Characterization of Laboratory Prepared Concrete Pastes Exposed to High Alkaline and High Sodium Salt Solutions

Langton, C. A.¹ 

[1] Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

关键词: concrete durability;    alkali silica reaction;    saltstone disposal unit;    SDU concrete;   

DOI  :  10.2172/1305137
RP-ID  :  SRNL-STI--2016-00214
PID  :  OSTI ID: 1305137

美国|英语

来源: SciTech Connect

【 摘 要 】

The objective of this study was to identify potential chemical degradation mechanisms for the Saltstone Disposal Unit (SDU) concretes, which over the performance life of the structures may be exposed to highly alkaline sodium salt solutions containing sulfate, hydroxide, and other potentially corrosive chemicals in salt solution and saltstone flush water, drain water, leachate and / or pore solution. The samples analyzed in this study were cement pastes prepared in the SIMCO Technologies, Inc. concrete laboratory. They were based on the paste fractions of the concretes used to construct the Saltstone Disposal Units (SDUs). SDU 1 and 4 concrete pastes were represented by the PV1 test specimens. The paste in the SDU 2, 3, 5, and 6 concrete was represented by the PV2 test specimens. SIMCO Technologies, Inc. selected the chemicals and proportions in the aggressive solutions to approximate proportions in the saltstone pore solution [2, 3, 5, and 6]. These test specimens were cured for 56 days in curing chamber before being immersed in aggressive solutions. After exposure, the samples were frozen to prevent additional chemical transport and reaction. Selected archived (retrieved from the freezer) samples were sent to the Savannah River National Laboratory (SRNL) for additional characterization using x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray (EDX) spectroscopy. Characterization results are summarized in this report. In addition, a correlation between the oxide composition of the pastes and their chemical durability in the alkaline salt solutions is provided.