Division 3: Concrete Flashcards by rajah magat

One of the oldest manufactured building materials used as a mortar and plaster by early civilizations

Lime

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The process of mixing quicklime with water is absorbed and heat is energetically evolved

Slaking or hydration

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This may be used one half hour after being made into a putty

Special finishing hydrated lime

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A type of lime which will set under water is

Hydraulic lime

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The densest and hardest gypsum that can be applied with a trowel

Keene’s cement

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Made by mixing slaked lime with pozzolana which hardened under the water

Cement

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Who rediscovered hydraulic cement?

Smeaton, 1756

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Who invented and patented portland cement

Aspdin

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Obtained by finely pulverizing clinker produced by calcining to incipient fusion an intimate and proportioned mixture of argillaceous and calcareous materials

Portland cement

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Components of portland cement
Tricalcium silicate 1/2 volume
Dicalcium silicate 1/4
Tricalcium aluminate 1/10 volume

Yeha

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Each bag of portland cement holds

1 cu. ft weighs 94 lbs

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Type of portland cement used when early removal of formwork is desired or in cold-weather construction

High early strength

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Type of portland cement used in construction of massive concrete structures

Low heat: sulfate resisting

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Quick setting cement

Alumina cement

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Prepared mixtures of portland cement

Masonry cements

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Cements made of natural raw materials

Natural cements

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Type of cement made of lime mortar and pozzolanic material

Pozzolanic cement

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Type of cement made of lime mortar and pozzolanic material

Pozzolanic cement

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Storage of cement should be stored in shed with a wood floor raised about __ from the ground

12”

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Piles should be limited to ___ sacks in height

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The proportioned mixture of cement m, aggregate and water, which when properly proportioned is at first a plastic mass which can be cast or molded into predetermined size or shape

Concrete

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Good quality concrete is obtained through

Careful selection of mayerial
Correct proportioning
Thorough mixing 
Careful transporting and placing 
Proper curing or protection of the concrete

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measuring the consistency of a concrete mix

Slump test

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The amount of water used per bag of cement

Water-cement ratio

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Size of slump test metal cone

Bottom-8” Top-4” Height-12”

Consistency slump of reinforced foundation, walls and footings Max and min

125mm(5”) | 50mm(2”)

Consistency slump of plain footings, caissons and substructure walls Max and min

100mm(4”) | 25mm(1”)

Consistency slump of slabs, beams, thin reinforced walls & bldg columns Max and min

150mm(6”) | 75mm(3”)

The most widely used test for concrete compressive test

Compressive test

To test existing concrete structures by drawing out a core cylinder

Concrete Core test

The strength of a workable concrete mix depends upon the _______

Water-cement ratio

Economy of the mix depends upon the proper proportioning of

Fine and course aggregates

Methods of proportioning concrete includes:

Proportioning by arbitrary proportions. By water-ratio and slump test. By water-ratio, slump and fineness modulus.

Class AA

1:1.5:3 | For concrete under water;retaining walls

Class A

1:2:4 | For slabs, beams, columns, arches walls of 4” thk

Class B

1:2.5:5 | Walls thicker than 4”, footings, steps, reinforced concrete slabs on fill

Class C

1:3:6 | For plant boxes and non critical structures

Class D

1:3.5:7 | For mass concrete works

Sufficient materials are placed at one time to make a convenient size batch of concrete

Batch Mixers

The materials are fed constantly and from which the concrete is discharged in a steady steam

Continuous mixers

The delivery from the mixer to the forms should be fairly continuous and uninterrupted not exceeding ____

30 mins

Concrete should never be allowed to drop freely over ___ for unexposed work and over ___ for exposed work.

5ft and 3 ft.

Reduction in volume of concrete or mortar or plaster caused by a loss of moisture

Drying shrinkage

Reduction in volume of concrete prior to its final set, caused by hydration of the cement paste

Setting shrinkage

Three main factors affecting the hardening

Age or time Temperature Moisture

Used to speed up setting time and to develop earlier strength to reduce length of time for protection.

Accelerators

Used during very hot weather to slow down the hydration of the cement.

Retarders

Manufactured from such as rosin, beef tallow, stereates, foaming agents(soap).

Air-entraining agents

Non metallic colored floor hardener

Flor-Hard

Preferred plywood for form construction

Phenolic board

Most commonly used plastic form

Polystyrene and ABS

Process of eliminating voids other than entrained air within newly placed concrete and ensuring close contact of the concrete

Consolidation

Done by the repeated insertions and withdrawals of a flat spade like tool

Spading

Repeated insertions and withdrawals of a rod

Rodding

Moderately high frequency oscillations of a vibrator

Vibration

Characterized by a low yield, high deformability and moderate viscosity

Self consolidating concrete or self-compacting concrete

Who conceptualized SCC?

Prof. Okamura 1986 Ouchi university, Japan

The separation of course aggregates from the mortar or from water from the ingredients of freshly mixed concrete

Segregation

Separation of an excessively wet or over-vibrated concrete mix

Stratification

Emergence of excess mixing water on the surface of newly placed concrete

Bleeding

Milky deposit containing cement and aggregate fines on the surface of new concrete

Laitance

Voids on a formed concrete surface caused by segregation during placement or by insufficient consolidation

Honeycomb

Chipping or scaling of a hardened concrete or masonry surface

Spalling or scaling

Appearance of numerous hairline cracks occuring in the surface of newly hardened concrete as a result of a rapid drying shrinkage

Crazing

Curing period: | Massive footings

1 day

Curing period: | Cantilever footings

5 days

Curing period: | Slab footings

5 days

Curing period: | Massive walls, 30 cm. thk

1 day

Curing period: | Thin walls less than 30 cm thk

2 days additional 1.5 days per meter

Curing period: | Columns: ratio of height at least diameter up to 4

2 days add 1 day per meter

Curing period: | Slab-3 to 7ft. Spans

5 days add 1/2 day per ft

Curing period: | Slab- over 7 ft. Span

7 days add 1 day per ft

Curing period: | Beams side

3 days

Curing period: Beams and girders Bottom

Up to 14 ft, 14 days add 1 day per ft

Curing period: | Spandrel walls

7 days

Curing period: | Spandrel arches

14 days

Main arches

21 days

Curing period: | RC piles and RC post

Sides- 3 days | Bottom-14 days

The bars may be plain or deformed( with lugs or projections for better bonding to the concrete)

Billet-steel bars or rail-steel bars

Steel bars size

1/8”- 1 1/2” and length 20 or 30 ft

Made of cold drawn steel wire widely used for the reinforcement of concrete slabs and floors

Wire fabric

Fabric consists of a series wires welded together to form a grid pattern.

Welder wire fabric/ woven wire fabric (4”x4”,6x6,8/8) rolls 5 or 6 ft wide, 150,200 and 300 long

This is built up of either single or stranded longitudinal wires with cross wires or bond-wires running diagonally across the fabric.

Triangle mesh wire fabric | 4” on center cross wires 4” or 8” apart

Stretched by pressure until the desired opening or forms are obtained. Can be shaped in diamond, crimp, herringbone and Z-rib

Expanded mesh | E.g. steelcrete

This is a lightweight, expanded structural concrete produced by adding a small amount of metallic aluminum powder to the mixture of portland cement and sand of cinders.

Aerocrete

This is the mixture of sand and cement deposited under high pneumatic pressure with a machine manufactured under the trade name “cement gun”

Gunite

A portland cement concrete to chich a chemical foam is added to generate gases in the process of deposition

Porete

This is processed concrete added with lightweight aggregate.

Haydite

Weighing from 25-60 lbs. per cu.ft is well qualified as a lightweight aggregate when dry and well graded.

Pumice

Composed of stable silicates and is inert and thus durable for use as a lightweight aggregate

Perlite

A micaceous mineral which expands on application of heat to as much as 30 times its original volume.

Vermiculite

Made by treating molten blast furnace slag with controlled quantities of water or steam.

Expanded Slag

Composed of the ash components of the coal along with the various quantities of unburned or partially burned combustible matter.

Cinders

Division 3: Concrete Flashcards

(93 cards)