diy CONCRETE

Basement floors CLICK HERE FOR HOW TO PAGE basement floors

BLUEPRINT-TO-CONCRETE

slabs 25mpa exterior 30 mpa

- min. 75 thick

-slope to drain

-complete installation of sewer and other subsurface work before pouring

-base of 100 crushed rock  (vapour and soil gas) protection

- a layer of polyethylene .15 lapped 100 or “S” roll roofing

-bond breaker between slab and walls and columns (double layer tar paper)

-air entrained should use magnesium floats

-once water sheen has disappeared trowel and edge - don’t over work causes dusting

-proper control jointing 4.5 to 6 meters in either direction, and at columns and changes of widths of slab,

-control joint cuts should be 1/4 the thickness of the slab

-cure for five to seven days ponding, wet sacking etc. if using a curing membrane ensure that it is compatible with any floor finishes

-slabs on grades should be 200 above finish grades

-water repellent rigid insulation around perimeter

- slab reinforced with 10m rebar at 600 centres both ways

blueprint-to-concrete  STAIRS

Repairing concrete: CLICK FOR HOW TO concrete sacking

blueprint-to-concrete FORMS   CONCRETE-FORMS

Stamp finish

blueprint-to-concrete finish

slab

-screed to level

-float..  to bring cream up and aggregate down - edge to round corners

- float, trowel, smooth hard finish, edge, trowel

blueprint-to-concrete finishing

bull float

-angle bull float to handle is about 30°

-push down on handle for push stroke..  pull up on handle for pull stroke

-the leading edge of bull float should be raised slightly above concrete surface so it rides not ploughs the concrete

-give the handle a shake as you go it causes the concrete to settle

-work concrete until relatively smooth

-next large float is a “darby” a large hand float

-once concrete is relatively smooth you can run the fresno or a steel trowel over the surface... wait for water to settle and trowel again.. do not overwork wet concrete...but once surface water is gone don't be scared to use the steel trowel as many times as you want

blueprint-to-concrete finish

You can use the groover to cut your grooves specially for sidewalks and driveways

...for slabs, you can use a circular saw with a concrete blade... cut it as soon as you can walk on it without scarring it..

set the blade to about 3/4 inch ad run the saw down a straight edge

blueprint-to-concrete finish

floating, edging

strike off, bull float, edger or/and groover, float, wait until surface water is gone and trowel, edge, and groove.. progressively smaller trowels

(knee board and second float to support weight)

blueprint-to-concrete finish

monolithic

pouring as a unit at one time often footings and walls

blueprint-to-concrete finish

screed

the guides that support the strike off bar

attached to stakes at the proper elevation

-screed board is also the give and take strip between slab and wood foundation on “PWF”

blueprint-to-concrete finish

striking off

pull strike off board across screeds moving back an forth for a smooth surface, bull float, trowel, strike bar, mag float, edger, groover, power trowel

blueprint-to-concrete finish
trowelling

after floating once surface water has disappeared use a steel trowel

here I am power troweling.. push down onthe handle in the direction you want power trowel to move...

Adjust angle of power trowel so the more you trowel the less steel touches the surface

Start power troweling when the concrete will hold your weight.. you may sink about a quarter inch when you walk on it

When you start troweling full blade should touch concrete

Keep troweling until you have a very smooth surface

blueprint-to-concrete finish walls

vibrating and placing

- small vibrator 15,000

- 5 to 15 seconds in concrete watch for bubble to stop, shiny surface

- dip at about 1 and 1/2 radius of action

-150 into old layer

-thin forms external vibrators 1 to 2 minutes

- lifts from 1000 to 1200 deep

-stiff mix must be vibrated a large slump may not need vibration

-over vibration causes segregation

- metal chutes 2:1  or 3:1 slopes

-squeeze pressure pump uses vacuum

- concrete can be pumped up to 150m

-conveyer use a down pipe  conveyers can cause segregation

-a window in the form should be used if concrete drops more than 1200 or a reducer hose lowered into wall

- slabs beams and girders are filled first then slab

Finishing

waterproofing

-foundation walls - damp proofed with a layer of asphalt from footing to finished grade

-poor soil drainage or water table high ..  roofing felt applied over asphalt emulsion ..  lapped like shingles two three layers over lapped 100 to 150 hot tar mopped on between each layer

-back fill  once wall is supported or concrete has aged for 14 to 28 days

-where the back filled material is going to carry a slab or sidewalk it must be compacted in 200 to 300 lifts

Floor

finishes

terrazzo marble chips embedded in top of a concrete slab floor is ground and polished for a marble like finish

Floor

reshore

-reshores for at least three stories when moving at one floor per week

-shores and reshores should be directly above each other

-remove and reshore one at a time

-reshore under flat slabs centred between columns

-decentring means removal of reshores

- engineered plans

Cutting

Plywood radius

Use a radius stick nailed to plywood and attached to saw plate

Cutting

Plywood rip guide for 12 to 24 inch cuts

Steel square, a two by slotted to accept one side of square as a rip guide to run along side of plywood,  make slider for other tongue of square that fits rip guide off your circular saw

Layout

Layout square… with large wooden

square

Take: a steel square, two pieces of straight  edge lumber, slot lumber down middle with circular saw, steel square will tap in snug to these slots : voila a large square

Layout

Layout arcs with wooden square

Make a Square wooden guide, and a stick , mark the rise and then the run on the stick put a nail in either end of the stick at these marks …… these nails will ride on the wood square…now drill a hole and put a pencil through the stick where the rise and run meet… lay stick on square push flat along one side… using nails as guides push stick until flat on other side the scribed line is your arc

layout

Layout irregular shapes with tick stick

Tick stick … for irregular shaped filler pieces…  you need sharpened tick stick  and plywood scrap piece… put tick stick to corners,  lay out on plywood scrap, use stick to mark straight lines and slash marks for distance number each one, lay plywood scrap on top of piece to be cut, use tick stick to layout cutting points.. join points and cut

blueprint-to-concrete Floor

suspended slab

- typical scaffold leg holds 10,000 lb.

-aluma stringers must be centred on heads  must join at centre of head

-legs must be with in 12 of plumb in 3000

-form work must be wedged to building

-beams and girders must be filled first

-slopes must be filled from bottom to top

-safe working loads .. rule of thumb.. .of aluma joist 1200 span 1200 kg or 2400 lb., 1800 span  600 kg or 1200 lb., 2400 span 225 kg or 450 LB per foot

-safe working load of stringers 1200 span 3000 lb. .. .1800 span 2000 lb.. .2400 span 1000 lb.

#1 post shore closed 9000 open 5000

#2 post shore closed 8000 open 5000

#3 post shore closed 7500 open 4500

#4 post shore closed 4500 open 2500

-Always wedge at slopes re heads and feet

blueprint-to-concrete footings

columns

-single storey house column footings 640 x 640 x100

-two storey house 870 x 870 by 100

-pipes under footings should be backfilled with concrete

-columns should be seperated from slab casting with a bond breaker such as poly

-wood columns need to be treated and have a moisture barrier between concrete and wood

- this footing uses a cloth membrane as the form walls.. it worked great

Forms

water stop

-made from neoprene rubber

Forms

forms all about forming

wood shores

-single post

-“Ellis” double adjustable post

-“T” head single post

-double post with X braces

blueprint-to-concrete Formulas

battered wall

average thickness of wall times length times height

Formula

centerline

wall center line of a square, rectangle, L or T shaped building (length plus width times two minus four wall thickness)

Formula

Radius from rise of chord

Radius = (rise squared plus run squared) divided by 2 times the rise

Rise being the distance from chord to arc and the run being 1/2 the chord

Formula

Chord for radius wall

Laying out an arc from a chord

Note:

-distance from chord to diameter is constant and the run of your similar triangle

-the radius is your rake

-your rise are equal segments marked out on your diameter

-the difference between your rake and run is the rise of the chord for that given point

- make a diagram draw in your right triangles, diameter, and chord formula becomes apparent

Formula

circle

-area of a circle pi*r squared

-area of circle is .786 of its square

-tangents forming a square about a circle are the same length as the circle’s diameter

-chords forming a square in a circle are 1.4142 times the radius

-diagonal of a square is 1.4142 times one side

-cone 1/3 height times base area

Formula

girders and beams

subtract slab thickness from the beam sizes when ordering concrete  .. . and when building beams

Formula  

octagon

side of an octagon is found by dividing the side of a square by 2.414 ..  the radius  or 1/2 a squares diagonal set on the squares corner points and arced across the sides mark out an octagon. a circle’s 360 ° divided by the number of corners of a polygon give the angles of the polygon .. . 90-180/# of polygon sides = the other angle of the polygon

Formula

volume cone, pyramid and frustum of

v = H/6(ab +(4am)+at)

Joints

expansion joints

use give and take strips between slab on grade and walls and columns

-used any where there is old concrete meeting new concrete that are subject to different movements

Placement

curing

- moisture and heat

-temperature ideal 10 to 15C

-excessive evaporation causes shrinkage and cracking

-do not stain green concrete when curing with sacks

-sprinkling  when not constant can cause dry out and crazing

 and cracking

-two coat curing should be applied at 90 degrees

-3 days 50% 7 days 70%

blueprint-to-concrete Precast

order of assembly

-assembly sequence of pre cast buildings must be given constant attention once materials are ready the crane should be in constant use

-precast often welded in place also grouted and bolt

-backing rod between pieces

-t joists roof or floor coated with concrete topping

-two stage joint

-cables used for temporary support

blueprint-to-concrete Rebar

columns

- form adjusting braces two ways

- steel banding

- avoid twisting the columns by alternating the tension on form adjusters turn buckles

rebar for columns called zones

Rebar

coverage

-beams and columns rebar not exposed to weather, minimum cover 40 for 35M exposed 50

-minimum cover for stirups ties and spirals 30 exposed 40

-structural slabs walls and joists not exposed 20 over 20M exposed 30

-structural shells 15M not exposed cover 15 exposed coverage 30

-footings cast on earth 75

for larger diameter bars 1.5  times bars diameter but no more than 60

maximum aggregate size must be no greater than 1.4 times the rebar seperation

Rebar

curtains

re bar for walls are called wall curtains

-temperature bars are extra rebar.. . for walls of different heights being poured monolithically ..   drying concrete shrinks .. . the two walls will shrink at different rates .. the extra rebar prevents cracking

Rebar

post tensioning

is done after cast in place concrete is poured..  tendons are placed in concrete ..  when concrete has cured the cables are tightened compressing the slab and giving it extra strength against tensile loading  . the tendons are steel cables encased in metal or plastic sleeves anchour points are ductile iron and cables are held by split wedges and cones..  concrete usually rises as post tensioning is applied .. . cables in hollow tubes are grouted into place

Rebar

pre- stressing

prestressing concrete puts the concrete into compression which strengthens it for tensile stresses..  1/3 the steel is required

Rebar

pre- tensioning

is done in factory concrete before it is shipped to job site, use steel cables called tendons  with the tension applied before concrete is poured..  after concrete has set the end fasteners are released transferring the forces internally pre stressed concrete is said to be in a pre compression state

- only 1/3 of the steel needed

Rebar

sizes

size is indicative of the diameter before roughening

Rebar

types

#40 -40000 lb.

#60 -60000 lb.

-steel rebar has the same thermal expansion as concrete

-dowels are usually inserted 24 times their diameter

Rebar

verticals

-dowels are usually inserted 24 times their diameter

Repair

mortar

-use a patching mortar

- clean surface

-wet surface

- surface repairs: mortar  mixed to paste a slump of 50

-brushed on

- trowelled off

-partially dried and sacked

-deep repairs: mortar mixed fairly dry and put on in layers drying each layer completely

-sides of patch area chiseled inwards

-some patches will need form work

-grouting and sack rubbing are done from top to bottom

- no aggregate to be bigger than 1/2 the depth of the repair

Slabs

false work

soffits and scaffolding used on suspended slabs

Slabs

flat plate slab

flat slab, columns

Slabs

flat slab

4 inches thick, dropped panel, column capital

Slabs

joist system

tapered end or fish tail,  floor slab minimum 2”, girders, rectangular  or round columns

Slabs

slab band

floor slab, slab bands, columns

Slabs

slab on grade

- sometimes grade beams

- dense base then 150 coarse gravel

- then polyethylene .15 under slab and  up wall or poly under slab and 25 sand cushion between slab and footing or premoulded joint filler between slab and wall or a cast in place reglet at top of slab with a sealed waterproof membrane

-usually rebar

-isolation joints every six meters isolated from walls with fibre board

- 8 hours for slab sides to set

-

Slabs

two way ribbed

column with capital, dropped panel ribs or joists, coffers  or deep recesses

blueprint-to-concrete Strength

mixing temperature and curing

 -ideal 10C° to 16 C°

-minimum 5C° for three days

-must be maintained at 10°C for 72 hours

-hot weather slabs should be kept moist for seven days

-rapid surface evapouration due to hot weather causes the slab to crack

-concrete mixing is effected by heat of aggregate, easiest to cool is water, warm mixing water can cause a flash set

- concrete should be placed within 11/2 hours

in hot weather, with heavy vehicle traffic (expected delays) water is sometimes mixed into concrete enroute

- in hot weather Forms should be loosened ASAP, in cold weather ALAP

- propane heaters in enclosed spaces cause curing concrete to dust

Strength

aggregates

-round or cubic, clean and strong, fines less than 5 -coarse 5 to 112 - make up 60 to 80 % of concrete, size of aggregate should not be larger than 1/5th minimum dimension, or 1/3 the slab or 3/4 of the clear space between rebar

Strength

air entrainment

-makes a stronger concrete more durable to weathering

-7% air is a normal entrainment

Strength

coatings

curing  spray on membranes

Strength

concrete topping treatments

-curing compounds  .. . membranes chemicals , waxes, protect from early drying

-sealers cure and seal from dusting

-protective treatments .. . from acids, salts, oils, distillates, fats, beer ,milk, vinegar, etc.

-chemical hardeners .. .hard wearing surface

-metal or aggregate hardeners heavy wear surface

-bond breakers between layers re tilt up

-epoxies and adhesives create bonds between old and new concrete

-pigments coloring

Strength

ingredients

- cement: calcium, aluminum oxide, ferrous oxide, silica oxide .. . sets through hydration

Concrete numbers are all variables

-Concrete: 60 t0 80% aggregate , water to  cement ratio 1:2 less water makes a more impervious concrete, entrained air, plasticizers,

-good large aggregate should be clean, hard, strong, cubical over 5 mm in size

-the water to cement ratio is based on kg weights for every 1 kg of water you want 2 kg of cement

(-if it is based on volumes the ratio is one to one one litre of water to one litre of cement)

-fine aggregate is based on the weight of concrete for cubic metre and is 29%

-course aggregate based on the weight of concrete for cubic meter is 52%

-fines should be under 5  mm

-slump is measured using a 100-200-300 slump cone

-low slump is tied to stronger concrete 70 is an example of low slump

-high slump 125 pump concrete should also have 10 to 15% more cement for pumping and aggregates should be round and smooth

blueprint-to-concrete  strength

mpa

-compressive strength of concrete measured in mega pascals

-25 to 30 mpa is very good concrete

-15 mpa minimum for walls, interior slabs on ground (slumps 100), footings and house foundations slump must not exceed 150

- 25 mpa minimum for garage floors sidewalks, concrete stairs 5 to 8% air entrainment slump must not exceed

-garage floors150mm crushed rock or gravel and 75 concrete, foundation walls 150 thick and 150 above grade

Strength

other types

shotcrete for wall reinforcement applied by pneumatic gun

- cementation with liquid grout used under pressure to shore foundations, .. . making rock faces water tight .. . under steel columns under machinery .. metallic aggregates sometimes added to increase compression strength when the high water ratio has weakened.. . with liquid grout  water proof forming is needed, air holes  to allow air to escape are called grout holes

- where a stronger grout is needed dry packing can be used

-mortar is a mixture sand, water, cement  used for bonding in masonry construction and for patching and sacking concrete

-fiberglass reinforced concrete: tanks, pipes boat hulls

-white cement blended for its white color for stucco, decorative concrete

-blended hydraulic cement uses blast furnace slag or pozzolan it sets slower at a lower heat than #10, the pozzolan improves hardness of concrete

-waterproof concrete is made by adding a small amount of stearate to clinker before grinding

-plastic cement used for making mortar, stucco, it is #10 or #20 with a plasticizer

-expansive cement used to fill holes..  expands as it dries

Strength

paving

-slip Forms can layout large highways fast and economically, skid resistant, air entrainment  protects from chemical deicers and from freeze thaw damage

-used for railroads, re: tunnels, bridges, ties

-soil cement a mixture of soil and cement Forms a good hard surface for parking lots, roads and streets covered with a layer of bituminous

Types 10

Types 20

Types  30

Types  40

Types  50

Types

additives or admixtures

-retardants slow down setting time ..  hot weather

-plasticizers increase flow reduce need for vibration

-superplasticizers more expensive than water reducing agents  ..  produce a non vibrating concrete  ..  also speed up setting times

-accelerators speed up setting time

-air entrainment increases strength and protects from weathering

- cold weather  ..   calcium chloride ..  an accelerator can damage rebar should never exceed 2% per volume

-work ability agents example air entrainment increase the workability increase the slump

-damp proofing an initial water cement ratio of less than 50% well cured will give a watertight finish ..  and reduced water permeability additives can be added

-bonding agents .. . epoxies

-grouting agents fill cracks and joints

-gas forming agents cause concrete to expand as it cures

Types

aluminous

concrete made from high alumina cement reaches 28 day strength of portland cement in one day

-in 28 days its crushing strength is twice that of portland concrete

Types

grout

is packed between the concrete base and the shimmed up  steel column or machine plates

Types

hydraulic mortar

is used to patch leaking walls

Types

mortar

-used to stucco or patch concrete has no large aggregates

Types

non vibrating

Types

plaino

self leveling gypsum -- a mixture that finds its own level, is raked to spread evenly and dries to a smooth floor finish ready for carpet or lino, .. . reduces sound and is a fire separator between floors

Walls

damp proofing

-damp proofing is a layer of bituminous  or a sheet of polyethylene .15 seams lapped 100

-water proofing is proofing against hydrostatic pressure a impermeable membrane (two layers of bitumen saturated felt and covered with liquid bitumen

-floors subject to hydrostatic pressure must have a wall membrane sealed to a floor membrane which is sandwiched between two layers of 75 concrete