Advanced Materials — Worked Examples

An SCC trial has a large, stable slump-flow spread but visibly blocks when passing through the reinforcement-simulating bars of the specified passing-ability test. Interpret the result.

A UHPC trial reaches the target compressive strength, but cut surfaces reveal severe steel-fiber clustering and regions with very few fibers. Determine the quality response.

An existing concrete beam is proposed for externally bonded CFRP strengthening, but the soffit contains laitance, patches, and localized delamination. Determine the materials-QA sequence before capacity calculations rely on the FRP system.

A weak saturated subgrade needs separation from crushed aggregate and also needs improved aggregate confinement. A contractor proposes using either a geotextile or a geogrid, whichever is cheaper. Determine the functional selection logic.

A trial mixture requires $900\text{ kg/m}^3$ RCA coarse aggregate at SSD. Absorption is 5.0% and total moisture is 7.0%, both on an OD basis. Determine wet batch mass and free water above SSD.

A repair mortar develops very high compressive strength, but pull-off testing shows repeated failure at the repair-to-concrete interface. Determine which property governs the repair decision.

Two systems repair the same $100\text{ m}^2$ bridge-deck area for a 40-year study period. System A has an initial impact index of 100 but is expected to be replaced at years 10, 20, and 30. System B has an initial index of 150 and one maintenance intervention with impact index 25 at year 20. Ignoring discounting and other life-cycle stages for this screening example, compare the stated impact totals.

Conductive-additive concrete coupons show repeatable electrical-resistance change under cyclic compression. A project team proposes replacing conventional bridge inspection with this sensing response. Determine whether the evidence is sufficient.