asonry is constructed with bricks and mortar. Masonry walls are cheap, and have good sound and insulation properties. The surface characteristics of the brick may not influence the bond between the bricks. Venumadhava Rao et al. 1995 made a preliminary study on the influence of bond strength on the compressive strength of masonry. Goodwin and West (1992) McGinley (1990) suggested that both the mortar quality and the surface absorption criteria of the masonry unit are the most significant parameters in developing good bond strength.
This experimental study has aimed at following objectives ? To produce Geopolymer bricks with partial replacement of Fly ash by GGBS (50:50) ? To determine the percentage of water absorption and compressive strength of Geopolymer bricks (Fly ash to GGBS, 50:50) and compared with the locally available burnt clay bricks.
? To determine Triplet shear and shear bond strength of Geopolymer bricks (Fly ash to GGBS, 50:50) and compared with the locally available burnt clay bricks.
III.
? Geopolymer bricks were prepared with partial replacement of Fly ash by GGBS varying from 0 to 100%. IV.
Clay bricks and a Geopolymer fly ash brick partially replaced by GGBS was used to study the strength properties of the masonry unit. The compressive strength of burnt clay brick and Geopolymer bricks ( varying percentage of GGBS replaced to fly ash), are being presented in Table 1 & 2, The water absorption of burnt clay brick and Geopolymer bricks (Fly ash: GGBS, 50:50) are shown in Table 3 & 4
? It was observed that the compressive strength of Geopolymer bricks with partial replacement of Fly ash with GGBS increases up to 100%. The compressive strength of burnt clay brick is 3.5 N/ mm 2 ; the substitute of fly ash to GGBS is (50:50). ? It was observed that the percentage of water absorption of Geopolymer bricks is 5.90% less than the ordinary burnt clay bricks. ? It was observed that the triplet shear bond strength, with 1:6 cement mortar, strength of Geopolymer bricks was 62% greater than ordinary burnt clay bricks. ? It was observed that the shear bond strength with 1:6 cement mortar, Geopolymer bricks are 48% greater than ordinary burnt clay bricks. ? Incorporation of GGBS as partial replacement to Fly ash in the preparation of Geopolymer bricks resulted in the reaction of pozzolana with calcium hydrate which produced calcium silicate hydrate, thus enhancing the compressive strength and shear bond strength of the brick masonry with the modification of the microstructure of the mortarbrick unit interface.
| Sl. No. | Size of burnt clay bricks (mm) | Area (mm 2 ) | Load (KN) | Compressive strength (N / mm 2 ) | Average compressive Strength (N/mm 2 ) |
| 1 | 112 | 5.09 | |||
| 2 | 126 | 5.72 | |||
| 3 | 098 | 4.45 | |||
| 4 | (220 x 100 x 75) | 22000 | 126 | 5.73 | 5.25 |
| 5 | 116 | 5.27 |
| Sl. No. | Fly ash: GGBS | Average compressive strength (N / mm 2 ) |
| 1 | 100 : 00 | 00.87 |
| 2 | 90 : 10 | 01.35 |
| 3 | 80 : 20 | 02.04 |
| 4 | 70 : 30 | 02.45 |
| 5 | 60 : 40 | 03.50 |
| 6 | 50 : 50 | 03.97 |
| 7 | 40 : 60 | 04.50 |
| 8 | 30 : 70 | 04.93 |
| 9 | 20 : 80 | 06.04 |
| 10 | 10 : 90 | 06.60 |
| 11 | 0 : 100 | 07.45 |
| Sl. No. | Dry weight (Kg) | Wet weight (Kg) | Water absorption (%) | Avg. water absorption (%) |
| 1 | 3.48 | 3.15 | 10.47 | |
| 2 | 3.43 | 3.11 | 10.28 | |
| 3 | 3.40 | 3.12 | 08.97 | 9.69 |
| 4 | 3.45 | 3.15 | 09.52 | |
| 5 | 3.41 | 3.12 | 09.23 |
| Sl. No. | Dry weight (Kg) Wet weight (Kg) | Water absorption (%) | Avg. water absorption (%) | |
| 1 | 3.01 | 3.28 | 8.97 | |
| 2 | 3.00 | 3.24 | 9.66 | |
| 3 | 2.96 | 3.24 | 9.66 | 9.11 |
| 4 | 3.02 | 3.32 | 9.93 | |
| 5 | 2.97 | 3.26 | 8.89 | |
| Sl. | Load | Size of brick | Area of brick | Shear bond | Avg. shear bond |
| No. | (KN) | (mm) | (mm 2 ) | strength | strength (N/mm 2 ) |
| 1 | 2.80 | 0.063 | |||
| 2 | 3.00 | 0.068 | |||
| 3 | 2.90 | (220 x 100 x 75) | 22000 | 0.065 | 0.064 |
| 4 | 2.80 | 0.063 | |||
| 5 | 2.79 | 0.063 |
| Sl. No. | Load (KN) | Size of brick (mm) | Area of brick (mm 2 ) | Shear bond strength | Avg. shear bond strength (N/mm 2 ) |
| 1 | 3.8 | 0.172 | |||
| 2 | 3.7 | 0.168 | |||
| 3 | 3.6 | (220 x 100 x 75) | 22000 | 0.163 | 0.168 |
| 4 | 3.7 | 0.168 | |||
| 5 | 3.8 | 0.172 |
| Sl. No. | Load (KN) | Size of brick (mm) | Area of brick (mm 2 ) | Shear bond strength | Avg. shear bond strength (N/mm 2 ) |
| 1 | 0.8 | 0.106 | |||
| 2 | 0.8 | 0.106 | |||
| 3 | 0.9 | (220 x 100 x 75) | 22000 | 0.120 | 0.114 |
| 4 | 0.9 | 0.120 | |||
| 5 | 0.9 | 0.120 |
| Sl. No. | Load (KN) | Size of brick (mm) | Area of brick (mm 2 ) | Shear bond strength | Avg. shear bond strength (N/mm 2 ) |
| 1 | 3.8 | 0.222 | |||
| 2 | 3.7 | 0.216 | |||
| 3 | 3.6 | (220 x 100 x 75) | 22000 | 0.210 | 0.217 |
| 4 | 3.7 | 0.216 | |||
| 5 | 3.8 | 0.222 |
The author would like to thank Dr. D S Suresh, Director, and Principal, C I T. Gubbi, for the encouragement throughout the work. The author is also indebted to management authorities for their wholehearted support. The author is also grateful to all the teaching & nonteaching faculties for their encouragement.