Strength estimation method for arbitrary age of cement-treated soil based on high-temperature curing history
Hiroyuki Hara, Yugo Shirabe
Abstract
The type and amount of cement required for the cement-treatment method, a widely used countermeasure against soft grounds, are determined in advance through laboratory mixing tests. Generally, mixing tests reveal the strength of materials with an age of at least four weeks. In many cases, however, this time period is not available during the construction process. Therefore, technology must be developed that can shorten the time required for these mixing tests. In the present study, high-temperature curing was performed to strengthen cement-treated soil; this strategy was used to develop a method for long-term strength estimation. For this purpose, unconfined compression tests and thermogravimetric analyses were performed on cement-treated soils cured at 20, 30, 40, and 55 °C for specified periods of time. The results revealed that the effect of the temperature-induced acceleration of strength development could be accurately evaluated using the equivalent material age in accordance with the Arrhenius law. Furthermore, specimens with an equivalent material age exhibited comparable strengths as well as hydration reaction rates, regardless of the curing temperature. Based on these results, the unconfined compression test results were leveraged under two different temperature conditions to obtain the activation energy expressing the acceleration effect of strength development. A method was proposed to estimate the strength of cement-treated soil of an arbitrary material age in a short period of time. Notably, the proposed method offers higher estimation accuracy at lower curing temperatures. The difference between the estimated and measured values was within 10%, on average, under the combined temperature condition yielding the highest estimation accuracy.