Question
Would a concrete structure be entirely free of expansion joints and contraction?
Answer
Consider that concrete structure is not subject to problem of disparity settlement. For contraction joints, it might be possible designing a concrete structure without contraction joints. Using sufficient steel reinforcement to spread equally crack width over span length of structure, it might achieve requirement of minimum crack width and cause no undesirable impact to aesthetics of structure. Though, it follows that amount of reinforcement required is higher than that with sufficient contraction joints.
For expansion joints, consequence of not providing such joints could be complex to cater for. As in, a concrete structure has coefficient of thermal extension of 9x10-6 /C and a Young's modulus of 34.5kN/mm2. With incensement of temperature of 20oC and it is confidential to free expansion, then structure is subject to axial pressure of 6.21MPa. If structure is especially slender as in concrete carriageway, buckling could occur. As a result, structure has to be designed to get up these thermal stresses if development joints are not offered. Still, for water retaining structures, mainly of them are not affected by weather conditions as they are insulated from water they have internally and soil backfill that surround them. So, it is expected that smaller quantity of thermal movement will happen when compared with regular exposed concrete structure. Therefore, development joints could be lost in this case with view that compressive stress induced by thermal expansion toughens structure to limit increase of tensile stress.