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CONCRETE. Concrete made of three materials. 1. PORTLAND CEMENT lime, silica, and alumina Adding water causes chemical reaction: hydration. Concrete made of three materials. 2. Water Amount of water affects the final strength Too much reduces strength. Concrete made of three materials.
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Concrete made of three materials 1. PORTLAND CEMENT • lime, silica, and alumina • Adding water causes chemical reaction: hydration
Concrete made of three materials 2. Water • Amount of water affects the final strength • Too much reduces strength
Concrete made of three materials 3. Aggregates • Sand or gravel • Improves cement structure
CONCRETE Bonds with aggregates • initial set: 45 minutes • final set: 10 hours • Final cured strength: 28 days
MORTAR • Material used to bond masonry units together • Not structural like concrete
MORTAR • Bonds are just the opposite of concrete: • Higher water-cement ratios bond better
Bricks Cored brick • cheaper
Bricks Bullnose brick • Rounded edge
CONCRETE • Most landscape jobs, 4000 PSIconcrete with 3” slump • Slump is measure of the amount of water in concrete
CONCRETE ACCESS FOR MIXER • Wheelbarrow
CONCRETE ACCESS FOR MIXER • Concrete boom
BASE AND REINFORCEMENT Wiremesh, reduce cracking and strengthen
BASE AND REINFORCEMENT Fibermesh, tiny strands of fiberglass added to mix
FORMS • 2x4 most common • Curved sections using flexible plastic
EXPANSION JOINTS • Absorb expansion of concrete when warm • Between concrete and a permanent object
EXPANSION JOINTS ½” plastic or fiberboard
POUR • Screed in sawing motion to the top of the form
FLOATING • Smoothingsurface • Magnesium, steel or wood float
FLOATING • Kneeboards to reach center
FLOATING Bull floating is the initial float • Compacts concrete, brings up water • Reduces cracking
Pouring Concrete • Forms
Concrete Sidwalk • Base material • 57 Stone
Concrete Sidwalk • Wiremesh
Concrete Sidwalk • Concrete
Concrete Sidwalk • Screed level with forms
Concrete Sidwalk • Bull float
Concrete Sidwalk • Float finish
Concrete Sidwalk • Contraction joint
CONTRACTION JOINTING • 3/8” groove across concrete • Controls cracking as slab dries • Cracks will occur on contraction joints
JOINTING • While concrete still wet • Or cut after dry
JOINTING • Can be part of design
Concrete Sidwalk • Edge
EDGING • Rounds and smoothes the edge • Done while wet • Reduces chipping
CURING • Retains heat and moisture • Cover with plastic sheet • Or spray with membrane compound
CURING • Improves strength and reduces cracking • Slows down drying • Cover a minimum of 24 hours • Ideally 3 to 7 days • Until moisture no longer under plastic
Concrete Sidwalk • Broom finish
Broom Finish • Broom, texture and non-slip
Broom Finish • Broom, perpendicular to traffic
Color Concrete • Dye mixed with concrete or topdressed on surface
Stamping Concrete • Realistic paver or stone patterns • Stamping Concrete Video • About $8 / square foot
Stamping Concrete • Colored release agent: colors and keeps concrete from sticking to stamp