Term
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Definition
A) cement
B) water
C) aggregates |
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Term
| The rules for making good-quality concrete: |
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Definition
-use proper ingredients
- proportion ingredients correctly
- measure ingredients accurately
- mix ingredients thoroughly |
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Term
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Definition
| silica, lime, iron, and alumina |
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Term
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Definition
| Will make up to 60 to 80percent of concrete by volume |
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Term
| AGGREGATES are divided into two types: |
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Definition
1) FINE AGGREGATES: particles are smaller than 6.4mm (0.25in) -usually sand
2) COARSE AGGREGATES : particles are larger than 6.4mm (0.25 in) |
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Term
| The principle factor affecting the strength of the concrete is |
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Definition
| water – cement ratio and the adequacy of curing |
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Term
| STRENGTH in concrete measured in |
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Definition
| pounds per square inch (psi) |
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Term
| Compressive strength is measured from a sample mix |
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Definition
| that has been cast into a standard 6 inch diameter by 12 inch high cylinder, allowed to cure for 28 days, then broken using a lab testing machine. |
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Term
| DURABILITY – is the ability of concrete to |
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Definition
| resist weathering action, chemical attack, abrasion and the other condition of service |
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Term
| Factors affecting durability are: |
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Definition
Freezing and thawing of water in concrete
The amount of ANTRAINED AIR in the concrete
The selection of aggregates
Degree of air drying before freezing
SCALING is the most common sign the concrete is not durable. |
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Term
| one of the most important steps in concrete work. |
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Definition
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Term
| After exposed surfaces of concrete have hardened sufficiently to resist marring ,they should be cured by |
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Definition
| sprinkling or covering with water or by using moisture-retaining materials such as: waterproof paper , plastic sheets , wet burlap or sand. |
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Term
| In cold weather drying concrete must not be allowed to |
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Definition
freeze.
kept warm during the curing process using insulation such as:
-insulated tarp
- straw
- burlap material |
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Term
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Definition
| ADMIXTURES-minerals or chemicals ingredients added to the concrete mix in order to add special properties |
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Term
| ENTRAINED AIR – is an admixture witch |
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Definition
| evenly dispersed form of microscopic bubbles(less than four thousandths of an inch) of air throughout the concrete. |
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Term
| The performance of concrete is related to |
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Definition
| workmanship, mix proportions, aggregate characteristics and amount of cement, presence or absence of entrained air and adequacy of curing. |
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Term
| Good quality concrete should be |
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Definition
| workable, tolerant of some misuse ,strong enough to support supplied loads and durable. |
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Term
| WORKABILITY –is the ease with witch |
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Definition
| freshly mixed concrete can be place, compacted and finished with no separation or segregation of the components. |
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Term
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Definition
1) Welded wire mesh
2) Expanded metal mesh
3) Smooth steel bars
4) Deformed steel bars |
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Term
| EPOXY COATED REBARS-prevent rust______in colour |
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Definition
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Term
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Definition
1) Correct size and shape
2) Substantial enough to retain shape when filled
3) Rigid – won’t move or change when used
4) Tight
5) Easily removed
6) Cost effective |
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Term
| Skin protection –three factors cause skin problems: |
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Definition
Cement is alkaline therefore caustic it will burn
Cement is” hygroscopic” it absorbs moisture therefore it will dry out your skin
Sand in the mix is abrasive |
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Term
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Definition
- Waterproof gloves, long sleeve shirts, long pants
Rubber boots
clean clothes
shower |
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Term
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Definition
Rinse out clothing
Wash out eyes or skin
Skin creams skin irritation
Persistent or severe discomfort ---SEE A DOCTOR |
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Term
| METHODS OF PLACING CONCTERE UNDERWATER: |
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Definition
BAGWORK
TREMIE
PLACING CONCRETE IN FORM WORK |
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