Design a concrete mix for reinforced concrete beams of astructure. The structure is located in a locality wherein water hasexcess of chlorides in it. Required average compressive strength ofconcrete has been determined to be 4700 psi. Beams havecross-section of 9 in. x 21 in. reinforced with 4 # 6 bars.Reinforcement has a concrete cover of 1.25 in. and there is a clearspace of 1.0 in. between form surface and steel bars. Fineaggregate has bulk specific gravity (SSD) of 2.63; absorptioncapacity of 1.25%; surface moisture of 3.0% and a fineness modulusof 2.75. Coarse aggregate has bulk specific gravity (SSD) of 2.70;absorption capacity of 2.50 %; surface moisture of 1.75% based onSSD state and dry-rodded unit weight of 110 lb/ft3. Design concretemix following the step-by-step method of ACI 211.1-91 for thesubject beams and tabulate the quantities of ingredient materialsin lb/yd3, lb/ft3 and 1.5 lb/ft3. Provide reference of relevant ACITables in each step.
