Construccion

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  • Publicado : 31 de enero de 2011
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Examen 1

Cement manufacturers use a range of standard tests to ensure that the product they produce and sell conforms to the desired or required standards. Results from these tests on cement ___?___ performance of concrete in the field. |
  |   | a) accurately represent expected |
  |   | b) represent approximate |
  |   | c) do not measure |
  |   | d) can be used to extrapolate |2) | Chemical analysis, either by wet chemistry or instrumental analysis, is used to determine the oxide composition of cements. Results from these tests can be used to calculate the ___?___ compound composition. |
  |   | a) approximate |
  |   | b) potential |
  |   | c) exact |
  |   | d) hypothetical |

3) | ASTM C618 outlines the physical and chemical requirements forpozzolanic materials including natural pozzolans and by-product materials. Which pozzolan is described as having both pozzolanic and cementitious properties? |
  |   | a) Calcined clay |
  |   | b) Class F fly ash |
  |   | c) Class C fly ash |
  |   | d) Diatomaceous earth |

4) | At equivalent measured slump, concrete containing fly ash as a partial replacement for cement will usually have____?____ compared to concrete with cement only. |
  |   | a) a reduced water demand |
  |   | b) an increased water demand |
  |   | c) about the same water demand |

5) | Which of the following properties assist in the compaction and increased response to vibratory energy in concretes containing fly ash as a constituent? |
  |   | a) Fineness |
  |   | b) Void-filling ability |
 |   | c) Spherical particle shape |
  |   | d) All of the above |

6) | Using 28 day compressive strengths for comparison, over time, plain portland cement concrete generally gains about 30% additional strength, whereas portland cement/fly ash concrete can gain ___?___ additional strength. |
  |   | a) only about 20% |
  |   | b) between 30% and 40% |
  |   | c) between 40% and 50% |  |   | d) more than 50% |

7) | Concrete containing ground granulated blast-furnace slag (GGBFS) dosages greater than ___?___ by mass of cementitious material, have demonstrated an improvement in the resistance to sulfate attack, as well as suppression of alkali-aggregate expansion. |
  |   | a) 25% |
  |   | b) 35% |
  |   | c) 45% |
  |   | d) 55% |

8) | Cement is aninherently variable material and cements supplied from the same mill can have different characteristics from lot to lot. The most important property affected by variability is ____?____. |
  |   | a) water demand |
  |   | b) durability |
  |   | c) strength |
  |   | d) setting time |

9) | Fly ash can have numerous effects on fresh or plastic concrete including improved workability,decreased bleeding, reduced heat evolution and ____?____. |
  |   | a) shortened time of set |
  |   | b) reduced segregation |
  |   | c) increased rate of early strength gain |
  |   | d) reduced ability to consolidate in forms |

10) | Silica fume, a very reactive pozzolanic material, is a by-product of the silicon and ferrosilicon metal manufacturing processes. Silica fume is typicallyused in quantities ranging from ____?____ of the mass of cementitious material. |
  |   | a) 3 to 6% |
  |   | b) 7 to 12% |
  |   | c) 13 to 17% |
  |   | d) 18 to 22% |

Examen 2
1) | A hydraulic cement is defined as a cement that sets and hardens by a ___?___ and is capable of doing so under water. |
  |   | a) drying process |
  |   | b) chemical reaction with air |
  |   | c)chemical reaction with water |
  |   | d) sedimentation process |

2) | Selection of raw materials for the manufacture of portland cement is critical to producing a high-quality product. Which of the following materials is the most common source of lime (CaO), primarily available in the form of calcium carbonate? |
  |   | a) Limestone |
  |   | b) Clay |
  |   | c) Iron bearing...
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