CGN 3501C Exam 1 Questions and Answers Latest Update 2025/2026
L.A. Abrasion Test - Answers Purpose- To test the hardness and resistance of an aggregate.
Reported- as percentage loss
Meaning- how much of the material was lost to abrasion.
Threshold- must be less than 45% of the original material
Soundness Test - Answers Purpose- tests how resistive aggregate is to weathering, specifically
changes in temp. freeze-thaw conditions.
Reported- Weighted average of % weight loss after test
Meaning- how much the the oringal material was lost due to weathering
Threshold- must be less than 12% loss
Sieve Analysis - Answers Purpose- determines the size of aggregate being used.
Reported- as falling through a certain type of sieve.
Meaning- tells you how large your aggregate that you will use will be with cement.
Potential Reactivity - Answers Purpose- determines how reactive aggregate is with cement.
Reported- by measuring the change in length of a mortar bar
Meaning- the more reactive the more change that the concrete will go through, measures alakali
reactivity.
Threshold- shouldn't be greater than .05% after 3 months
Organic Impurity Test - Answers Purpose- measures the amount of organic material within
aggregate.
Reported- by color of liquid, the darker the liquid the more organic compounds within the
aggregate.
Meaning- how much organic material is in sand or another aggregate.
Threshold- Lighter color is desirable
Materials Finer than No. 200 Sieve - Answers Purpose- to measure how much material passes a
No. 200 sieve
Reported- as a percentage of how much falls through.
, Threshold- 1% for coarse aggregate, 3-5% for fine aggregate
Clay Lumps and Friable Particles in Aggregate - Answers Purpose- To find how much clay and
friable particles are present in aggregate.
Reported- in % by weight.
Threshold- 3% for fine aggregate, 2-10% for coarse aggregate.
Specific Gravity Test - Answers Purpose- is used to define the weight or density of a liquid as
compared to the density of an equal volume of water at a specified temperature.
Measured- Wt.in air/(wt in air- wt in water)
Reported-
C4AF - Answers Contributes little to strength, but helps reduce cost.
C3A - Answers contributes to early strength. High amounts can leave it vulnerable to sulfate
attacks.
C2S - Answers contributes to strength after one week, hydrates and hardens slowly.
C3S - Answers contributes to early set time and initial strength, hydrates and hardens rapidly.
Type 1 Portland Cement - Answers General use. No limits placed.
Type 2 Portland Cement - Answers Moderate sulfate resistance and heat of hydration
Type 3 Portland Cement - Answers high early strength
Type 4 Portland Cement - Answers low heat of hydration
Type 5 Portland Cement - Answers High sulfate resistance.
Pozzolan - Answers A siliceous material, such as fly ash, that reacts chemically with slaked lime
in the presence of moisture to form a slow-hardening cement, named after a natural cement
from pozzuoli, an ancient roman town near vesuvius.
Characteristics of Pozzolanic Reaction - Answers Slow reaction, consumes calcium hydroxide,
large capillary spaces are filled up by the reaction.
Blast Furnace Slag - Answers self-cementing. consumes calcium hydroxide during the reaction.
Hydraulic Cement - Answers Hardens by reacting with water to form a water-resistant product.
The presence of air is not required. Ex. Portland Cement
Non-hydraulic cement - Answers reacts with water to form a product which is not stable in
water. When hydrated, reacts with air. Ex. quick lime
L.A. Abrasion Test - Answers Purpose- To test the hardness and resistance of an aggregate.
Reported- as percentage loss
Meaning- how much of the material was lost to abrasion.
Threshold- must be less than 45% of the original material
Soundness Test - Answers Purpose- tests how resistive aggregate is to weathering, specifically
changes in temp. freeze-thaw conditions.
Reported- Weighted average of % weight loss after test
Meaning- how much the the oringal material was lost due to weathering
Threshold- must be less than 12% loss
Sieve Analysis - Answers Purpose- determines the size of aggregate being used.
Reported- as falling through a certain type of sieve.
Meaning- tells you how large your aggregate that you will use will be with cement.
Potential Reactivity - Answers Purpose- determines how reactive aggregate is with cement.
Reported- by measuring the change in length of a mortar bar
Meaning- the more reactive the more change that the concrete will go through, measures alakali
reactivity.
Threshold- shouldn't be greater than .05% after 3 months
Organic Impurity Test - Answers Purpose- measures the amount of organic material within
aggregate.
Reported- by color of liquid, the darker the liquid the more organic compounds within the
aggregate.
Meaning- how much organic material is in sand or another aggregate.
Threshold- Lighter color is desirable
Materials Finer than No. 200 Sieve - Answers Purpose- to measure how much material passes a
No. 200 sieve
Reported- as a percentage of how much falls through.
, Threshold- 1% for coarse aggregate, 3-5% for fine aggregate
Clay Lumps and Friable Particles in Aggregate - Answers Purpose- To find how much clay and
friable particles are present in aggregate.
Reported- in % by weight.
Threshold- 3% for fine aggregate, 2-10% for coarse aggregate.
Specific Gravity Test - Answers Purpose- is used to define the weight or density of a liquid as
compared to the density of an equal volume of water at a specified temperature.
Measured- Wt.in air/(wt in air- wt in water)
Reported-
C4AF - Answers Contributes little to strength, but helps reduce cost.
C3A - Answers contributes to early strength. High amounts can leave it vulnerable to sulfate
attacks.
C2S - Answers contributes to strength after one week, hydrates and hardens slowly.
C3S - Answers contributes to early set time and initial strength, hydrates and hardens rapidly.
Type 1 Portland Cement - Answers General use. No limits placed.
Type 2 Portland Cement - Answers Moderate sulfate resistance and heat of hydration
Type 3 Portland Cement - Answers high early strength
Type 4 Portland Cement - Answers low heat of hydration
Type 5 Portland Cement - Answers High sulfate resistance.
Pozzolan - Answers A siliceous material, such as fly ash, that reacts chemically with slaked lime
in the presence of moisture to form a slow-hardening cement, named after a natural cement
from pozzuoli, an ancient roman town near vesuvius.
Characteristics of Pozzolanic Reaction - Answers Slow reaction, consumes calcium hydroxide,
large capillary spaces are filled up by the reaction.
Blast Furnace Slag - Answers self-cementing. consumes calcium hydroxide during the reaction.
Hydraulic Cement - Answers Hardens by reacting with water to form a water-resistant product.
The presence of air is not required. Ex. Portland Cement
Non-hydraulic cement - Answers reacts with water to form a product which is not stable in
water. When hydrated, reacts with air. Ex. quick lime
