This document discusses building materials and concrete properties. It describes common building materials like cement, sand, aggregates and their annual consumption in India. It then covers properties of fresh concrete like workability, setting times and how admixtures can affect these. Methods for concreting in different temperatures are presented. The importance of the water-cement ratio is highlighted. Hydration products that form when cement hydrates are defined. Concepts like capillary voids, air voids and the gel-to-space ratio are explained in relation to concrete strength.

2. Building Materials
Basic Building Material
● Cement
● Sand
● Fine Aggregate
● Coarse Aggregate
● Steel
● Tiles
● Glass
● Insulative Materials (Roof top, Walls etc.)

3. Annual consumption and associated embodied energy with their production
Raw Material Consumption

4. Annual Indian Material Consumption
Type of
Material
Annual Consumption Raw materials Energy
Burnt Clay
Bricks
150 × 109 nos. Fertile soil (500 ×
106 tonnes)
600 × 106 GJ
Cement 187 × 106 tonnes Lime stone,
gypsum, oxides
650 × 106 GJ
Structural
Steel
45 × 106 tonnes Iron ore, lime
stone
1800 × 106 GJ
Coarse
Aggregates
250 × 106 m3 Granite/basalt rock 30 × 106 GJ
Fine
Aggregates
350 × 106 m3 River sand/rocks 75 × 106 GJ

5. Concrete
Materials required?

6. Properties of Fresh Concrete
● Mixability
● Workability
● Homogenate
● Finishability
● Transportability
● Curable

7. Workability
Concrete should have certain workability
➢ Slump Test
➢ Compaction Factor Test
➢ Vee Bee Test
In absence of suitable workability
➢ Loss of homogeneity
➢ Disintegrate
○ Segregation and Bleeding
○ Setting of concrete

8. ● As the number of floor
increases
● Time for pouring the mix
increases
● Concrete starts to set
● Hence, concrete should be
placed before it loses its
workability.
● Initial Setting Time (IST)
● Final Setting Time (FST)
● Experimental Method - Vicat’s
Apparatus

9. Initial Setting Time (IST)
➢ All the work,
○ placing
○ moulding/remoulding
Should be done within IST.
After that concrete losses its moldability.

10. Final Setting Time
Give definition.

11. Role of Admixtures
When IST/FST needs to be increased or decreased.
➢ Retarders - Increases IST/FST
➢ Accelerators - Speeds up the process of hydration and helps in
achieving early IST/FST
➢ Plasticizers - maintains plasticity of mix.
○ Plasticisers - Low range water reducing agents
○ Super Plasticisers - High range water reducing agents
➢ Air entraining agents

12. Concreting Method
● Upto 40 °C - Normal methods of concreting is used.
● Above 40 °C - Special methods of concreting is adopted.
Special Methods -
➢ Hot weather concreting
○ Problem faced - shrinkage of concrete mix due to evaporation of water which leads to
development of cracks.
➢ Cold weather concreting - Temperature below 10 °C
○ Problem faced - Retardation of setting of concrete takes place.

13. Importance of water to cement (w/c) ratio
● IST = w/c = Free water cement (FWC) ratio

14. Hydration Products
1. Calcium silicate hydrate (CSH) -
a. 50 to 60% of the volume of voids in the completely hydrated cement paste.
b. And this is responsible for the development of the strength of concrete.
2. Calcium hydroxide C(OH)2
a. C(OH)2 crystals are formed which is called as portlandite.
b. Its percentage is 25% in the vol. Of voids of hydrated cement.
c. This forms large crystals during hydration.
d. It does not contribute much in strength of concrete, since it is available in lesser
quantity.
3. Calcium Sulpho Alumino Hydrate ((3CaO•Al2 O3 •3CaSO4 •32H2O)
a. Also, known as ettringite (in crystal form).
b. This occupies 15-20% in total volume of the hydrated cement paste and therefore
plays a minor role in developing micro-structure in a cement paste.
4. Unhydrated cement paste -
a. It is contributed by the clinker grains which remain chemically uncombined.
b. Also, responsible for the unsoundness of the concrete.
5. Capillary Voids -
a. It is represents the space that is not being filled by the solid constituents of hydrated
cement paste.

15. Capillary Voids
● In a well hydrated low water cement paste the capillary voids will be
ranging from 10-50 nm.
● The capillary may be as large as 3-5 μm.
● The capillary voids larger than 50nm are called as macro pores, which
are responsible to influence upon the strength and impermeability.
● Whereas, capillary voids smaller than 50nm, they are referred to as
micro pores, it is responsible for influencing the drying shrinkage or the
creep of concrete.

16. Air voids
● Air voids are spherical.
● A small amount of air is usually get entrapped in the cement paste
during the concrete mixing.
● The best way to eliminate air voids is
○ Compaction
○ Reducing w/c ratio,
○ gel/space ratio,
○ Increasing the degree of compaction.
● 1% of air voids = reduces the strength of concrete of by 6%.
● Air entraining agents - favourable to concrete

17. Gel to Space ratio
● The gel/space ratio is the ratio of solid products of hydration to the
space available for these hydration products.
● In other words, it is a measure of capillary pore space.
● Before hydration, this space is occupied by mixing water, after hydration
the space is the sum of the hydrated cement paste and the remaining
capillary pore space.
x= Volume of gel (including gel pores)
Volume of gel + Volume of capillary pores

18. Strength calculation using Gel/Space ratio
Theoretical strength:
G/S = 0.657 C
0.319 C+ W0’

19. Example:
Calculate the Gel to Space ratio and strength of a sample concrete or mortar
made with 500 gm of cement for w/c = 0.5.
Assume a. Case I - Full Hydration
b. Case II - 60% Hydration

20. Global Solid waste generation
Description Waste Type Waste production
(in billion tonnes)
Global Industrial waste 11 × 109
Municipal solid wastes
(MSW)
1.6 × 109
Total 12.6 × 109
Asia Total Solid wastes 4.4 × 109
Municipal solid wastes
(MSW)
0.790 × 109