International Concrete Abstracts Portal

SP-228CD This CD-ROM of Special Publication 228 contains the papers presented at the Seventh International Symposium on the Utilization of High-Strength/High- Performance Concrete that was held in Washington, D.C., USA, June 20-24, 2005. The symposium continued the success of previous symposia held in Stavanger, Norway, (1987); Berkeley, California (1990); Lillehammer, Norway, (1993); Paris, France, (1996); Sandefjord, Norway, (1999); and Leipzig, Germany, (2002). The symposium brought together engineers and material scientists from around the world to discuss topics ranging from the latest applications to the most recent research on high-strength and high-performance concrete. In the years since the first symposium was held in Stavanger, there has been worldwide growth in the use of both high-strength and high-performance concrete. In addition to more research and applications of traditional types of high-performance concrete, the use of self-consolidating concrete and ultra-high-performance concrete has moved from the laboratory to practical applications. This publication offers the opportunity to learn the latest about these developments.

LCPC (Central Laboratory for Roads and Bridges, a French public research laboratory) has developed for five years a new concept of concrete pavement. It is based upon the following ideas: - High-Performance Concrete shows unique qualities with regard to pavement applications, like high tensile strength, durability, freeze-thaw resistance, abrasion resistance and prevention of steel corrosion; - but economy does not promote the use of HPC in conventional pavement, since the gain in flexural strength leads to a decrease in slab thickness, which does not compensate the increase of material unit cost (i.e. the cost per unit surface increases when replacing normal- by high-strength concrete); - HPC qualities are mostly desirable at the top surface of the pavement. Therefore, HPC Carpet consists in a thin, 60-mm HPC wearing course, reinforced by a welded wire mesh, cast upon a conventional concrete (or cement-treated material) structural layer. Thanks to a complex of polymer and geotextile, there is no bond between the two layers, so that reflexive cracking from the base to the course layer is avoided. However, cracking due to traffic loads is permitted in both directions, the dense reinforcement being supposed to maintain the course layer integrity. The paper will give an overview of this research, which encompassed design calculations, thermal instability verification, fatigue tests on a 10-m full scale model and an experimental construction site near Lyon (France). Here, a 120-m long test section has been built in 2003, and is currently submitted to a heavy truck traffic. To date, the behavior is excellent. In conclusion, the economical potential of this new concept will be highlighted. Rehabilitation of old concrete pavements – where slabs are partly cracked, with moderate rocking – appears as a promising market.

This paper describes an approach used in developing a performance-based mixture design and optimization system for paving concrete. This system is being developed as part of a Federal Highway Administration (FHWA) project entitled “Computer-Based Guidelines for Job-Specific Optimization of Paving Concrete.” In this project, a new method of designing and optimizing concrete mixtures for pavement applications is being developed. The procedure includes two key elements: a knowledge base and mixture optimization routines. The former assists the user in selecting mixture design criteria based on site-specific conditions. It also allows for the user to quickly identify what combinations of concrete-making materials may be a starting-point for their site-specific conditions. The second element allows the user to optimize numerous properties of their concrete mixture including: w/cm ratio, cement content, the use of chemical and mineral admixtures, and gradation of aggregates. The optimization can be based on a variety of targets including cost, strength, workability, durability, and numerous other concrete mixture properties – both fundamental and phenomenological. Overall optimization of the selected targets is achieved using concepts of utility theory. When combined, these methods represent a rational approach to quantifying subjective decision-making criteria that is used in finding the optimum concrete mixture for specific conditions.

This study deals first with the deterioration of glass fiber in mortar due to the alkali of cement and how to improve the deterioration of the glass fiber in mortar using special admixture of blast furnace fume (BFF). The deterioration is estimated by an accelerated test for flexural strength of mortar stored in water at 80 °C for 3 weeks. Secondly, the deterioration of mortar due to sulfuric acid attack using blast furnace fume(BFF) is investigated. Dust collected from the top of Chinese small-sized iron blast furnaces is called BFF in Japan , and is used as admixture for high strength concrete in China. BFF is composed of very fine particles with spherical shape. Its average grain size is several micrometers in diameter. Test results of this first study shows that the deterioration of glass fiber in mortar due to alkali is not improved by using BFF alone but is significantly improved by using both BFF and blast furnace slag (BFS) or silica fume (SF). Concerning acid attack, it is found that the deterioration of mortar in dilute sulfuric acid is significantly decreased by using both of BFF and BFS or SF.

Chemical attack poses a serious problem for concrete structures in severe environments. This investigation deals with exposure of high strength/high performance concrete to sulfate attack in a controlled environment. Experimental tests consisted of measuring the compressive strength, tensile strength and modulus of elasticity after 3 years of exposure to corrosive conditions consisting of chemical solutions containing 1%(NH4)2SO4 and 2%(NH4)2SO4.