What does a gas-forming agent do when added to concrete?

What will be an ideal response?


Gas-forming agents are added to concrete or grout to cause a slight expansion in it before it hardens. Aluminum powder, one of several gas-forming agents in use, reacts with the hydroxides in hydrating cement and produces small hydrogen-gas bubbles. This also helps eliminate voids caused by settlement of the concrete or grout. A typical application consists of expanding the grout under a difficult-to-reach machine base or column to be certain the area is fully grouted. After concrete or grout has hardened, gas-forming agents will not overcome shrinkage. When they are used in large amounts, gas-forming agents produce lightweight cellular concrete.

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____ for cast-in-place concrete may be constructed of lumber, plywood, aluminum, steel, and combinations of these materials.

A. Loadwork B. Form standards C. Formwork D. Form loads

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On residential blueprints, ____________________ are used to provide the sizes and other pertinent information about the various doors and windows used in the building.

Fill in the blank(s) with the appropriate word(s).

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The phases of a planned maintenance service call are:

A) Operational checks and troubleshooting. B) Routine maintenance, troubleshooting, and replacing parts that cause problems on many systems. C) Routine maintenance, pre-start inspection, operational checks, and troubleshooting. D) Routine maintenance and operational checks.

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?A Sydney tube is often paired with a parabolic reflector fixed behind each tube.

Answer the following statement true (T) or false (F)

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