Service life of concrete

Technical Report · Wed Nov 01 04:00:00 EST 1989

OSTI ID:5435809

Clifton, J R; Knab, L I ^[1]

---

1. National Inst. of Standards and Technology, Gaithersburg, MD (USA)

The US Nuclear Regulatory Commission (NRC) has the responsibility for developing a strategy for the disposal of low-level radioactive waste (LLW). An approach being considered for their disposal is to place the waste forms in concrete vaults buried in the earth. A service life of 500 years is required for the concrete vaults as they may be left unattended for much of their lives. This report examines the basis for making service life predictions based on accelerated testing and mathematical modeling of factors controlling the durability of concrete buried in the ground. Degradation processes are analyzed based on considerations of their occurrence, extent of potential damage, and mechanisms. A recommended research plan for developing methods for predicting the service life of concrete is presented. The major degradation processes that concrete of underground vaults will likely encounter are sulfate attack, corrosion of reinforcing steel, alkali-aggregate reactions, and leaching by ground water. Freezing and thawing damage could occur before the vaults are covered with soil and therefore are addressed. Other degradation processes which may occur are microbiological attack, salt crystallization, and attack by LLW, especially by acidic materials. Two important factors controlling the resistance of concrete to these degradation processes are its quality and permeability. Concepts of quality and factors affecting quality of concrete are discussed. Permeability is discussed in terms of the water-to-cement ratio, the pore structure of concrete, and the effects of cracks. 101 refs., 15 figs., 5 tabs.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (USA). Div. of Engineering; National Inst. of Standards and Technology, Gaithersburg, MD (USA)
• Sponsoring Organization: NRC
• OSTI ID: 5435809
• Report Number(s): NUREG/CR-5466; NISTIR--89-4086; ON: TI90003156
• Country of Publication: United States
• Language: English

Related Subjects

052002* -- Nuclear Fuels-- Waste Disposal & Storage
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
36 MATERIALS SCIENCE
360603 -- Materials-- Properties
360604 -- Materials-- Corrosion
Erosion
& Degradation
BUILDING MATERIALS
CHEMICAL REACTIONS
CONCRETES
CORROSION
DISSOLUTION
HYDROGEN COMPOUNDS
LEACHING
LOW-LEVEL RADIOACTIVE WASTES
MANAGEMENT
MATERIALS
OXYGEN COMPOUNDS
PERMEABILITY
POROSITY
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTES
REINFORCED CONCRETE
REINFORCED MATERIALS
SEAWATER
SEPARATION PROCESSES
SERVICE LIFE
SULFATES
SULFUR COMPOUNDS
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WATER