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Concrete Materials

Concrete Materials Final Spring 2012

Question	Answer
Low temperature curing results in high early strength but lower ultimate	False
The main hydration compound responsible for strength of Portland cement concrete is ettringite	False
The use of air-entraining admixture would typically allow the reduction of the w/c ratio required for a given work ability	True
Effectiveness of a mineral admixture as a pozzolanic material can be assessed through quantifying lime consumption of that admixture when incorporated with cement in a mix	True
Increasing the fineness modulus of sand increases paste requirement
Increasing maximum aggregate size results in a decrease in the compressive strength of concrete in lean mixes while for mix mixtures the opposite is true	False
OD AND SSD are considered reference moisture states for aggregates	True
In order to increase sulfate durability of a structure, a portland cement of high tricalcium aluminate content should be selected.	False
The main contributiion to heat evolution during the hydration of Portland cement is primarily from C2S hydration	False
In Preparing a trial batch for a specific concrete mix, it is important to batch by mass as opposed to batching by volume	True
The initial set of a cement paste can be correlated to the end of induction stage of tricalcium sillicate hydration
For mass elements or mass structures it is important to use Portland cement that is high in its tricalcium aluminate and tricalcium silicate content	False
In order to improve durability of reinforced structures, it is important to incorporate a mineral admixture such as silica fume or fly ash	True
The primary focus of civil engineers in designing a structural element is to aim for the highest compressive strength without accounting for durability	False
For mass concrete, cement fineness has no consequences on structure durability	False
The heat of hydration of Portland Cement paste will not be affected by a large increase in cement fineness	False
For the same workability, a low w/c ratio design will yield concrete that is strong a durable	True
Reducing the transition zone in concrete has no effect on concrete strength	False
The pH of the pore solution is affected by the alkali content of Portland cement
It is important to limit periclase in portland cement because it can generate unsoundness in concrete elements	True
The amount of sulfur trioxide in portland cement is not of significance on a sulfate durability	False
On hydration anyhydrous portland cement doubles its volume	True
The moisture content of aggregates has to be accounted for to ensure a constant w/c ratio in making concrete trial batches	True
Bogue calculations give an accurate account of the crystalline phases in portland cements	False
For lean mixes, increasing nominal maximum aggregate size increases the compressive strength of the concrete	True

Created by: pymptytedablak53 on 2012-04-29

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Concrete Materials

Concrete Materials Final Spring 2012