Construction & Building Materials Flashcards

Which admixture is added to concrete to significantly reduce the water-cement ratio without losing workability?

Answer: Superplasticizer

Superplasticizers (high-range water reducers) allow a 20-30% reduction in water content while maintaining workability.

What is the primary purpose of curing concrete after placement?

Answer: To maintain moisture for continued hydration

Curing keeps concrete moist and at a suitable temperature so that cement hydration continues, developing strength and durability.

Structural steel used in US construction is most commonly specified under which ASTM standard?

Answer: ASTM A36

ASTM A36 is the most widely used structural carbon steel standard, with a minimum yield strength of 36 ksi.

What does the term 'modulus of rupture' measure in timber or concrete beams?

Answer: Flexural tensile strength

Modulus of rupture (MOR) is the maximum fiber stress at failure in a bending test, representing flexural tensile strength.

Which type of brick is most resistant to efflorescence due to its low water absorption?

Answer: SW (Severe Weathering) grade brick

SW grade brick has the lowest water absorption (≤17%) and is designed for severe weathering conditions, reducing salt migration and efflorescence.

In reinforced concrete design, what is the primary function of transverse (shear) reinforcement (stirrups)?

Answer: Confine concrete core and resist diagonal tension

Stirrups confine the concrete core, resist diagonal tension from shear forces, and prevent buckling of longitudinal bars.

Which asphalt mixture design method is most commonly used for heavy-traffic pavements in the United States?

Answer: Superpave Method

The Superpave (Superior Performing Asphalt Pavements) method, developed under the SHRP program, is the current US standard for mix design.