Monitoring Alkali-Silica Reaction Significance in Nuclear Concrete Structural Members

Abstract

A large-scale testing program on alkali silica reaction (ASR)-affected concrete structural members without shear reinforcement representative of structural members found in nuclear power plants is presented. Three concrete specimens, designed to experience a free expansion rate of approximately 0.15% per year were fabricated and placed within a controlled environmental chamber (38 ± 1 o C (100 ± 2 o F) and 95 ± 5% relative humidity (RH)). Sixty-four (64) embedded transducers and twelve (12) long-gauge fiber-optic sensors provide evidence of strong anisotropic expansion and oriented ASR-induced cracking resulting from the confinement effect caused by the reinforcement layout and additional structural boundary conditions. Surface cracking is not indicative of internal ASR-induced damage/expansion. 2. Large-scale testing program 2.1 Test specimens The structural specimen detail was designed to closely

Damage Mechanism Evaluation of Large-Scale Concrete Structures Affected by Alkali-Silica Reaction Using Acoustic Emission

“…The main difference between the specimens was using of NaOH or LiNO 3 . In the reactive specimens, 9.8 kg/m 3 NaOH solution was added, while in the control specimen 1.9 kg/m 3 LiNO 3 was included in the mixture [22].…”

“…Additionally, a 30% lithium nitrate solution was added to the control specimens to mitigate the ASR effect. More details regarding concrete mixture design was presented by Hayes et al [22].…”

“…A 1.5 mm layer of polyethylene was employed between the concrete and the steel frame in the confined specimen to reduce friction. More detailed information about the specimens and steel frame design were presented in Hayes, et al [22]. In this experiment, the specimens stand on four short, steel columns (76 cm height) to provide access to the bottom of the specimens.…”

“…After casting, the specimen surfaces were sprayed with curing compound and covered with wet burlap and plastic sheets to reduce moisture loss and cracks from shrinkage during drying. The burlap was kept wet until chamber construction was complete [22].…”

“…The chamber was equipped with systems that kept the specimens at the environmental temperature of 38 ± 1 • C and humidity of 95% ± 5%. The environmental chamber was initiated 26 days after casting and operated continuously except for shutdown for measurements and inspections [22].…”