Building Material BLD62003

Tutorial Presentation

Hwang Wei Li

Andrew Mah Koon Yan

Kong Zhen Chung

Gan Xiao Ying

Lily Then

concrete

Concrete Strength & Workability

Types and

Quality of

Cement

Texture,Typeand

ShapeOf

Aggregate

Curing Conditions

concrete

A mixture between

CEMENT

SAND

AGGREGATE

Types and Quality of Cement

Types of Cement

1. General purpose (Type I) – Ordinary

2. Modified general purpose (Type II)

3. High-early strength (Type III) – Rapid hardening

4. Low-heat of hydration (Type IV) – Low heat

5. Sulphate resisting (Type V)

Types of Cement

1) Aluminous cements

2) White Portland cement

3) Natural cement

4) Lime

5) Gypsum cement

6) Oxychloride cement

7) Masonry cement/Mortar

8) Fly ashes

9) Silica fume (Microsilica)

Quality of Cement

A good quality cement should have the following factors:-

• When you insert your hand in a cement bag, it should give a cool feeling.

• It should be greenish grey in colour.

Quality of Cement

• There should be no lumps or dust in the cement.

• If you throw a small quantity of cement in a bucket of water, the cement should float for a few minutes before it sinks.

• When you take a pinch of cement in your hands and rub between the fingers, it should give a smooth finish.

CuringConditions

• Provide adequate moisture, temperature & time • For freshly cast concrete to achieve desired properties

o Prevents loss of moisture from the concrete

o Maintains favourable temperature for

hydration

o Rapid cooling during the first few days after

placing

o Leaching out by rain and flowing water

Curing Conditions

Main Functions of Curing1. Maintaining mixing water in concrete during the early

hardening process through :-

• Ponding & Immersion

• Spraying & Fogging

• Saturated Wet Coverings

• Left in Place Forms

Main Functions of Curing2. Reducing the loss of mixing water from the surface of the concrete through :-

• Covering concrete with impervious paper or plastic sheets.

• Applying membrane-forming curing compounds.

Main Functions of Curing3. Accelerating strength gain using heat and additional

moisture through :-

• Live steam / Steam curing

• Heating Coils

• Electrical Heated Forms or Pads

• Concrete Blankets

TEXTURE, TYPE, AND SHAPE OF AGGREGATES

DENSE AGGREGATE

LIGHTWEIGHT AGGREGATE

Conclusion