Construction Trade Flashcards
Packed cinders or gravel should be used as a base for slab floors when the soil tends to retain water.
True
Concrete can be thinned to any consistency and still retain its full strength
False. Water will weaken concrete.
Slightly salty water used in mixing concrete will not harm the mixture.
False. Water should be clean and free of salt
Voids in concrete are caused by inadequate tamping, spading, or vibrating when being poured.
True
The concrete forms should be dry while mix is being poured.
False
The footing trenches should be dry when concrete is poured.
False
Clay makes a better footing base than sand or gravel.
False
Concrete is fully cured in seven days.
False. The longer it has to cure the stronger it will be.
It is permissible to add more water to concrete if it begins to lose its workability after one hour of working with it.
False. Concrete begins to set about 30 minutes after it is mixed with water and should not be thinned again.
It is good procedure to use a membrane such as a roofing felt between the concrete slab floor and it’s base.
True
The slump test determines the consistency of concrete.
True. This test shows how much a given amount of concrete sags when emptied from a container
Beach sand is not advisable to use in some mixtures
True. Sand containing any salt should not be used.
A good mixture for a footing consist of one part cement, four parts sand, and three parts rock gravel.
False. A good mixture is 1 part cement, 2 1/4 part sand, and 3 parts gravel.
Forms of concrete soffits can be stripped within three days.
False. 7 days should be the minimum.
Expansion joints or lines should be provided for the expansion and contraction of the concrete walks
True
A broom finish or slightly rough finish is better than a steel trowel finish for a walk.
True
Terrazzo is a special mixture of concrete
True
Concrete should be mixed dry before water is added.
True
Concrete should be cured by sprinkling with water daily for about seven days.
True
Monolithic construction in concrete means one piece concrete construction free of construction joints.
True
Monolithic topping is the finish topping.
True
Excessive spading, tamping, or vibrating of concrete will cause a separation of materials and the course aggregate will settle to the bottom.
True
In pouring concrete from an excessive distance the course aggregate have a tendency to sink to the bottom.
True
Sand which contains more than 10% loam or clay can be used in the concrete mix.
False. Fine aggregates should consist of natural sand or screenings of crushed rock and should be free from injurious amounts of loam, clay, or organic material.
Anchor bolts should be put into the concrete after the concrete has started to set.
False. The bolts should be put in as soon as possible in order to have a good grip.
The picot test is a test for abrasiveness of concrete.
True