ACI Concrete FlatACI Concrete Flatwork Finishing Certification Questions And Correct Answers work Finishing Certification Questions And Correct Answers

ACI Concrete Flatwork Finishing Certification Questions And Correct Answers How to reduce excessive bleeding on job site? - ANSWER -Don't add water to the mix How to reduce the chance of scaling? - ANSWER -Air-entrainment Random cracking causes: - ANSWER -Placing slab on uneven surfaces, plastic shrinkage, not deep enough joints, sawing too late, spacing joints too far apart, etc Settlement cracking is likely yo occur when: - ANSWER -Concrete sets slowly When is air-entrained concrete used? - ANSWER -When it will be exposed to freezing and thawing cycles What is a byproduct of cement meeting water? - ANSWER -Heat of hydration (gets hotter) Strength of normal concrete is dependent of: - ANSWER -Water cement ratio What is the most economical way of pouring concrete? - ANSWER -Chute directly off a truck How can delays be avoided when using a boom pump? - ANSWER -By allowing enough room to fit 2 trucks, so one truck is ready while the other is finishing When to use a bull float? - ANSWER -When the FF number is below 20 When to use a highway straightedge? - ANSWER -When the FF number is 20 or above What are hand floats used for? - ANSWER -To start the floating process, to produce a plane level finish, texture finish as well Wood floats: - ANSWER -Best for non-air-entrained and high slump concrete Magnesium float: - ANSWER -For air-entrained and lightweight concrete Hand finishing trowel: - ANSWER -Used in the final stages of finishing, after floating, steel 3-5" wide & 10-20" long Fresnos: - ANSWER -Large, long-handed trowels that look like bull floats. Blade= 5" wide and 24-48" long. Use Fresno when bleed water is evaporated Slab finishing steps: - ANSWER -Pour concrete, screening, floating, edging, jointing, and troweling Dipstick - ANSWER -Measures both floor flatness and levelness When to do F-number testing? - ANSWER -ASAP, preferably within 24 hrs of placement, but no later than 72 hrs The higher the F-number: - ANSWER -The more level the floor The closer to 50: - ANSWER -The more flat & level it'll be When to trowel left to right? - ANSWER -When pulling concrete into a low spot When to trowel right to left? - ANSWER -Pulling concrete into a high spot What is concrete made without coarse aggregate? - ANSWER -Motar or grout What do accelerating admixtures do? - ANSWER -Speed up setting/ hardening time Where are accelerating admixtures useful? - ANSWER -In cold weather What tool to use on granular subleases and sandy soils? - ANSWER -Vibratory plate compactor What tool to use on a clay sublease? - ANSWER -Sheepsfoot roller When specs don't require a concrete slab to come in direct contact with the vapor, the preferred method for reducing slab curling problems is: - ANSWER -Placing a 3" thick layer of compatible sand containing ROCK DUST on the vapor retarder prior to concrete placement How is concrete quantity calculated? - ANSWER -L x W x H / 27 yd^3 10% rule - ANSWER -Move decimal one spot to the left of your calculated number, then add this number to calculated number When striking concrete with a handheld vibrating screed, what should you do? - ANSWER -Strike straight back, must always be enough concrete to fill voids ahead of the screed, avoid low spots. When to use wet screeds? - ANSWER -When FF numbers are above 20. What does rebar do? - ANSWER -Keeps cracks tightly closed Contraction joint rule: - ANSWER -Must be 1/4 the slab thickness What 2 methods can be used in hot weather, when slab curling may have to start after placing but before finishing? - ANSWER -Evaporation retarders and fog sprayers Curling with burlap: - ANSWER -Wrinkle bumps Where to start edging: - ANSWER -2 ft off the corner; avoid starting at the edge Isolation joints should be: - ANSWER -Circular or diamond How is concrete sold? Sold in what units? - ANSWER -By volume in cubic yards or cubic meters Concrete should be completely discharged: - ANSWER -Within 1 1/2 hours Who should attend the pre-construction meeting? - ANSWER -Finisher foreman Type I Concrete - ANSWER -Normal or ordinary use What is type I concrete typically used on? - ANSWER -Slab-on grade, reinforced concrete buildings, and bridges Type II Concrete - ANSWER -Moderate sulfate resistance Where is type II concrete used? - ANSWER -Where moderate sulfate exposure from the soil or groundwater must be resisted Type III Concrete - ANSWER -High early strength Type III Concrete Properties - ANSWER -Similar to Type I, but more finely