**4. Alkaline activation of fly ash**

The further study about ashes found that they are having similar properties like cement and close brothers of cement (see **Figure 13***).* And many studies show that alkaline activation of ashes can make a stronger material to stabilize earth to build the road. By studying the same concept, this experimental programme came up with new experimental criteria to build noncement but fly ash-stabilized earth blocks. The experimental criteria are as follows.

#### **4.1. The experimental criteria to alkaline activate the fly ash**

The study shows that the concept of geopolymer can be applied to replace the cement in the mud concrete technology.

**Figure 13.** Comrades of cement.

The study shows the use of NaOH, and salt combination can activate the fly ash into the cementitious property. The process of geopolymerization is shown in **Figure 14**. Also known as polycondensation of alumina silicate bonds into jelly particle, they finally create the bond. This is not a novel concept; see Section "Introduction". However, this is the first time geopolymerization is an experiment with mud. The idea of stabilizing mud and developing mud-based mixture is to develop quick flow self-compacting mixture to alter a traditional compressed earth block technology. It was the mother research of this study which has found that utilizing mud can develop self-compacting mixture to alter compressed earth blocks [30].

The experimental programme started with a varying activator to identify the optimum alkaline solution to stable the mud concrete block as shown in **Table 7**. This is due to the different alumina silicate composition in the soil. However, after that, the salt content to dissolve the activator was identified. The results show that the optimum of 2% of the dry weight of the mixture can get the optimum strength for mud concrete block. And then, a profound mix was developed to test the required moisture content to make the mixture. For the mud concrete, the moisture ratio is critical to making a self-compacting mixture. The idea of self-compacting is to reduce the energy consumption of the mixture.

**Figure 14.** Experimenting with polymerizing mud concrete.

from many industrial by-products fly ash (FA), bottom ash and rice husk ash. These by-products

The further study about ashes found that they are having similar properties like cement and close brothers of cement (see **Figure 13***).* And many studies show that alkaline activation of ashes can make a stronger material to stabilize earth to build the road. By studying the same concept, this experimental programme came up with new experimental criteria to build non-

The study shows that the concept of geopolymer can be applied to replace the cement in the

cement but fly ash-stabilized earth blocks. The experimental criteria are as follows.

**4.1. The experimental criteria to alkaline activate the fly ash**

are usually disposed in landfills, which create serious environmental concerns.

**4. Alkaline activation of fly ash**

164 Cement Based Materials

mud concrete technology.

**Figure 13.** Comrades of cement.


**Table 7.** Experimental mix design for geopolymerizing fly ash-based mud mixture.

There are more than enough literature as well as the optimum mole content can be calculated. But since this is a practical product, it is better to establish the optimum caustic soda content to build mud concrete blocks out of fly ash and caustic soda [31–34]. The study shows that the required water mole content to produce the reaction is 20%. It is the required moisture content to produce the fly ash block. The moisture content is very important to develop the workability of the block mixture. The quick flow mixture shall help to improve the self-compacting capacity of the mixture. And the water in mud concrete block helps to improve the porosity and porosity helps to improve the thermal property of the block. The next step is the water content analysis, which was to find out the most suitable mix proportions to build fly ash-stabilized earth blocks. As per the results indicated in the previous experiment, the best compressive strength was shown when the moisture content was in between 15 and 20%. The

**Figure 15.** Optimizing NAOH.

results obtained are shown in **Figures 15**–**17**. After the confirmation of water content, the mix proportion was started varying the sand and gravel combinations as shown in **Figure 18**.

Alternative Stabilizer for Mud Concrete http://dx.doi.org/10.5772/intechopen.76065 167

The use of invented stabilizers was tested upon different soil combinations to see the strength development. And then, they were employed to build a walling sample width of 1 m and a height of 1 m. Out of the entire study, the most vulnerable and practical stabilizers were selected to develop this walling samples test. A 1-m wide 1-m tall building wall sample was made at the University premises to check the practicality of this new mix as shown in **Figure 19**. The practical use and mass scale production were studied in this process and found that natural rubber should be avoided as alternative stabilizers. Geopolymerization of waste ashes such as fly ash, bottom ash and especially the rice husk ash has the quality of replacing

**5. Application in construction**

**Figure 18.** Geopolymerized mud concrete block final results.

**Figure 17.** Optimizing moisture content.

the cement and build a novel walling material.

**Figure 16.** Optimizing NACL.

**Figure 17.** Optimizing moisture content.

There are more than enough literature as well as the optimum mole content can be calculated. But since this is a practical product, it is better to establish the optimum caustic soda content to build mud concrete blocks out of fly ash and caustic soda [31–34]. The study shows that the required water mole content to produce the reaction is 20%. It is the required moisture content to produce the fly ash block. The moisture content is very important to develop the workability of the block mixture. The quick flow mixture shall help to improve the self-compacting capacity of the mixture. And the water in mud concrete block helps to improve the porosity and porosity helps to improve the thermal property of the block. The next step is the water content analysis, which was to find out the most suitable mix proportions to build fly ash-stabilized earth blocks. As per the results indicated in the previous experiment, the best compressive strength was shown when the moisture content was in between 15 and 20%. The

**Figure 15.** Optimizing NAOH.

166 Cement Based Materials

**Figure 16.** Optimizing NACL.

**Figure 18.** Geopolymerized mud concrete block final results.

results obtained are shown in **Figures 15**–**17**. After the confirmation of water content, the mix proportion was started varying the sand and gravel combinations as shown in **Figure 18**.

#### **5. Application in construction**

The use of invented stabilizers was tested upon different soil combinations to see the strength development. And then, they were employed to build a walling sample width of 1 m and a height of 1 m. Out of the entire study, the most vulnerable and practical stabilizers were selected to develop this walling samples test. A 1-m wide 1-m tall building wall sample was made at the University premises to check the practicality of this new mix as shown in **Figure 19**. The practical use and mass scale production were studied in this process and found that natural rubber should be avoided as alternative stabilizers. Geopolymerization of waste ashes such as fly ash, bottom ash and especially the rice husk ash has the quality of replacing the cement and build a novel walling material.

achieved the required strength but there were many practical issues when it comes to the physical use of rubber-stabilized earth blocks. Then, a study was done with a series of natural polymers taken from other plants such as pines, chews, and so on. The results are good enough but practically cannot be applied in the real world where the mass produc-

Alternative Stabilizer for Mud Concrete http://dx.doi.org/10.5772/intechopen.76065 169

Then, the study was focused to utilize industrial waste into cementitious materials for mud concrete block. Fly ash, bottom ash and rice husk ash were subjected to this study and found astonishing results. The initial results with a raw form of waste were failure and they did not produce the required strength. And then, the developed mixture with alkaline solution creates much better strength with mud concrete block. After finalizing the mix and all, a sample wall area of 1 m × 1 m was built to check the practical application of this block to produce affordable walling. And it was noticed that highly alkaline solutions make the mixture somewhat difficult. The expanded study was conducted to rank the alternative stabilizers discovered in this study. The developed stabilizer was ranked according to their workability availability and the initial cost. And then, the extensive study was conducted with life cycle cost and carbon footprint analysis to understand the long-term use and the environmental

This material is based on the work supported by the NSF (National Science Foundation of Sri Lanka) grant number under RG/2017/EA & ICT /02. Any options, findings and conclusions or

[1] Udawattha C, Halwatura R. Thermal performance and structural cooling analysis of br-ick, cement block, and mud concrete block. Advances in Building Energy Research.

[2] Udawattha C, Halwatura R. Embodied energy of mud concrete block (MCB) versus

brick and cement blocks. Energy and Buildings. 2016 Aug;**126**(0):28-35

recommendation expressed in this material are those of the authors.

Chameera Udawattha\* and Rangika Halwatura

University of Moratuwa, Sri Lanka

\*Address all correspondence to: udawatthe@gmail.com

tion of earth blocks is required.

impact of those stabilizers.

**Acknowledgements**

**Author details**

**References**

2016:1-14

**Figure 19.** Fly ash geopolymerized mud concrete masonry unit wall.
