Construction Materials & Methods Flashcards

A concrete mix design calls for a water-to-cement (w/c) ratio of 0.45. If 400 lbs of cement is used per cubic yard, how much water (in lbs) is required?

Answer: 180 lbs

Water weight = w/c ratio × cement weight = 0.45 × 400 = 180 lbs of water per cubic yard.

Which type of pile is most appropriate when driving through soft soils to reach a hard bearing stratum?

Answer: End-bearing pile

End-bearing piles transfer structural loads through weak soils to a firm layer such as rock or dense gravel at the pile tip.

In roofing, what does 'R-value' measure?

Answer: Thermal resistance of insulation

R-value is a measure of thermal resistance — the higher the R-value, the greater the insulating effectiveness of the material.

What is the function of 'admixture' Type C (accelerator) in concrete?

Answer: Speeds up hydration to allow earlier form removal

Accelerating admixtures speed up the hydration of cement, increasing early strength gain and allowing earlier form stripping, especially useful in cold weather.

When inspecting structural lumber, the designation 'No. 2 & Btr' means the lumber is:

Answer: No. 2 grade or higher quality

'No. 2 & Better' (No. 2 & Btr) means the lumber meets at least No. 2 grade standards and may include No. 1 or Select Structural grade material.

In welding inspection, what does the term 'undercut' describe?

Answer: A groove melted into base metal adjacent to the weld toe left unfilled

Undercut is a groove or channel burned into the base metal at the weld toe that is not filled by weld metal, creating a stress concentration.

What ASTM standard governs the specification for deformed and plain steel bars for concrete reinforcement?

Answer: ASTM A615

ASTM A615 is the standard specification for deformed and plain carbon-steel bars for concrete reinforcement, covering grades 40, 60, and 80.