Tools for assessing damage in concrete affected by AAR coming from fine and coarse aggregates
Over the last few years, comprehensive management programs for the diagnosis and prognosis of alkali-aggregate reaction (AAR) in aging concrete structures were developed in North America, based on a series of laboratory test procedures. Although promising, these lab-procedures presented several parameters whose impacts were not completely understood, which significantly reduced their applicability for the appraisal of deteriorated concrete structures in service. In this context, it has been suggested that two lab-tools, the Stiffness Damage Test (SDT) and the Damage Rating Index (DRI) could reliably assess the condition of concrete affected by AAR. This paper presents the condition assessment of 25, 35 and 45 MPa AAR affected concrete specimens incorporating fine and coarse reactive aggregates and presenting different distress degrees (i.e. expansion levels from 0.05 to 0.30%) through the use of an innovative multi-level approach. Results show that both SDT and DRI are suitable for assessing damage in AAR affected concrete through their output parameters. Yet, they present a complementary character, which illustrates the need for a multi-level approach.
TOWARDS QUANTIFICATION OF MICROSTRUCTURAL DAMAGE IN AAR DETERIORATED CONCRETE. FRACTURE OF CONCRETE AND ROCK: RECENT DEVELOPMENTS. PAPERS PRESENTED AT THE INTERNATIONAL CONFERENCE, UNIVERSITY OF WALES, COLLEGE OF CARDIFF, SCHOOL OF ENGINEERING, SEPTEMBER 20-22, 1989
For the structural appraisal and cost effective management of alkali aggregate reaction (AAR) damaged structures, Mott MacDonald have developed a range of physical testing techniques on concrete cores. One such test, the Stiffness Damage Test, is aimed at giving a quantitative assessment of the amount of microstructural damage within a concrete core. This is a non-destructive stress/strain measuring technique to provide a measure of concrete material damage which can be related to compressive and tensile strength changes, tree expansion to date, and petrographical changes. This paper reports the development of this technique, and compares it with more traditional strength tests.(A) For the covering abstract of the conference see IRRD 829348.
PASSIVE AND LOW-ENERGY RESEARCH AND PRACTICES-DEHUMIDIFICATION
Methods of achieving acceptable indoor conditions in overheated, temperate, and underheated humid climates are discussed and compared. Desiccants and desiccant systems utilizing solid and liquid sorbents and various low-energy mechanical systems are described and evaluated.