2.1.2. Preparation of samples

Two grades of masonry mortar MM3 and MM5 (corresponding 28 days compressive strength values should be no less than 3 N/mm² and 5 N/mm²) as per IS 2250 (1981, Reaffirmed 2000) were selected for evaluation. These two grades are conventionally used throughout the country, with Cement-sand ratios of 1:6 and 1:4 respectively. In the experimental work, sand was gradually replaced by fly ash in one series of mix (A-Series, A,A-1,A-2,…..A-10), and by bottom ash in another (B-Series, B,B-1,B-2,….B-10), within the same grade of mortar MM3 (Table 4). Similarly for another grade MM5, such combinations were followed (Table 5). Sand less mortars with fly ash, bottom ash and marble dust combinations under MM3 and MM5 Grade are shown against Tables ​Tables66 and ​and77 respectively. There were fifty different combinations of mortar mixes, among which two were control mix, wherein sand was used as fine aggregate conventionally. For each combination of mix, three nos. 50 mm* 50 mm*50 mm mortar cube moulds, and pairs of 50 mm*50 mm *12 mm mortar square moulds were prepared. The samples were de-moulded after 24 hours of casting and kept immersed in potable water till 28 days at room temperature. After 28 days of water curing, samples were taken out of water, wiped clean and kept at room temperature before performing subsequent tests. Three cubes were tested to determine compressive strength of each sample, and pairs of sample of 12 mm thickness were tested for thermal conductivity parameter respectively. After compiling all the test results, the C-5 mix was identified under MM5 mortar grade category, being the lowest complied mix with 50% substitution of sand by flyash with thermal conductivity value reduction to the tune of 49.31%, in comparison with control mix with 100% sand for evaluating the overall heat transfer co-efficient (U-value) of masonry wall panel. The conventional burnt clay bricks were collected from the local market, and the brick wall panel of 125 mm thickness and of size 480 mm*480 mm was constructed with masonry mortar within wooden frame size of 500 mm*500 mm. Two sets of such panels with identical bricks, Portland pozzolana cement (PPC), sand, flyash etc. were constructed named as Set-1 and Set-2. In Set-1, mortar mix composition was PPC + 50% Sand and 50% Flyash combination mortar in 1:4 proportion (C-5 mix under Table 5 of MM5 Grade). The same mix was adopted for 12 mm thick plastering on both sides of wall panel, and after subsequent curing, 2 mm (approx.) white putty for evenness of the surface and two coats of acrylic paints were applied. Same steps were followed for construction of Set-2 panel with 100% sand combination (Control mix under Table 5 of MM5 Grade). The putty and two coats of acrylic paints had been applied to create an identical actual scenario of building wall surface, wherein the putty and paints both form some impervious blanket against moisture penetration by sealing the surface pores up to certain extent.

Gradual replacement proportion of Sand by Fly ash and Bottom ash (separately) for MM3 Grade Mortar mix.

Gradual replacement proportion of Sand by Fly ash and Bottom ash (separately) for MM5 Grade Mortar mix.

Total replacement proportions of Sand by Fly ash and Bottom ash (separately) in association with natural mineral (lime dust) and another industrial residue (marble dust) combination mix for MM3 Grade Mortar.

Total replacement proportions of Sand by Fly ash and Bottom ash (separately) in association with natural mineral (lime dust) and another industrial residue (marble dust) combination mix for MM5 Grade Mortar.