Use of elevated curing temperature for accelerated testing of cement stabilized dredged Singapore marine clay

Yi-Tan Lu, Thiam-Soon Tan, Kok-Kwang Phoon

In the proceedings of: GEO2011: 64th Canadian Geotechnical Conference, 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, 5th Pan-American Conference on Teaching and Learning of Geotechnical Engineering

Session: Ground Improvement/Remediation

ABSTRACT: Cement stabilized Singapore marine clay is the material associated with the Stabilized Dredged Fill (SDF) technology practiced in Singapore. A novel accelerated curing/testing procedure is proposed in this study making use of a constant temperature hot water bath. The accelerated testing technique enables the later-age strength (7-day strength in this study) of the SDF material to be forecasted at a very early curing age (~30 hrs). Laboratory samples are prepared by mixing Singapore upper marine clay at high water content with Portland blast furnace cement. The mixes are designed to reflect the actual constituent proportions on the site. Samples are cured in a hot water bath at 60 ºC for 24 hrs followed by 6 hrs of cooling. Unconfined compression tests and bender element tests are conducted on specimens cured under both accelerated condition (30 hrs) and normal room temperature condition (7 days). Test results show that both the unconfined compressive strength (UCS) and the small-strain shear stiffness (Gmax) are controlled by the water/cement ratio in either curing condition. Accelerated UCS after 30 hrs of curing can be used to predict 7-day UCS, although it may over-predict by 20%. In addition to the strength-to-strength correlation, stiffness-to-stiffness and strength-to-stiffness correlations are also established between the two conditions. As effective quality control requires early determination of the material later-age strength, these correlations may be used to improve the current SDF quality control.

RÉSUMÉ: LSDF être prévue à un âge très précoce de durcissement (~30 heures). du ciment de haut fourneau. Les mélanges sont conçus pour refléter les proportions des constituants réels sur le site. Les échantillons sont remédiés ºC pendant 24 heures suivie par 6 heures de refroidissement. Essais de compression simple et des essais de languettes piézocéramiques sont effectués sur des échantillons durcis sous la condition accélérée (30 heures) et la condition normale de température ambiante (7 jours). Les résultats des essais indiqués que la résistance en compression simple («UCS») et le module de cisaillement à faible déformation («Gmax») UCS accélérée après 30 heures jours, même s corrélations de résistance-à-résistance, les corrélations de rigidité-à-rigidité et résistance-à-rigidité sont établies entre les deux conditions de durcissement. Comme contrôle de la qualité efficace exige une détermination rapide de la résistance de

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