Utilization of riverbed silt and subsoil of Gopalganj for masonry bricks incorporating internal fuel and comparison of their construction properties with commercial bricks

Abstract

Agricultural topsoil is the most common raw material for making clay bricks in Bangladesh because of its abundance and prehistoric tradition. This practice of the bygone age is steadily pushing the environment toward the risk of fertile soil depletion. At the same time, the largest delta of this world gathers tons of sediment during the monsoon while bearing the havocs of floods due to the loss of navigability of the rivers. It propels the government to expend more on dredging. According to soil science, particle size is the only difference between clay and silt. Thus, bricks can be thought to be made from the Himalayan silt along with agricultural subsoil. However, this replacement will bring some adverse effects on the construction properties which need to be assessed. Along with the depletion of fertile topsoil, the brick sector exaggerates the environment by emitting fine particles from coal-burning during vitrification. This hazard can be lessened by incorporating internal fuel. In this work, we represent a method to produce masonry bricks by substituting the topsoil completely with riverbed silt and subsoil. The novel feature is a comparison of those silty bricks with commercial bricks available in the market to perceive the real difference in construction properties. Principally, the study presents a realistic evaluation of silt-made bricks as a building material insinuating the potential of a sustainable source of raw material for masonry bricks.

Appendices

Appendix A: Detail calculation for the test specimens

See Tables

Table 3 Dimension of kiln-fired clay–silt bricks (Type-1) after firing

3,

Table 4 Water absorption and strength test of kiln-fired clay–silt bricks (Type-1)

4,

Table 5 Compressive strength test of kiln-fired clay–silt bricks (Type-2)

5,

Table 6 Compressive strength test commercially produced bricks in different brick kilns

6,

Table 7 Dimension of kiln-fired clay–silt–ground sand bricks (Type-3) after firing

7,

Table 8 Water absorption and strength test of kiln-fired clay–silt–ground sand bricks (Type-3)

8,

Table 9 Water absorption and strength test of furnace-fired clay–silt bricks (Type-A)

9.

Appendix B: Physical appearance of the bricks

See Table 10, 11.

Table 10 Physical appearance of kiln-fired clay–silt bricks

Table 11 Physical appearance of kiln-fired clay–silt–ground sand bricks

Appendix C

Sample calculation

Sample calculation for a Type-1 clay–silt brick containing 30% silt is presented below.

Calculation for amount of raw material in brick soil mixture

Total clay mixture for green brick = 1800 gm.

Percentage of silt in clay mixture = 30 wt%

Therefore, Amount of silt in clay mixture = 1800 × 0.30 = 540 gm.

Amount of agricultural soil in clay mixture = 1800 − 540 = 1260 gm.

Amount of coal particle as internal fuel = 50 gm.

Calculation for water absorption test (wet basis)

Weight of saturated surface-dried brick, SSD = 1493 gm.

Weight of oven-dried brick, OD = 1240 gm.

Therefore, water absorption = $\frac{SSD-OD}{SSD}\times 100= \frac{1493-1240}{1493}\times 100=16.95 wt\%$

Calculation for compressive strength test

Length of fired brick after oven-dry = 113.35 mm.

Width of fired brick after oven-dry = 107.47 mm.

Load = 115 kN.

Therefore, Area of fired brick after oven-dry = 113.35 × 107.47 = 12,181.72 mm².

Actual load = 1.026 × load − 11.59.

 = 1.026 × 115 − 11.59.

 = 106.40 kN.

 = 106,400 N.

Now, Compressive strength, CS = $\frac{\mathrm{Actual load}}{\mathrm{Area}}$

$$= \frac{106400 N}{12181.72 {\mathrm{mm}}^{2}}$$

$=8.7 \frac{N}{{\mathrm{mm}}^{2}}$ or MPa.

For Type-3 bricks, 5% of the clay mixture, i.e., 90 g cement and ground sand has been used, respectively.