Overview

PE exam study guide for engineering materials: concrete mix design, reinforced concrete, structural steel, asphalt, and timber design.

This topic accounts for 6 out of 40 questions on the PE Civil Civil Breadth (AM) exam.

Key Concepts

Concrete Mix Design

Water-cement ratio (w/c) is the primary factor affecting concrete strength. Lower w/c = higher strength but less workability. Typical values: 0.40-0.50 for structural. ACI mix design procedure: select w/c from strength requirements, determine water content from slump and aggregate size, compute cement = water / (w/c). Air content: 4-7% for freeze-thaw exposure. Slump test (ASTM C143) measures workability.

Reinforced Concrete Beam Design

Whitney stress block: a = As*fy / (0.85*fc*b). Nominal moment: Mn = As*fy*(d - a/2). Design moment: phi*Mn where phi = 0.9 for tension-controlled. Check tension-controlled: epsilon_t = 0.003*(d-c)/c > 0.005. c = a/beta1, where beta1 = 0.85 for fc <= 4000 psi, decreasing by 0.05 per 1000 psi above 4000.

Concrete Nominal Flexural Strength Nominal Moment Capacity Mn Whitney Stress Block Depth A Beta 1 Factor Tension Steel Strain Minimum Flexural Reinforcement

Structural Steel (LRFD)

Tension: phi*Pn = min(0.90*Fy*Ag, 0.75*Fu*Ae). Compression: phi*Pn = 0.90*Fcr*Ag. Flexure: phi*Mn = 0.90*Fy*Zx (compact sections). Shear: phi*Vn = 1.00*0.6*Fy*Aw*Cv. A992 steel: Fy = 50 ksi, Fu = 65 ksi. Net area accounts for bolt holes (hole diameter = bolt + 1/16 + 1/16). Shear lag factor U reduces effective net area.

Steel Tension Yield Strength Steel Beam Column Interaction

Asphalt Mix Properties

Air voids: Va = (1 - Gmb/Gmm) x 100%. VMA (voids in mineral aggregate) = 1 - (Gmb*Ps)/(Gsb). VFA (voids filled with asphalt) = (VMA - Va)/VMA x 100%. Target air voids in place: 3-5%. Gmm is from Rice test (AASHTO T 209). Gmb is from saturated surface-dry method. Superpave mix design uses gyratory compactor.

Timber/Wood Design

Adjusted design values: F_prime = F x CD x CM x Ct x CF x CL x... CD = load duration factor (1.0 normal, 1.15 snow, 1.25 7-day, 1.6 wind, 2.0 impact). CM = wet service factor. Ct = temperature factor. CF = size factor. CL = beam stability factor. Bending: fb = M/S <= F_prime_b. Reference values from NDS Supplement.

Beam Stability Factor Cl Column Stability Factor Cp

Common Exam Question Types

Calculate concrete unit weight from batch proportions
Determine phi*Mn for a reinforced concrete beam
Compute steel tension member design strength (yielding vs rupture)
Calculate air void content of an asphalt specimen
Determine adjusted allowable bending stress for timber
Evaluate concrete slump test results against specifications

Exam Tips & Strategies

For RC beams: a = As*fy/(0.85*fc*b), then Mn = As*fy*(d-a/2). Always check tension-controlled

Steel tension: check BOTH yielding (0.90*Fy*Ag) and rupture (0.75*Fu*Ae). Take the smaller

Asphalt air voids = (1 - Gmb/Gmm) x 100%. Simple formula but commonly tested

Wood: F_prime = F x all applicable adjustment factors. CD for load duration is most important

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