The author details the reactions of various concretes on steel reinforcement. Although portland cements, slag cements and high alumina cements are all hydraulic binders, each possess special properties which are examined. The discussion of causes and methods of preventing the corrosion of steel reinforcement covers such aspects as galvanised steel reinforcement, effects of concrete composition, corrosion of steel reinforcments in concrete and prestressed reinforcement. It is concluded that the most significant influences on the corrosion of prestressing wire in concrete are: the presence of chloride; the presence of nitrates; the composition of the concrete; the degree of carbonation of the concrete; concrete compaction and, chlorides and sulphates should be used as far as possible when steel is embedded. (TRRL)

Corrosion of steel by concrete

Damage-plastic model for concrete failure

This paper summarizes the results of an investigation on objective modeling and prediction of deformation localization in nonlinear force-based frame elements. Emphasis is placed on the behavior of reinforced concrete structures where localization is most likely to occur. The discussion begins with a brief review of the force-based element formulation. Next, plastic hinge behavior is classified into three categories: hardening plastic hinges, perfectly plastic hinges, and softening plastic hinges. The three types of inelastic behavior pose an increasing challenge to objective postpeak modeling. The physical and numerical characteristics of localized failure are outlined. Two regularization techniques for maintaining postpeak objectivity are proposed: (1) a constant fracture energy criterion, which provides objective response on the element force-displacement level; and (2) geometric scaling, which provides objective response on the local moment-curvature level in plastic hinge regions. The discussion conc...

Localization Issues in Force-Based Frame Elements

The term Ultra-High Performance Concrete (UHPC) refers to a relatively new class of advanced cementitious composite materials whose mechanical and durability properties far surpass those of conventional concrete. This class of concrete has been demonstrated to facilitate solutions that address specific problems in the United States highway bridge infrastructure. Initial material development research on UHPC began more than two decades ago. First structural deployments began in the late 1990s. First field deployments in the U.S. highway transportation infrastructure began in 2006. For this study, UHPC-class materials are defined as cementitious-based composite materials with discontinuous fiber reinforcement that exhibit compressive strength above 21.7 ksi (150 MPa), pre- and post-cracking tensile strength above 0.72 ksi (5 MPa), and enhanced durability via a discontinuous pore structure. This report documents the state of the art with regard to the research, development, and deployment of UHPC components within the U.S. highway transportation infrastructure. More than 600 technical articles and reports covering research and applications using UHPC have been published in English in the last 20 years, with many more published in other languages. The report includes information about materials and production, mechanical properties, structural design and structural testing, durability and durability testing, and actual and potential applications. The report concludes with recommendations for the future direction for UHPC applications in the United States.

https://rosap.ntl.bts.gov/view/dot/26387/dot_26387_DS1.pdf

Ultra-High Performance Concrete: A State-of-the-Art Report for the Bridge Community

Shape and Size Effects on the Compressive Strength of High-strength Concrete

Softening of concrete in compression — Localization and size effects

fib Bulletin 34. Model Code for Service Life Design

Guide for the use of stainless steel reinforcement in concrete structures

In service life predictions of concrete structures in marine environment, the critical chloride content is a crucial parameter However, there is a lack of reliable data for this parameter This paper presents a statistical model for the critical chloride content derived from measurements based on corrosion sensors installed in a 37 years old jetty For each corrosion sensor location, the chloride content at different sensor rings is found from the chloride profile obtained from detailed profile grinding of the concrete core drilled out before installation of each sensor The critical chloride content for each sensor location is then obtained by comparing the chloride profile with the sensor reading at the depth of depassivation Further, the influence of the critical chloride content on the calculated service life is studied From the probabilistic service life calculations, it is found that the service life increases from 50 to 100 years if the characteristic value of the critical chloride content increases from 034 to 067% (by weight of cement)

Critical chloride content and its influence on service life predictions

The apparent chloride diffusion coefficient derived by evaluating chloride profiles using Fick’s 2 nd law of diffusion is found to be time dependent and may decrease considerably with increasing age of the concrete. In service life predictions of marine structures this time dependency of the diffusion coefficient is taken into account by an age factor. However, reliable data for this age factor are limited. Field studies on concrete exposed to marine environment have been conducted in Norway over the last three decades in order to investigate the time dependency of the apparent chloride diffusion coefficient. This paper presents results from some of these field studies. To illustrate the sensitivity of the age factor in service life calculations, a numerical study is performed using a probabilistic approach.

Gro Markeset

Papers

Softening of concrete in compression — Localization and size effects

fib Bulletin 34. Model Code for Service Life Design

Guide for the use of stainless steel reinforcement in concrete structures

Critical chloride content and its influence on service life predictions

Time dependent chloride diffusion coefficient : field studies of concrete exposed to marine environment in Norway