Table of Contents
What are chairs and bolsters used for?
Chairs and bolsters are used to: support reinforcing bars in beams and slabs, prior to concrete placement.
What is the name of the support that keeps the rebar at the desired level in the formwork?
A rebar spacer is a device that secures the reinforcing steel or “rebar” in reinforced concrete structures as the rebar is assembled in place prior to the final concrete pour. The spacers are left in place for the pour to keep the reinforcing in place, and become a permanent part of the structure.
Which is not a method of permanently joining precast concrete members in a building?
Which is not a method of permanently joining precast concrete members in a building? Gravity connections, where each member is unconnected to adjacent member(s).
What is the main purpose of the strike off phase of finishing a concrete slab?
Screeding or strikeoff is the process of cutting off excess concrete to bring the top surface of the slab to proper grade.
What are bolsters for concrete?
Provide support for reinforcement when pouring concrete slabs. Slab bolster is used for supporting lower slab steel from slab form.
What is a beam bolster?
Beam bolster is used to support lower beam steel from the slab form.
What is continuous rebar?
A lap is when two pieces of reinforcing bar (rebar) are overlapped to create a continuous line of rebar. The length of the lap varies depend on concrete strength, the rebar grade, size, and spacing. CRSI’s Reinforcement Anchorage and Splices includes tables of required lap splice lengths based on these variables.
What holds rebar off the ground?
Standard Rebar Chairs The most common type of chair simply suspends the rebar off the ground so that it becomes fully embedded in the concrete as it is poured. They are often used on foundation footings, concrete slabs, and other flatwork. The chairs may be made of metal or plastic or other non-corrosive material.
Why concrete must be compacted in the forms to eliminate trapped air?
concrete must be compacted in the forms to eliminate trapped air and to fill completely around the reinforcing steel and into all the corners of the formwork. If concrete has too low a slump, it will be difficult to handle and place in forms, and it will be likely to form voids.
Which of the following is principal function is to provide lateral stability to a steel frame?
Which of the following has the principal function of providing lateral stability to a steel frame? Shear studs are often welded to the top of a steel beam. These studs serve to: bond the beam to the concrete and cause the beam and concrete to act as a single structural unit.
How can the wall panels increase vertical span capacity while minimizing weight?
Wall panels can be ribbed, to increase their vertical span capacity but maximizing weight, or formed into other special shapes.
What is the process for finishing concrete?
HOW TO FINISH CONCRETE Spread the concrete. Use a square shovel or a come-along tool to push and pull the wet concrete into place. Screed the concrete. During this step remove excess concrete and bring the surface of the concrete to proper grade. Float the surface. Edge the slab. Groove in joints. Trowel the surface.
What is the purpose of finishing concrete?
The primary purpose for finishing concrete pavements is to remove any small surface imperfections and seal the surface of the slab.
What are the two stages of finishing the concrete?
Screeding (Step-1) screeding. This is the process of striking off the excess concrete to bring the top surface to proper grade. Floating (Step-2) bull float for finishing concrete. Floating consists in removing the irregularities on the surface of concrete which are left after screeding. Trowelling (Step-3) Trowelling.
What is a slab bolster upper?
The slab bolster upper provides continuous reinforcing bar support for the upper layer of reinforcing steel. It is used to support one layer of steel above another and space them accordingly. The slab bolster upper consists of two runner wire and a continuous top supporting wire connected by evenly spaced legs.
What is a rebar chair?
The 2-1/4in plastic rebar chair is a durable plastic rebar support system that is ideal for concrete applications. The chairs are easy to work with and eliminates the need for wire tying saving time.
How do I calculate how much rebar I need?
To determine the total linear rebar footage required, multiply the number of rebar you calculated for each side by the length measurement. Add those numbers together for the total number of linear feet of rebar you’ll need.
What is a bolster in construction?
Bolsters are commonly used in the construction industry for the support of post-tension cables, rebars, or mesh above a surface. Typically, when such materials are used, they must be supported above the surface when the concrete is poured. These bolsters are used with poured decks.
What is compression lap?
The compression lap splice strength is a combination of the effect of bond and end bearing strength. If the bond capacity is assumed to be governed by a splitting failure of concrete around the bar, the tensile strength of the concrete significantly affects the bond capacity.
What is a hairpin in concrete?
Hairpins are reinforcing bars bent into the shape of the letter “U”. The bars are used to anchor inserts, anchors, or post-tensioning tendons into concrete to prevent the concrete from “blowing out” at a free edge.
