Effect of Partial Replacement of Cement in Self-Compacting Concrete by Fly Ash and Metakaolin

Abstract

Self-compacting concrete (SCC) generally requires cement and chemical admixtures of high material cost. The use of mineral admixtures (such as fly ash, metakaolin etc.) as partial replacement of cement in SCC can bring down the cost. The use of industrial wastes such as fly ash, metakaolin etc in the binder of concrete reduces the storage, disposal and environmental problems. In the present study, the effects of partially replacing cement of self-compacting concrete by mineral admixtures (fly-ash and metakaolin) on (i) fresh state flow properties, (ii) 28 days compressive, splitting tensile and flexural strengths at room/standard temperature and (iii) 28 days compressive strengths at elevated temperatures. In the present study the mix design for M40 grade SCC was first carried out in accordance with EFNARC guidelines. The cement in SCC was partially replaced with (a) 5 % of flyash and 3% of metakaolin, (b) 5 % of flyash and 6% of metakaolin, (c) 5 % of flyash and 9% of metakaolin, (d) 15 % of flyash and 3% of metakaolin, (e) 15 % of flyash and 6% of metakaolin, (f) 15 % of flyash and 9% of metakaolin, (g) 25 % of flyash and 3% of metakaolin, (h) 25 % of flyash and 6% of metakaolin and (i) (a) 25 % of flyash and 9% of metakaolin. Tests such as slump flow, V-funnel, L-box, U-box, J-ring were carried out on fresh concrete. Conventional compressive strength test was carried out on hardened self-compacting concrete (SCC). The initial tangent modulus of SCC was also determined during the test. Compressive strength was also determined at 28 days after heating the specimens to 100 o C, 200 o C and 300 o C in a furnace for 6 hours. The splitting tensile test was conducted on SCC cylinders at 28 days at standard temperature to determine the splitting tensile strength. The flexural test was conducted on beam specimens at standard temperature in universal testing machine to determine the flexural strength as well as the loaddeflection characteristics. It is observed that the replacement of cement by a combination of fly ash and metakolin in the range of 8 to 34 percent has no adverse effect on the workability properties of SCC. As the percentage of cement replacement increases, the 7 days and 28 days compressive strength, flexural strength, initial tangent modulus of SCC cubes increase up to 24 % and later decrease. The maximum splitting tensile strength of SCC cylinders at 28 days occurs for a percentage of cement replacement = 14 in the considered range. The minimum splitting tensile strength at 28 days occurs for a percentage of cement replacement = 28 in the considered range. The loss in compressive strength of SCC at elevated temperature is taken as a measure of durability against elevated temperature and it increases as the elevated temperature increases. The maximum loss of compressive strength at elevated temperature occurs at percentage of cement replacement = 8 in the considered range.

Analysis of Mechanical Properties of Self Compacted Concrete by Partial Replacement of Cement with Industrial Wastes under Elevated Temperature

“…. Comparative compressive strength trend with respect to cement replacement of previous studies (Gesoglu [7], Sadek [9], Heba [8], Sakthi [42] and Bharath [5]). Figure 3.…”

“…A few scientists have recently proposed another technique of blend plan and forecast of solid quality utilizing neural organize. Additionally, a few works were accounted for on the utilization of neural organize based demonstrating approach in anticipating the solid quality [5][6][7][8][9][10][11][12][13][14]. A few endeavors have been made to portray the compressive quality properties utilizing conventional relapse investigation apparatuses and factual models [15][16][17].…”

“…Therefore, this research has contributed the comparison of Fly Ash and Marble powder with GGBFS not only at room temperature but also at elevated temperature. Furthermore, most previous studies only major focused on compressive strength [4][5][6]8,[10][11][12][13]. However, in this research tensile and flexural strength has also been studied.…”