Question

While designing reservoirs, indirect tensile strength of the concrete mix is particular to be less than a specific value such as 2.8N/mm2 for potable water. Why ought to engineers put an upper bound of indirect tensile strength?

Answer

Crack width formation is dependent on early tensile power of concrete. Principle of critical steel ratio too applies in the situation. Amount of reinforcement necessary to control early thermal and reduction movement is determined by capability of reinforcement to induce cracks on concrete structures. If a higher limit is set on the early tensile force of undeveloped concrete, then a choice of tiny cracks will be formed by failing in concrete tension. But, if strength of reinforcement is lower than undeveloped concrete, then subsequent yielding of reinforcement will create isolated and wide cracks that are undesirable for water-retaining structures. So, in order to control formation of such broad crack widths, concrete mix is specified to have a not direct tensile power at seven days not exceeding a sure value