Mechanical properties and degradation mechanism of LNG containment concrete material under cryogenic conditions

Abstract

• Compressive strength and tensile strength of the concretes at cryogenic temperature were studied. • The damage degree of the concretes after cryogenic freezing-thawing cycles was investigated. • The mechanism of mechanical properties of the concretes at cryogenic temperatures was analyzed. • The degradation mechanism of damaged concrete under freezing-thawing cycles was discussed. • Application of the HCC for on all-concrete LNG storage tanks is appropriate. The mechanical properties and deterioration of concrete under cryogenic conditions are unclear. Here, high-strength and cryogenic temperature-resistant concrete (HCC) was developed for Liquefied natural gas (LNG) inner tank applications. Influences including compressive and tensile concrete strength under different temperatures (25 °C ∼ -165 °C) and freezing-thawing cycles were investigated. The results showed that lower temperatures result in higher compressive strengths, the tensile strength increases and then decreases, and the greatest increase in strength occurs at −45 °C. The tensile strength of HCC and C60 concrete decreases below −105 °C and −45 °C, respectively; more freezing-thawing cycles result in greater mechanical property degradation. Furthermore, compared to C60 concrete, HCC has a significantly lower rate of strength loss. The mechanical property mechanisms at different cryogenic temperatures and deterioration due to the freezing-thawing cycles were investigated by differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). HCC is an ideal material for LNG inner tanks.