MIX DESIGN FOR INCORPORATING FINE AGGREGATE REPLACING MATERIALS: A REVIEW

Lalitha G, K.N. Vishwanath

Abstract: One of the main ingredients of concrete is fine aggregate. The natural sand which is now in scarcity is to be replaced by the alternative material. With that concern the crushed stone known as Robo sand has been used as an alternate material. The dust particles obtained from the quarry are fine grained below 4.75 mm IS sieve or mechanically crushed stone dust by grinding the un-sized and waste rock mass at stone quarry are now being used as an alternate fine aggregate in place of natural river sand. In the concrete mix design as per code, natural river sand is being blindly replaced by manufactured sand (Robo sand). The side effects of this unscientific replacement in designed mortar or concrete mix is being reflected in the form of spalling, micro structural cracks in the work completed. Hence it is essential to have a proper mix design procedure involving manufactured sand and such other Fine Aggregate Replacing Materials [FARM]. The project is an attempt to arrive at a feasible mix design procedure involving FARM in the mortar or concrete mix. On the lines of IS code trial mix designs are developed involving FARM. The casted and cured specimens by the prepared mix are put to mechanical test for determination of designed strength. The physical tests such as (SEM) Scanning Electronic Machine and X-Ray Powder Diffraction (XRD) are analysed for the formation of crystalline structures and the density of the structural element cast. Based on the mechanical and physical test results, a mix design and an empirical formula are arrived at. These formulas are validated through repeated tests.

Keywords: Robo Sand, Mix Design, FARM- Fine Aggregate Replacing Material, Empirical Formula, Validation

DOI: https://doi.org/10.15623/ijret.2017.0614007