Glencoe: 15

Question 1

Admixture:

Answer 1

Ingredient to concrete that changes it physical or chemical characteristics.
Some make concrete more workable, some increase its strength.

Question 2

Air-Entraining Admixtures:

Answer 2

introduce tiny air bubbles to concrete to increase concretes durability when exposed to moisture and frequent freeze and thaw cycles.

Question 3

Retarding admixtures

Answer 3

makes concrete set up at a slower rate. Useful in hot weather where its difficult to finish placement before concrete normally sets up

Question 4

Accelerating Admixtures:

Answer 4

Increase the rate at which concrete gains strength. Important if concrete must be set up quickly. Calcium chloride is a type. It is added in liquid form to prevent problems caused by undisolved materials.

Question 5

Water-Reducing admixtures:

Answer 5

These make it possible to reduce the amount of water without reducing workability. Makes concrete stronger.

Question 6

Super-plasticizing admixtures:

Answer 6

These can do one of two things. They can make the concrete flow very easily, or they cant significantly increase its strength.

Question 7

Methods to color concrete:

Answer 7

Add in liquid colorant,
Add a layer of colored concrete over uncolored concrete
Or dust powdered colorant over the surface of wet concrete which is absorbed.

Question 8

Trowel:

Answer 8

metal tool with a wide flat blade that is used for shaping and spreading substances.

Question 9

What is often the cause of problems with concrete?

Answer 9

improper finishing techniques

Question 10

Crazing:

Answer 10

Fine irregular cracks that appear within a week after concrete has been placed. Does not effect strength of concrete. Caused by excessive floating or spraying water during finishing.

Question 11

Plastic shrinkage cracks:

Answer 11

Series of shallow, parallel cracks in the surface. Caused by too rapid drying of concrete. Does not affect strength,

Question 12

Efflorescence:

Answer 12

whitish crystalline deposit that sometimes appears on the surface of concrete or mortar. Caused when salts in the concrete mix with water or moisture vapor and rise to the surface. Does not affect strength

Question 13

Cracks:

Answer 13

cracks that extend through concrete can significantly reduce strength and long-term durability. Many causes such as improperly compacted sub-grades and excessive water in mix.

Question 14

Chalking:

Answer 14

formation of loose powder on the surface of hardened concrete. Sometimes called dusting. Surface is so weak that it can be crushed by surface traffic or even scratched with light pressure. Sometimes the result of finishing before the surface water has dissapeared.

Question 15

Scale:

Answer 15

widespread flaking of a hardened concrete surface. Often the result of exposing concrete to freeze/thaw extremes.

Question 16

Clinker:

Answer 16

In portland cement, heating changes chemical composition until they form small clumps called clinker.

Question 17

Concrete is measured by:

Answer 17

cubic yard

Question 18

transit mix:

Answer 18

trucks mix the concerete on way to site. Also called ready mix

Question 19

Short load:

Answer 19

truck carries all ingredients to the site and then it is mixed there.

Question 20

Plot plan:

Answer 20

part of the house plans that shows the location of the building on the lot along with related land elevations.

Question 21

Site layout:

Answer 21

The location of the building is marked out on the land itself to position the house correctly on the lot.

Question 22

Factors which influence site layout:

Answer 22

zoning codes, utilities, privacy or ledge(rock below grade).

Question 23

Two basic methods to accurately determine the location of proposed building on a property.

Answer 23

Measuring from an existing reference line.

Using a surveying instrument such as a level or transit.

Question 24

Reference line

Answer 24

A building may be planned so that it is parallel to an existing line, such as a street or marked property line. Such a line can then be used as a guide.

Question 25

Types of surveying instruments:

Answer 25

Optical, Laser, or GPS

Question 26

Optical Instruments:

Answer 26

Rely on line of site observations to determine position. Users look through telecope to see a leveling rod marked with graduations in feet and fractions of a foot.

Question 27

Laser Instruments:

Answer 27

Do not use telescope. Focuses beam of light. An electronic detector is held against the leveling rod which senses the reference plane projected by laser. Can be hard to see in daylight.

Question 28

GPS Instruments:

Answer 28

newest development in surveying systems. Using signals from 24 satellites the detector can track its location with great accuracy.