Effect of salt grain additions on fibrous peat consolidation

Abstract

Peat has been considered a problematic geotechnical material, with extremely high water content, low shear strength and high compressibility. Although initially high, fibrous peat undergoes dramatic reductions in permeability under compression, with secondary compression (creep) accounting for a large proportion of the settlement under loading. The key to accelerating the whole consolidation process for fibrous/hemic peats is to create a means of accelerating water flow from micropores (within the cellular structure) or humus contained in the peat. This paper presents the results of preliminary laboratory trials performed using the hydraulic consolidation (Rowe) cell apparatus to investigate a novel approach involving the addition of salt grains to fibrous peat towards accelerating its rate of primary consolidation and reducing its creep rate. Under similar loading conditions, salt-treated specimens were found to have reduced rate and magnitude of creep settlement, explained by larger volumes of micropore water expelled during primary consolidation.

Water Content Determinations for Peat and Other Organic Soils Using the Oven-Drying Method

“…According to the modified von Post peat classification system, [25] the Ballydermot peat deposit was classified as SCWPh-H 4-7 -B 3-4 -F 2 -R 2 -W 1 , the Clara peat material as SCN-H 4 -B 3 -F 3 (S)-R 1 (N)-W 1 (N), and the Derrybrien peat material as CErPh-H 3-4 -B 4 -F(Er) 2 -R(CPh) 3 -W 1. Full descriptions of these peat deposits and their geotechnical properties have been reported for the Ballydermot site by Pichan and O'Kelly [26,27] and O'Kelly and Pichan, [23] for the Clara site by O'Kelly and Zhang [28] and Zhang and O'Kelly, [29,30] and for the Derrybrien site by AGEC. [31] Refined Clara peat material (denoted by Cr) was also prepared for oven-drying tests by blending some of the remolded peat material using an electric handheld blender.…”

Discussion of “Physio-Chemical Properties, Consolidation, and Stabilization of Tropical Peat Soil Using Traditional Soil Additives — A State of the Art Literature Review” by Afnan Ahmada, Muslich Hartadi Sutantoa, Mohammed Ali Mohammed Al-Bareda, Indra Sati Hamonangan Harahapa, Seyed Vahid Alavi Nezhad Khalil Abada, Mudassir Ali Khana

“…Therefore, for assessments of the geoengineering behavior/ properties of peats and other highly organic soils, it is recommended that the emphasis of research and practice efforts should be on routine measurement of this suite of index parameters, and to move away from consistency limits testing. This holistic approach was taken, for instance, in experimental studies performed on fibric and hemic Sphagnum peats (O'Kelly and Pichan, 2014;Zhang and O'Kelly, 2015), sapric Phragmites peat, and for other highly organic fine-grained soils investigated in the paper by Li et al (2021). Note, it is mentioned here for completeness that another consensus has developed in Dutch organic soil practice, whereby it is recognized that the mainstays of correlations with strength and compressibility parameters are the water content and bulk density (see den Haan and Feddema (2013)).…”