*2.1.3 Fly ash*

Fly ash is extracted from flue gases by means of electrostatic precipitator in dry form. It is a fine material and possesses good pozzolanic property. Fly ash is a by-product of thermal power stations of India and it is of good quality as it contains low sulfur and very low un-burnt carbon. The pozzolanic property of fly ash makes


#### **Table 1.**

*Chemical composition of iron ore tailings.*


**43**

*Geopolymer Bricks Using Iron Ore Tailings, Slag Sand, Ground Granular Blast Furnace Slag…*

**Constituents Percentage (%)** SiO2 30.73 Fe2O3 0.56 Al2O3 16.32 CaO 38.47 MgO 6.41

**Properties Results** Specific gravity 2.65 Water absorption 1% Fineness modulus 3.363

it a reserve for making cement and other ash based products. The specific gravity of fly ash used is 2.17 in the present work. (Please refer to **Table 5** for chemical compo-

Granulated blast furnace slag (GGBS), is obtained by rapidly chilling (quenching) the molten ash from the furnace with the help of water. During this process, the slag gets fragmented and transformed into amorphous granules (glass). This granulated slag is then ground to the desired fineness for producing GGBS. It is one of the greenest construction materials. GGBS replaces something that is produced by a highly energy-intensive process. The specific gravity of GGBS used in this work is 2.61.

Sodium hydroxide is obtained from sodium carbonate which is formerly known as caustic soda. At room temperature, sodium hydroxide exists as a white crystalline odorless solid which absorbs moisture from the air. When dissolved in water or neutralized with acid it liberates substantial heat, which may be sufficient to ignite combustible materials. It is very corrosive. It is generally used as a solid or as 50% solution. Sodium hydroxide is one of the widely used chemical substances in laboratory and in industries. It is also used in the manufacture of other products like paper pulp and various chemical products like plastics, synthetic textiles, geopolymers etc. (Please refer to **Table 7** for the specification of sodium hydroxide, NaOH).

Sodium silicate is usually known as water glass or liquid glass. It is well-known due to its wide commercial and industrial application. It is composed of oxygensilicon polymer backbone lodging water in molecular matrix pores. Sodium silicate products are manufactured as solids or thick liquids, depending on proposed

*DOI: http://dx.doi.org/10.5772/intechopen.81748*

sition of Fly ash used).

*Physical properties of slag sand.*

*Chemical composition of slag sand.*

**Table 3.**

**Table 4.**

*2.1.5 Sodium hydroxide*

*2.1.6 Sodium silicate*

*2.1.4 Ground granulated blast furnace slag (GGBS)*

(Please refer to **Table 6** for the chemical composition of GGBS).

#### **Table 2.**

*Physical properties of iron ore tailings.*

*Geopolymer Bricks Using Iron Ore Tailings, Slag Sand, Ground Granular Blast Furnace Slag… DOI: http://dx.doi.org/10.5772/intechopen.81748*


#### **Table 3.**

*Geopolymers and Other Geosynthetics*

*2.1.2 Slag sand*

*2.1.3 Fly ash*

cyclizing etc. The Iron ore tailing usually contains about 20–30% of iron. Further extraction of iron is too expensive. The composition of the ore and the process of mineral extraction adopted have a direct influence over the composition of the tailings. The iron ore tailings are obtained from Bellary, Karnataka, India, where steel companies are located (Please refer to **Table 1** for the chemical composition and

Similar iron ore tailings are available in other parts of India and world too which

Slag sand, is an eco-friendly building material obtained as a by-product of the industrial process which can replace conventional river sand in the construction of buildings. It caters to the increasing demand and quality requirements of the fine aggregates. Slag sand as an alternative to river sand will protect river banks and save the environment (Please refer to **Table 3** for chemical composition and **Table 4** for

Therefore, replacing river sand with slag sand leads to a better environment and

Fly ash is extracted from flue gases by means of electrostatic precipitator in dry form. It is a fine material and possesses good pozzolanic property. Fly ash is a by-product of thermal power stations of India and it is of good quality as it contains low sulfur and very low un-burnt carbon. The pozzolanic property of fly ash makes

becomes an economically viable solution for the shortage of fine aggregates.

**Constituents Percentage (%)** SiO2 16.05 Fe 44.82 Al2O3 6.34 CaO 1.52 MgO 0.28 MnO 1.20 TiO2 0.38 L.O.I 10.09

**Properties Results** Specific gravity 3.4 Fineness modulus 2.81 Optimum moisture content 13% Bulk density 2.54 Maximum dry density 2.25

**Table 2** for the physical properties of the iron ore tailings used).

have different percentage of iron in the tailings.

the physical properties of slag sand).

**42**

**Table 2.**

**Table 1.**

*Physical properties of iron ore tailings.*

*Chemical composition of iron ore tailings.*

*Chemical composition of slag sand.*


#### **Table 4.**

*Physical properties of slag sand.*

it a reserve for making cement and other ash based products. The specific gravity of fly ash used is 2.17 in the present work. (Please refer to **Table 5** for chemical composition of Fly ash used).

#### *2.1.4 Ground granulated blast furnace slag (GGBS)*

Granulated blast furnace slag (GGBS), is obtained by rapidly chilling (quenching) the molten ash from the furnace with the help of water. During this process, the slag gets fragmented and transformed into amorphous granules (glass). This granulated slag is then ground to the desired fineness for producing GGBS. It is one of the greenest construction materials. GGBS replaces something that is produced by a highly energy-intensive process. The specific gravity of GGBS used in this work is 2.61. (Please refer to **Table 6** for the chemical composition of GGBS).

#### *2.1.5 Sodium hydroxide*

Sodium hydroxide is obtained from sodium carbonate which is formerly known as caustic soda. At room temperature, sodium hydroxide exists as a white crystalline odorless solid which absorbs moisture from the air. When dissolved in water or neutralized with acid it liberates substantial heat, which may be sufficient to ignite combustible materials. It is very corrosive. It is generally used as a solid or as 50% solution. Sodium hydroxide is one of the widely used chemical substances in laboratory and in industries. It is also used in the manufacture of other products like paper pulp and various chemical products like plastics, synthetic textiles, geopolymers etc. (Please refer to **Table 7** for the specification of sodium hydroxide, NaOH).

#### *2.1.6 Sodium silicate*

Sodium silicate is usually known as water glass or liquid glass. It is well-known due to its wide commercial and industrial application. It is composed of oxygensilicon polymer backbone lodging water in molecular matrix pores. Sodium silicate products are manufactured as solids or thick liquids, depending on proposed


#### **Table 5.**

*Chemical composition of fly ash.*


#### **Table 6.**

*Chemical composition of GGBS.*


#### **Table 7.**

*Specifications of sodium hydroxide (NaOH).*

function. Sodium silicate is a versatile, inorganic chemical manufactured by combining different ratios of sand and soda ash at high temperature.

This process gives a variety of products with unique chemistry that are used in many industrial chemistry that are used in many industrial and consumer applications.

#### *2.1.7 Water*

Potable water is used for the manufacturing of geopolymer bricks.

#### **2.2 Mix proportion**

Six different mix proportions shall be considered viz.; GB-1, GB-2, GB-3, GB-4, GB-5 and GB-6. The slag sand shall be mixed with portions of IOT as a partial replacement with the following percentages; 20, 30 and 40% of the total dry mix. Fly ash (15%) and ground granulated blast furnace slag (15%), which are kept constant, all together contribute 30% of the total dry mix. The molarity of the sodium hydroxide solution adopted shall be 8 and 10 M. The alkaline solution shall contribute 10% of the total mix. The optimum moisture content adopted shall be 8%. The Na2SiO3 to NaOH ratio adopted shall be 2.5. Alkaline solution to binder

**45**

*Geopolymer Bricks Using Iron Ore Tailings, Slag Sand, Ground Granular Blast Furnace Slag…*

**Brick ID IOT% Sand% Fly ash% GGBS% Alkaline solution%** GB-1 20 40 15 15 10 (8 M NaOH Soln.)

GB-4 20 40 15 15 10 (10 M NaOH Soln.)

**Quantity of ingredients/stabilizer**

material ratio adopted shall be 0.35. (Please refer to **Table 8** for the mix proportion

'MARDINI' is the advanced version of the mud block press machine developed

at the Department of Civil Engineering/ASTRA, Indian Institute of Science, Bengaluru, India. The size of stabilized mud block manufactured in the machine shall be 230 × 110 × 100 mm. The process of block making involves a series of

*DOI: http://dx.doi.org/10.5772/intechopen.81748*

GB-2 30 30 15 15 GB-3 40 20 15 15

GB-5 30 30 15 15 GB-6 40 20 15 15

including the molarity).

**Table 8.**

**2.3 Process of block making**

*Mix proportions of geopolymer bricks.*

sequential steps as below:

a.Soil preparation

f. Block pressing

b.Alkaline solution preparation

c.Mixing of soil and stabilizer

d.Addition of extra water

e.Weighing of soil in scoop

g.Block ejection and stacking

h.Curing of the block (7, 14 and 28 days)

*Geopolymer Bricks Using Iron Ore Tailings, Slag Sand, Ground Granular Blast Furnace Slag… DOI: http://dx.doi.org/10.5772/intechopen.81748*


### **Table 8.**

*Geopolymers and Other Geosynthetics*

**Table 5.**

**Table 6.**

**Table 7.**

*Chemical composition of fly ash.*

*Chemical composition of GGBS.*

**Specifications of NaOH**

*Specifications of sodium hydroxide (NaOH).*

function. Sodium silicate is a versatile, inorganic chemical manufactured by com-

**Constituents Percentage (%)** SiO2 66.87 Fe2O3 4.41 Al2O3 23.34 CaO 1.17 MgO 0.31

**Constituents Percentage (%)** SiO2 31.79 Fe2O3 0.49 Al2O3 17.07 CaO 38.78 MgO 6.23

This process gives a variety of products with unique chemistry that are used in many industrial chemistry that are used in many industrial and consumer applications.

Six different mix proportions shall be considered viz.; GB-1, GB-2, GB-3, GB-4,

GB-5 and GB-6. The slag sand shall be mixed with portions of IOT as a partial replacement with the following percentages; 20, 30 and 40% of the total dry mix. Fly ash (15%) and ground granulated blast furnace slag (15%), which are kept constant, all together contribute 30% of the total dry mix. The molarity of the sodium hydroxide solution adopted shall be 8 and 10 M. The alkaline solution shall contribute 10% of the total mix. The optimum moisture content adopted shall be 8%. The Na2SiO3 to NaOH ratio adopted shall be 2.5. Alkaline solution to binder

Potable water is used for the manufacturing of geopolymer bricks.

bining different ratios of sand and soda ash at high temperature.

M 40.0 g/mol Assay (NaOH) ≥97% Carbonate (Na2CO3) ≤2% Heavy metals (as Pb) ≤0.002%

**44**

*2.1.7 Water*

**2.2 Mix proportion**

*Mix proportions of geopolymer bricks.*

material ratio adopted shall be 0.35. (Please refer to **Table 8** for the mix proportion including the molarity).
