CE 381 Exam 1

Following is the results of a sieve analysis test on an aggregate sample. Fill in all cells with the appropriate values

% retained = (grams retained at sieve size)/(total grams retained) cumulative % retained = (add up % retained at each size) cumulative % passing = (100 - cumulative % retained)

Define Specific Gravity

(Density of sample)/(Density of water)

Define factor of safety

(ultimate(stress or strength))/(actual(stress or strength))

Describe three advantages and three disadvantages of using fly ash with portland cement

Advantages: increase workability increase strength less reactivity Disadvantages: more brittle lower heat hard to find quality ash

Aggregate should have which of the following properties? a) Angular b) Durable c) Free of Soil d) Dry

All

Define young's modulus (the ratio of what two variables?) and state what it tells you

E=(stress)/(strain) It tells us about the elasticity of a material

Describe the differences between hydraulic and non hydraulic cement

Hydraulic is able to harden when wet or dry Non hydraulic only hardens when dry

What are the three raw materials that are used to make iron?

Iron ore, coke, limestone

What are the main raw ingredients in portland cement?

Limestone, clay, shale

Describe the difference between specific gravity and unit weight

Unit weight is the required weight to fill a unit volume

What are the two different ways to estimate the yield stress of a material, given it's stress strain curve? (give the name of each)

a 0.2% offset of the curve at y = 0.04 in.

Following are weights for a specific gravity test on coarse aggregate: Weight of SSD sample 4000 grams Weight of saturated sample submerged in water 2550 grams Weight of OD sample 3950 grams a) Calculate SSD specific gravity b) Calculate OD specific gravity c) Calculate % absorption

a) (Weight of SSD sample)/((Weight of SSD sample) - (Weight of saturated sample submerged in water)) b) OD/(SSD - Sub) c) ((Weight of SSD sample) - (Weight of OD sample))/(Weight of OD sample)

Generally speaking, aggregates can be classified by weight as normal, lightweight or heavyweight. The classification is dependent on the aggregate's mineral composition. Below is a list of common aggreates. Classify each as N-normal, L-lightweight, or H-heavyweight. a) Barite b) Pumice c) Calcite (limestone) d) Quartz (siliceous)

a) H b) L c) N d) H

Which of the following aggregate grading size numbers would have the largest nominal size particles? a) #4 b) #357 c) #8 d) #467

b) #357

Reducing the carbon content of steel will: a) decrease ductility b) decreases brittleness c) increases strength d) serves as an alloying agent e) both a and c

b) decreases brittleness

A rounded river gravel would be better suited for use in the following: a) hot mix asphalt pavement b) portland cement concrete pavement c) it could be used equally for both d) it should not be used in either type of pavement

b) portland cement concrete pavement

______ refers to the relative variability of repeat measurements under carefully controlled conditions a) accuracy b) precision c) quality control d) bias

b) precision

When test results are concentrated near a value which is incorrect, these measurements are: a) accurate b) precise and accurate c) biased d) normally distributed about the true value

c) biased

The L.A. abrasion test is used to measure an aggregates: a)texture b)gradation c)durability d)specific gravity

c) durability

Economic factors are a significant part of selecting a material for construction. List four costs which should be evaluated when selecting materials

cost of raw material cost of transportation cost of storage cost of labor needed how much material is needed Type of material

A sieve analysis is conducted on aggregate to: a) Check for potential alkali-aggregate size particles b) Determine the specific gravity of the large size particles c) Analyze the moisture and compactive properties d) Seperate the aggregate particles based on size e) None of the above

d) Seperate the aggregate particles based on size

The absorption of a saturated aggregate sample will always be a) equal to the total moisture content b) equal to the aggregate's moisture content in the existing condition c) greater than its SSD moisture content d) none of these

d) none of these

On the stress/strain curve for steel rebar below, label the following: yield point, ultimate strength, strength at fracture, proportional limit. What is the approximate yield strength?

proportional limit is the top of the linear portion yield point is just after proportional limit where the line starts to dip ultimate strength is the highest point on the graph strength at fracture is the last point on the graph approximate yield strength is at yield point