Textbook  Assignment: “Concrete A S S I G N M E N T  6 and  Masonry.” Pages 7-1 through 7-34. 6-1. Concrete is a synthetic construction 6-2. 6-3. 6-4. material made by properly mixing together which of the following ingredients? 1. Water and cement only 2. Water,    cement,    and sand only 3. Water,    cement,    and gravel only 4. Water,    cement,  sand,  and  gravel or crushed stone What is the name of the chemical reaction responsible for the hardening of concrete? 1. Dehydration 2. Hydration 3. Oxidation 4. Deoxidation The chemical reaction that causes concrete to harden occurs between which of the following ingredients? 1. Cement and sand 2. Cement  and  gravel 3. Cement and water 4. Gravel and sand What  factor  controls  the  strength, durability,    and  watertightness  of concrete? 1. The amount of sand 2. The size and shape of the coarse aggregate 3. The proportion of sand to gravel 4. The proportion of water to cement 6-5. The tensile strength of concrete, in comparison  to  compressive  strength, is 1. higher 2. lower 3. approximately the same 6-6. To ensure that concrete is watertight as possible, you should take  which  of  the  following  actions? 1. Add more water 2. Add less water 3. Use only the amount of water required to attain the necessary workability 4. Add more sand to fill any voids 6-7. 6-8. 6-9. 6-10. 6-11. The extent to which concrete resists deterioration caused by exposure to service conditions is called 1. strength 2. compressibility 3. flexibility 4. durability Which of the following materials are placed in concrete to produce reinforced   concrete? 1. Steel  bars 2. Steels  rods 3. Steel strands, wire, and welded wire mesh 4. All of the above What reinforced concrete structural member supports and distributes building loads to the ground? 1. Plain  slab 2. Footing 3. Beam 4. column In  addition  to  the  principal reinforcement,    what  other  steel reinforcing is used in tied columns? 1. 2. 3. 4. The Vertical reinforcing Lateral  ties Spiral reinforcing Mats diameter of reinforcing bars increase from one size to the next by  what  increment? 1. 1/16 in 2. 1/8   in 3. 1/4   in 4. 3/8   in 6-12. Where,    if  anywhere,    in a simple beam (a beam resting freely on two supports near its ends) is there NO stress? 1. Top 2. Bottom 3. Exact  center 4. Nowhere;    all areas have some stress 37