Effect of preparation methods on strength and microstructural properties of cemented marine clay

• Published in: Construction & building materials 2019-12, Vol.227, p.116690, Article 116690
• Main Author: Ekinci, Abdullah
• Format: Article
• Language: English
• Subjects: Cementation; Cemented marine clay; Embodied energy; Grind compaction; In situ compaction; Marine clay microstructure; Ped compaction; Scanning electron microscopy; Unconfined compression test
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2019.116690

•Peds mimics the site compaction and produces strengths close to in situ strength.•The peds present in the matrix retain the in-situ structure to some extent.•Pores in ped-compaction do not contribute to chemical reactions to boost strength gain.•Ped-compacted cemented marine clay leads to reduction in total embodied energy.•Ped-compaction can be used in minor road subbase, rammed earth wall, and structural fill. The engineering community realizes that it is incumbent to identify an alternative soil disposal or reuse solution owing to the financial and environmental problems associated with current techniques. To identify such an alternative, this study examines the strength and microstructural properties of marine clay-cemented mixes, using two extreme preparation methods to understand which sample preparation technique better mimics the in situ behavior of the mix; further, it proposes a solution that is both environment friendly and economical. To this end, three marine clay specimens were produced through cementation and subjected to in situ grinding and ped-compaction in an unconfined compression test to evaluate the structure of the specimens. Furthermore, scanning electron microscopy was conducted to analyze the microstructure formed in the ped and ground specimens due to cementation. Results revealed that finely ground marine clay offered a homogeneous mixing opportunity that led to reduced pore space and allowed the following four discrete processes to be conducted—cation exchange, flocculation and agglomeration, cement hydration, and pozzolanic reaction. These processes further increased the strength of the marine clay to approximately three times that of the ped-compacted specimen. Nevertheless, ped compaction still achieved strengths similar to in situ clay strength, which satisfies the strength requirements of applications such as minor road subbase, rammed earth wall, and structural fill. Furthermore, the proposed solution resulted in a reduction of embodied energy, effort required for compaction to specific unit weight, and energy consumption of grinding process; thereby reducing carbon foot print and overall costs.