Creep of concrete as influenced by the rate of expansion due to alkali–silica reaction

Abstract

Three alkali-sensitive and one insensitive aggregate were used in the concrete mixes. The slow reacting aggregates were greywacke from the Lower Harz, quartz porphyry from Halle and crushed gravel from the Upper Rhine valley. The insensitive aggregate was quartz porphyry from the Black Forest. The concretes showed the typical S-shaped expansion curve in the 40 C fog room. After a certain time in the fog room, specimens were taken out and creep tests were conducted in a climate of 80% RH and 23 C. This scenario does not necessarily reproduce the situation of real structures but helps to understand the influence of ASR expansion development on creep. The creep deformation depended clearly on the preceding storage duration in the fog chamber. The largest influence on the deformation appeared at the time when the expansion rate in the fog room had a maximum.

Zustandserfassung von Betonfahrbahndecken mit Verdacht auf eine schädigende Alkali‐Kieselsäure‐Reaktion

“…Unter Einwirkung alkalihaltiger Enteisungsmittel sowie in Kombination mit zyklischen Beanspruchungen wird der AKR‐bedingte Schädigungsprozess verstärkt. Die Schädigung führt im Vergleich zu schadensfreien Betonen zur Verringerung mechanischer und bruchmechanischer Betoneigenschaften , deren Ursache bei einer Alkali‐Kieselsäure‐Reaktion u. a. in der Abnahme der Steifigkeit alkaliempfindlicher Gesteinskörnungen zu finden ist .…”