225 Quiz: Chapters 2,4,&5

Concrete can contribute in how many categories in LEED for New Construction and Major Renovations (NC) 2009 system?

15

Water containing more than _______ ppm of dissolved solids should be tested for its effect on strength and time of set before being used in concrete.

2000

When cement fines are returned to the concrete in recycled wash water, ________ ppm can be tolerated.

50000

According to ASTM C1602, concrete tested according to ASTM C31 and C39 using a questionable water supply should produce a compressive strength of at least _________ compared to the same mixture made with potable water.

90%

Fly ash and ground granulated blast furnace slag will generally retard the setting time. This is

a cause of significant delays and problems in cold weather, and an advantage during warm weather

Supplementary cementitious materials include

calcined clay, silica fume, fly ash, slag, calcined shale

Concrete materials should not be recycled because of the chemicals in the concrete These chemicals can percolate into the subsurface.

false

Concretes using fly ash generally exhibit more bleeding and segregation than plain concrete.

false

Fly ash, slag, calcined clay and steel generally decrease the workability of concretes of equal slump.

false

Inclusion of fly ash and silica fume will generally increase the amount of entrapped air in a concrete mix.

false

Only natural water that is drinkable and has no pronounced taste or odor can be used as mixing water for making concrete.

false

Reinforcing steel should be minimized because it is usually not made of recycled steel.

false

What are the mandatory requirements for set time deviation to certify a non-potable water source as suitable for use in concrete, according to ASTM C1602?

from 1 hour earlier to 1.5 hours later

Pervious concrete is

made using similar size aggregate and no fine aggregates

Using mixing water that contains sugar in quantities of 0.25% or more by weight of cement _________.

may cause rapid setting and substantial reduction in 28-day strength

Using supplementary cementing materials can

produce concretes resistant to scaling caused by deicing chemicals in the freeze thaw environment, reduce permeability and absorption of concrete, control of alkali-silica reactivity, and improve sulfate resitance

Seawater should not be used in concrete that contains any _________.

reinforcement

Thermal mass of concrete structures can

shift energy demand to off-peak time periods when utility rates are lower, reduce needed HVAC equipment capacity, and moderate indoor temperature extremes and reduce peak heating and cooling loads

Water of questionable suitability must be tested for _________ and _________ prior to use in making concrete.

strength; set time

Algae can cause excessive strength reduction either by influencing cement hydration or by causing a large amount of air to be entrained in the concrete.

true

Concrete containing ground slags of comparable fineness of cement tend to show an increased rate of bleeding with no impact on segregation. However, if finer ground than cement slag is used, they reduce bleeding.

true

Concrete has a large percentage of locally extracted and manufactured ingredients that reduce shipping distances and related fossil fuel consumption

true

Concrete's durability and longevity contributes to its sustainability because it shouldn't have to be replaced as often as other building materials conserving future building materials.

true

Fly ash can reduce permeability and protect rebar from corrosion. Reduced permeability also helps with reducing chemical attack.

true

Permeable paver systems decrease the need for other storm water management systems.

true

Silica fume contributes to early strength from 3-28 days.

true

Supplementary cementitious materials are pre-consumer recycled materials used in concrete.

true

Supplementary cementitious materials that significantly delay set time can increase the risk of plastic shrinkage cracking.

true

The World Commission on Environment and Development defines sustainable development as "Meeting the needs of the present generation without compromising the ability of the future generations to meet their needs."

true

Volume instability is a possible harmful effect of excessive impurities in concrete mixing water.

true