Practical ultra-high-strength concrete for precast concrete applications

[摘要] Ultra-high-performance concrete (UHPC) has beensuccessfully used in many highway bridges in theUnited States. However, the use of UHPC in theconstruction of prestressed concrete bridge girders is stilllimited, even though research has demonstrated UHPC’s excellent strength and durability characteristics compared withthose of conventional concrete or high-strength concrete(HSC).1 The reasons for the limited use of UHPC are mainlythe production and material costs, the need for specialequipment (such as a large, high-shear-capacity mixer),and insufficient production experience with the material.2Because UHPC requires high proportions of silica fume,silica powder, and steel fiber, and a high dosage of water-reducing admixtures, UHPC mixtures cost several times morethan conventional mixtures. Production costs are higher forUHPC because it requires longer mixing and curing operations. This paper focuses on developing economical ultrahigh-strength concrete (UHSC) that can be mixed, placed,and cured with the same equipment used for conventionalconcrete at a precast concrete facility. This study presentsa modified cross section and a flexural design for a 300 ft(91.4 m) long bridge girder using the proposed UHSC and0.7 in. (18 mm) diameter prestressing strands.

[学科分类] 建筑学