Sustainable improvement of soft marine clay using low cement content: A multi-scale experimental investigation Usama Khalid, C.C. Liao ⇑ , Guan-lin Ye, Santosh Kumar Yadav Department of Civil Engineering, State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, China highlights  Effect of low cement content is significant on macro and micro structure of soft clay.  The fundamental parameters relationships for low and highly cemented clays are established.  This study can be helpful for the low cement-treated dredged clays land reclamation projects. article info Article history: Received 12 June 2018 Received in revised form 27 September 2018 Accepted 4 October 2018 Keywords: Low cemented clay Compressibility Stress-strain behavior Stress path Microstructure Empirical models abstract The sustainable utilization of dredged soft clays for land reclamation requires a lower strength with lesser cement content as compared to traditional cement-treated clays. The mechanical behavior of soft clays at low cement content can differ from clays treated with higher content. For land reclamation, the required cement content is generally used up to 10%. Hence, this study is focused on analyzing the sustainable uti- lization of soft clays treated with cement content lower than 7%. Additionally, a comparison is drawn between a low-cement-treated soft clay with the highly cemented clays to determine the difference in mechanical behavior. Shanghai soft clay is reconstituted with cement content from 0 to 6%. The experi- mental investigation indicates that the low cement content has a significant effect on the microstructure, compression characteristics, compressive strength, undrained stress paths, and stress-strain behavior. However, the effect of curing time on such characteristics is limited. The mechanical behavior of low- cement-treated soft clay is similar to the highly cemented clays with respect to the relationships of com- pressive strength with strain at failure, yield stress and clay-water/cement ratio but is different with respect to deformation modulus versus compressive strength. The outcomes of this study can help to choose the minimum required cement content for the fill materials of land reclamation projects. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction Large volumes of dredged materials (DMs) are produced during the construction and maintenance of marine infrastructures. Just in Shanghai, the generation of DMs exceeds 70 million m 3 annually, and >2.5 billion m 3 of DMs have already been dumped into the sur- rounding ocean [1]. Dumping of DMs has become a challenge due to the unavailability of new disposal sites in the ocean or on land. A sustainable solution is to use DMs as cement-treated fills for land reclamation. The DM is a very soft clay with low shear strength (c u < 50 kPa) and higher natural water content than the liquid limit. For land reclamation, the required cement content is usually not >10% [2]. Its required strength is much lesser than the tradi- tional cement-treated soils and the strength development rate is lower at low cement content [3]. The strength development rate with the increment of cement content is divided into four zones; the inactive zone (Zone I), clay-cement interaction zone (Zone II), transitional zone (Zone III), and the cement-clay interaction zone (Zone IV) [3]. The bound- ary values of these zones vary with the types of clay and cement used. The boundaries of Zones I and II are normally in the range 10–15% and up to 50% respectively [4,6]. Zones of cement- treated clays with respect to strength development rate are in Fig. 1. Zone I is not fully inactive and some effect of the cement content can be expected on geotechnical characteristics [4]. The influence of cement content on strength within Zone I is quite dif- ferent from that within Zone II [5]. A vast amount of research work has been conducted within Zone II to examine the mechanical behavior and microstructural characteristics of cement-treated soft clays in the past [3,6–13]. The range of cement content covered https://doi.org/10.1016/j.conbuildmat.2018.10.034 0950-0618/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: billaday@sjtu.edu.cn (C.C. Liao). Construction and Building Materials 191 (2018) 469–480 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat