8 . Form finish can be utilized primarily for cast-in-place walls . 9 . Form liners attach to forms and are typically pre-formed . 10 . Sacked finish applies to cast-in-place concrete and requires rubbing the finished concrete surface with raw cement . Sacking is typical of exposed structural concrete construction .
checkerboard alternate pours . Construction joints are placed to define the extent of a given slab pour , e . g . end of day pour , paving type break or delays in concrete placement ( hardened concrete ), and usually conforms to a predefined joint layout . Construction joints should always use steel dowels with Speed Dowel TM tubes to help distribute the load between adjacent slab sections and prevent vertical slab displacement . ACI recommended joint spacing is 16-foot by 16-foot modules ( modules should not exceed 20 feet by 20 feet ).
3 . Isolation joint ( often called expansion joint ) is used to permit movement between vertical and horizontal surfaces , e . g . horizontal slabs against walls , columns , foundations , footings or other points of restraint such as drains , manholes , utility covers , and steps . Isolation joints are normally installed first with a pre-molded joint filler , backer rod and caulking .
RULE 10 CURING
RULE 9 JOINTING
All concrete should be properly cured . Curing consists of maintaining a satisfactory moisture content and temperature in concrete during its early stages so that desired strengths may result without excessive fracturing and breakage .
Architectural concrete must always be jointed . Concrete jointing serves two basic purposes : it controls the location of anticipated random slab cracking and it aids in the esthetic appearance of architectural concrete . There are three basic paving joint types recognized by the ACI :
1 . Contraction joint ( often called control joint , hand-tooled joint , crack control joint ), is a decorative sawcut or tooled joint used to avoid random cracks or provide an esthetic score line pattern . Contraction joints are installed as soon as possible , either tooled while the slab is still plastic or by sawcutting within eight to 24 hours , but should be cut as soon as possible . Delaying sawcutting operations increases the likelihood of random slab cracking . The ideal contraction joint spacing is between eight to 12 feet o . c . e . w . for a four-inch reinforced slab . Cut all contraction joints at least 1 / 4 the depth of the slab .
2 . Construction joint ( often called cold joint or doweled construction joint ) is the most commonly used method for A / B pours or
1 . Begin curing slabs immediately after finishing because slabs can lose moisture and change temperature very quickly . This can lead to surface cracks .
2 . Concrete should be kept continuously moist for at least seven days .
3 . There are several ways to cure concrete : A . Water ponding . B . Sprinkling or fogging with water . C . Virgin mill carpet ( keep damp ). D . Wet burlap or synthetic blankets . E . Waterproof paper . F . Curing compounds .
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