**4.1 Compressive strength and thermal conductivity test results**

As described in previous chapter, i.e. Chapter 3, all the design and nominal mix samples in respect of Concrete of various grades starting from M-15 to M-25 were put to test to determine various physical and thermal parameters. Similarly, Mortar mix samples of various proportions with respect to two most used grades MM3 and MM5 were put to tests. The tests performed on those samples were of destructive and nondestructive in nature. The tests are essential for durability and application worthiness of such concrete and mortar mixes (**Figures 8**–**15**).

**Figure 8.** *Compressive strength of concrete mix (refer Table 2 for mix proportion).*

**Figure 9.**

*Thermal conductivity test results of concrete mix (refer Table 2 for mix proportion).*

#### **Figure 10.**

*Compressive strength test of concrete mix (refer Table 3 for mix proportion).*

It may be seen from the above plotted results, bottomash blended concrete offers M-25 grade strength up to 40% replacement and M-20 grade strength up to 80% replacement of sand. Fly ash blended concrete gives marginally lower results.

It may be seen from the above plotted thermal conductivity test results, both fly ash and bottom ash blended concrete offer reduced thermal conductivity than conventional concrete mix.

From the above plotted result, it may be observed that flyash-lime dust (38) and bottomash-limedust (41) blended mix in the ratio of 67:33 offer M-20 grade strength and same combination with 75:25 ratio offer close to M-20 grade strength.

*Coalash as Sustainable Material for Low Energy Building DOI: http://dx.doi.org/10.5772/intechopen.101858*

**Figure 11.** *Thermal conductivity test of concrete mix (refer Table 3 for mix proportion).*

#### **Figure 12.**

*Compressive strength test of mortar mix (MM3) (refer Table 4 for mix proportion).*

Mixes 38 (flyash:limedust::67:33) and 41 (bottomash:limedust::67:33) offer lower thermal conductivity value.

From the above plotted result, it may be observed that up to 60% replacement of sand by flyash, strength remains within MM-3 grade required criteria.

Reduction in thermal conductivity value follows same trend by fly ash and bottom ash blended mortar mixes respectively.

Flyash-limedust (2) and bottomash-limedust combination offer MM-3 grade strength compatibility.

Considerable reduction in thermal conductivity values observed in both flyash (2, 3, 4) and bottomash (5, 6, 7) blended mixes with respect to the conventional mix (1).

#### **Figure 13.**

*Thermal conductivity test results of mortar mix (refer Table 4 for mix proportion).*

#### **Figure 14.**

*Compressive strength test values of MM3 grade mortar (total replacement of sand by flyash, lime dust, marble dust, bottomash) (refer Table 5).*

#### **4.2 Test result for overall heat transfer co-efficient (U-value)**

The hot side temperature of 40°C, and cold side temperature of 25°C were maintained for 3 consecutive days. Both the brick wall panels with conventional mortar and plaster combination and fly ash-lime dust combination were tested under identical test parameters. In steady state condition, average standard deviation in brick surface temperature of both days of testing was 0.056°C on both the hot and cold side. The experimentally obtained U-values for both the cases and final difference thereof is shown in **Table 6**.

*Coalash as Sustainable Material for Low Energy Building DOI: http://dx.doi.org/10.5772/intechopen.101858*

#### **Figure 15.**

*Thermal conductivity test results of mortar mix (refer Table 5).*


#### **Table 6.**

*Final result of wall panel U-value.*

## **5. Economical and environmental benefits**

A square shaped room of size 10 m2 plan area and four wall size each of 10 m<sup>2</sup> is considered for such energy and economic analysis at Kolkata, India location.

#### **5.1 Assumptions**



#### **Table 7.**

*Economic and environmental analysis.*

