A method for considering curing temperature effect in mix proportion design of mass cement-solidified mud at high water content

Conventional mix proportion design of cement-solidified mud (CSM) used as fill material is usually based on the past experience in Japan. Nevertheless, the actual field curing temperature ( T ) of a new CSM project can be quite different from the Japan’s case, particularly in a different climate zone. As a consequence, Japan’s experience possibly leads to inappropriate design of mix proportion, because the strength gain of cementitious material is strongly influenced by T . This paper aims to provide an insight into this issue. First, 20 different mixes of CSM are prepared and cured under different temperatures varying from 5 to 40 °C, and the unconfined compressive strengths ( q u ) at various curing ages are measured for each mix cured under each temperature. It is found that for CSM a higher T constantly produces not only very much higher early-age q u but also substantially higher long-term q u , and this can be attributed to 2 aspects, i.e. the accelerated rate of chemical reactions and the larger extent of pozzolanic reactions. Second, a characterization model is developed to quantify the curing temperature effect on the strength gain of CSM, and its reasonability is well demonstrated by a large number of verification data series. Third, in conjunction with an actual project in Singapore, 2 companion sets of UCTs, namely on laboratory-prepared specimens and in situ cored samples, are conducted to identify the difference between field and laboratory strength developments. The value of field/laboratory strength ratio β , a key design parameter, obtained in Singapore’s case is then compared against the Japanese recommendation. Results indicate that the value of β obtained in Singapore’s case is significantly larger than the value recommended in Japan as there is an evident difference in the field curing temperature between these two countries. This suggests that the curing temperature affects the mix proportion design of CSM to a large extent. Finally, a novel procedure on how to approximately consider the curing temperature effect in the mix proportion design of mass CSM is proposed for the reference of practitioners.