Copyright Goodheart-Willcox Co., Inc. Chapter 18 Concrete Flatwork and Formed Shapes 407 13. When may forms be removed? 14. How is air-entrained concrete fi nished differently than normal concrete? 15. What is the most important consideration in curing concrete properly? 16. At what temperature does hydration stop completely? 17. The most common way to protect concrete against low temperatures during the curing process is to ______ it. 18. Why should concrete not be placed during hot, dry, windy weather? 19. List three things that can be done to reduce the effect of hot weather on placing and curing concrete. 20. What are the three basic types of joints frequently used in concrete construction? 21. What is the purpose of isolation (expansion) joints? 22. Identify three decorative and special fi nishes that are used on concrete. 23. In addition to providing an attractive fi nish, what are three other attributes of exposed aggregate surfaces? 24. When producing an exposed aggregate fi nish using the seeding method, the level of the concrete surface is kept about ______ lower than the forms. 25. What three methods are generally used to apply a geometric pattern to a concrete slab? 26. List the four basic cast-in-place concrete roof and fl oor structural systems. 27. Pan joist roof construction is a one-way structural system in which a ribbed slab is formed with ______. 28. ______ construction is the process of casting concrete walls in a horizontal position on-site or other locations and lifting them from the casting position or truck to their fi nal location in the building. 29. In a tilt-up concrete panel, the thickness is usually determined by a quantity called the ______ ratio. 30. ______ footings are generally for tilt-up buildings. 31. Identify the three most common designs of prestressed panels. Activities 1. (TECH) Investigate trends in decorative concrete. Examples include glow-in-the-dark concrete, acid-stained concrete, and metallic concrete. Prepare a visual presentation that illustrates applications for several types of decorative concrete. 2. (MATH) Determine the amount of concrete needed to place a driveway that is 5″ thick, 24′ wide, and 36′ long. Round up the answer to the closest 1/4 cu yd of concrete. One cu yd is 3′ × 3′ × 3′.