Explain the steps involved in concrete mix design using IS method.

IS mix design procedure involves: (1) Determine target mean strength = fck + 1.65*s (s = standard deviation), (2) Select water-cement ratio based on exposure condition and strength requirement, (3) Select water content based on aggregate size and workability, (4) Calculate cement content from w/c ratio and water content, (5) Estimate aggregate proportions based on maximum aggregate size, grading zone, and required workability, (6) Conduct trial mixes and adjust for actual aggregate properties. Final mix is selected after testing meets strength and workability requirements.