Replacement of Fine Aggregate with Pond Ash in Concrete

Abstract

The increase in demand for concrete and its constituents has resulted in the scarcity of natural resources, which has encouraged for interest in the research to look for alternative materials which could satisfy both the strength and performance criteria of concrete constructions. Pond ash, a waste product of Thermal Power Plants is one such material, that can be adopted as a suitable material as Fine aggregate in concrete , replacing Natural Sand partially or fully. Encouraging the usage of such a waste material as constituent in concrete so as to address the issues related to its disposal, en- vironmental and ecological problems, is a social responsibility of researchers, thus contributing to 3Rs - Reduce Reuse and Recycle, there by promoting sustainable construction. Experimental study is conducted to explore the feasibility of using pond ash in concrete as replacement of fine aggregate with varying percentages such as 20%, 40%, 50%, 60%, 80% and 100%. M-25 and M40 grades of concrete are produced, tested and compared in terms of the mechanical properties such as compressive strength, split tensile strength and exure strength with control concrete. The re- sults of mechanical properties suggested that PA00 mix performed better than all the pond ash concrete mixes. The M25 and M40 grade concrete incorporating pond ash as fine aggregate replacement up to 40% showed significant improvement of 8% in compressive strength for M25 grade of concrete and 13.8& improvement for M40 grade of concrete at the age of 90 days. Reduction of 4% and 10.7% in exure strength was observed for PA40 concrete mix as compared to that of PA00 mix for M25 and M40, respectively at the age of 90 days. The concrete with pond ash as 40% replacement of fine aggregate showed improvement of 9.9% and 2.6% in split tensile strength as compared to that of control concrete for M25 and M40, respec- tively at the age of 90 days. Durability properties such as sulphate resistance and chloride resistance for M25 and M40 grade control concrete and concrete incorporating pond ash as 40% re- placement of fine aggregate is evaluated. The compressive strength of M25 grade concrete mix incorporating pond ash as 40% fine aggregate replacement increased 32.35% as compared to 12.93% of control concrete mix after 90 days of sulphate exposure, respectively with respect to that of the initial compressive strength before exposure. The compressive strength of M40 grade concrete mix incorporating pond ash as 40% fine aggregate replacement increased 41.20% as compared to 15.43% of control concrete mix after 60 days of sulphate exposure, respectively with respect to that of the initial compressive strength before exposure. The compressive strength of M25 grade concrete mix incorporating pond ash as 40% fine aggregate replacement increased 20.42% as compared to 5.62% of con- trol concrete mix after 90 days of chloride exposure, respectively with respect to that of the initial compressive strength before exposure. The compressive strength of M40 grade concrete mix incorporating pond ash as 40% fine aggregate replace- ment increased 41.87% as compared to 15.43% of control concrete mix after 60 days of chloride exposure, respectively with respect to that of the initial compressive strength before exposure. Results of mechanical properites and durability properties of concrete mix in- corporating pond ash as 40% fine aggregate are either at par or better then control concrete. Thus suggesting that fine aggregate can succefuully be replaced up to the extent of 40% by pond ash in concrete.