An alternative to solve the problem of disposing dredged marine sediments (DMS) in open sea, which could lead to undesirable contamination and destruction of the marine ecosystem, is to reuse the material in reclamation works. For such applications, it is important to determine the time required for strength gain of the relocated DMS. A lab-based study was conducted to simulate and examine the post-consolidation hardening of DMS when placed as a backfill with relation to time. A separate series of tests were also carried out on the DMS being lightly solidified with cement, with the purpose of identifying potential shortening of the waiting period. The DMS sample was prepared at different water contents based on the soil's liquid limit (LL = 54.5 %), i.e. 0.90, 1.25 and 1.81LL. The undrained shear strength was measured using the laboratory vane shear (VS) test. Complementary fall cone (FC) tests were conducted for additional information on the improved remoulded strength and stiffness of the DMS. The results showed that the strength and stiffness (cone penetration resistance) of the relocated DMS could effectively improve with time, though the rest period required is shorter for a sample with lower initial water content. On the other and, light cementation shortened the rest period, and significantly improved the strength and stiffness at dosages as low as 5 % (as per dry weight of the soil). Overall the study gave an overview of the reusability of DMS as a backfill material in reclamation works, whether with or without lightly induced solidification, depending mainly on the limitations of rest period available.
Wan Salim WS, Mohd Noor NA, Sadikon SF, Arshad MF, Wahid N, Mohd Salleh S. The preliminary investigation on the dredged marine sediment of Kuala Perlis as a potential brick material. Proc. 2nd Int Conf on Biotechnology and Environment Management 2012.
Seng S, Tanaka H. Properties of very soft clays: A study of thixotropic hardening behaviour under low consolidation pressure. Soils and Foundations 2012; 52(2): 335-345.
Braja MD. Fundamentals of Geotechnical Engineering. CENGAGE Learning, UK 2013.
Malkin AY. Non-Newtonian viscosity in steady-state shear flows. J Non-Newtonian Fluid Mechanics 2013; 192: 48-65. http://dx.doi.org/10.1016/j.jnnfm.2012.09.015
Lewis J, Wagner NJ. Thixotropy. Advances in Colloid and Interface Science 2009; 147-148: 214-227. http://dx.doi.org/10.1016/j.cis.2008.09.005
Skempton AW, Northey RD. Sensitivity of clays. Geotechnique 1952; 3(1): 40-51.
Seed HB, Chan CK. Thixotropic characteristics of compacted clays. ASCE J. Soil Mechanics and Foundation Engineering 1957; 83(SM4): 1427-1435.
Horpibulsuk S, Phojan W, Suddeepong A, Chinkulkijniwat A, Liu MD. Strength development in blended cement admixed saline clay. Applied Clay Science 2012; 55: 44-52. http://dx.doi.org/10.1016/j.clay.2011.10.003
Consoli NC, Festugato L, da Rocha CG, Cruz RC. Key parameters for strength control of rammed sand-cement mixtures: Influence of types of Portland cement. Construction Building Materials 2013; 49: 591-597. http://dx.doi.org/10.1016/j.conbuildmat.2013.08.062
Chan C-M. Influence of mix uniformity on the induced solidification of dredged marine clay. Environmental Earth Sciences 2014; 71(3): 1061-1071. http://dx.doi.org/10.1007/s12665-013-2510-0
Unified Soil Classification System (USCS), in Wagner, AA. Proc. Int Conf on SMFE, (Butterworth & Co.) 1957.
British Standard Institution. British Standard BS 1377-1: Methods of test for soils for civil engineering purposes. London, UK 1990.
Japan Port and Harbour Association. Technical standard for port facilities 1999; (in Japanese).
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Copyright (c) 2014 Chee-Ming Chan, Adib Syazwan Ahmad Shakri