet burlap or plastic retains moisture and reduces evaporation, protecting the concrete from rapid drying. Question 63. When calculating the weight of reinforcement for a concrete slab, you must consider: A) Only the length of each bar B) Length, cross‑sectional area, and unit weight of steel C. Only the number of bars D. Only the spacing between bars Answer: B Explanation: Reinforcement weight = length × cross‑sectional area × unit weight (≈ 490 lb/ft³ for steel). Question 64. The primary purpose of a “saw‑cut” control joint is to: A) Reduce the slab’s overall weight B) Create a weakened plane where shrinkage cracks can form in a controlled manner C. Increase the slab’s compressive strength D. Allow for water drainage Answer: B Explanation: Saw cuts produce a predetermined weak plane that directs shrinkage cracking. Question 65. Which of the following statements about “alkali‑silica reaction” (ASR) is correct? A) It is caused by the reaction of alkalis with sulfates in cement. B) It leads to expansion and cracking due to gel formation. C. It only occurs in high‑temperature curing. D. It is prevented by adding extra water. Answer: B Explanation: ASR produces an expansive silica gel that can cause cracking in concrete.
