International Concrete Abstracts Portal

To solve the durability problem of expansion joints and bearings, integral abutment bridges (IABs) have become increasingly popular. Soil Structure Interaction (SSI) is a fundamental aspect for reaching a thorough understanding of this type of structure not only for newly built bridges but also in the retrofitting of existing ones. Under imposed actions, e.g., horizontal expansion and contraction induced by thermal variation and time-dependent effects (creep and shrinkage), the connection between a super- and substructure responding as a frame structure makes IABs different from other conventional bridges that introduce forces due to SSI. Therefore, the overall horizontal stiffness is mainly due to i) the piles’ stiffness, which is usually flexible enough to allow for the deformation of the superstructure and strong enough to carry out the vertical loads, and ii) the type of soil behind the bridge abutment, which has a different stiffness depending on its compaction and composition. Several approaches have been proposed in the literature to consider these types of interaction. In this paper, the accuracy of different formulations commonly used in IABs’ design and based on p-y curves was evaluated. Formulations for piles and abutments were first introduced. Then, a fully integral abutment bridge built in China was considered as a case study. A finite element model of the bridge using SAP2000 software was implemented, and the influence of different methods and formulations was investigated. Finally, the obtained results for different types of soil and approaches were compared and discussed.

Type K Shrinkage Compensating Concrete (SCC) concrete is uniquely suited for use in slabs and walls because it typically requires fewer expansion joints than a convention portland cement (PC) concrete. This allows for continuous placement of much larger slabs and walls and facilitates the construction of high performance smooth slabs with few interruptions. Typically shrinkage-compensating concrete construction practice is to pour adjoining wall sections a minimum of five days apart in order to allow for the initial expansion of the material. The need for unrestrained expansion is implied in the ACI 223R-10 Design Guide in Chapter 5 in a discussion on sequencing the placement of wall segments. This paper discusses testing that was performed at two different locations, spanning both two different times of year and two unique climates. The tests used vibrating wire strain gages (VWSG) to investigate the restrained behavior of a wall segment in a six million gallon clear well tank in Springfield, IL, as well as the unrestrained behavior of two slabs-on-grade in Los Angeles, CA. Measurements were taken for a minimum of 30 days and a maximum of 170 days. Testing results are then compared to similar scenarios using ordinary PC concrete.

Concrete floor on ground represents an important application for concrete use in Italy. Despite their widespread use, a large percentage of concrete floors does not meet the performance requirements in terms of functionality and durability for various reasons; among them, restrained shrinkage cracking and curling represent one of the most important causes of defects. Cracking is mainly due to the drying shrinkage in presence of internal and external restraints, while curling is due to the shrinkage gradient due to the floor thickness. An analytical approach to shrinkage cracking and curling is often overlooked by designers in lieu of the design of contraction joints that allow the cracking of concrete under controlled conditions. Nowadays, the growing needs of concrete floors purchasers in terms of durability and functionality suggests the use of special concretes for flooring. For instance, the use of shrinkage-compensating concretes reduces the number of contraction joints and enhances the concrete slab performances. This study presents the non-linear finite element analysis of a jointless floor made with a shrinkage-compensating concrete obtained with the use of a blend of calcium sulpho-aluminate cement and ordinary Portland cement.

The undulating walls at the entry hall of the Museum of History of Polish Jews in Warsaw, Poland, were constructed using a stay-in-place form and the dry-mix shotcrete process. To avoid cracking of the walls, a support system was designed to distribute and disperse stresses from the anchorage points into the wall sections. To maintain a uniform thickness of shotcrete and delineate the outer surface, specially designed polymers strips were embedded in expansion and control joints. The strips also enabled installation of plastic sheets to prevent moisture loss and provided protection against shotcrete overspray during construction of adjacent elements.

A major limitation of the durability of bridge decks is the area around an expansion joint which allows drainage of de-icing salts to the underlying substructure. Fiber-reinforced concrete link slabs are proposed as a more durable alternative to traditional expansion joints. This study was developed to evaluate the possibility of using more common fiber-reinforced concrete (FRC) mixtures rather than the highly designed ultra-high performance fiber-reinforced concrete (HPFRC) with fibers that has often been recommended for link slabs. In this study, the matrix proportioning and the type and volume of polymeric and steel fibers have been investigated to determine their effects on compressive, tensile and flexural strength, fracture behavior and residual strength. A standard mixture design was first optimized for workability with one steel fiber type and one polymeric fiber type. With the optimal mixture design, a selection of six fiber types were then tested for the selected mechanical properties. Although the FRCs tested did not reach the performance of the HPFRC, significant increases in performance were observed with the common fibers that could be useful in the design of a FRC link slab with the most promising results obtained with hooked-end steel macro-fibers.