Volume 18 (2016) Article 16

Geotechnical properties of peat soil stabilised with shredded waste tyre chips in combination with gypsum, lime or cement.

by M. Saberian and M.A. Rahgozar

Published online: 03.07.2016

Summary

Peat has a high content of water and organic substances. These weak components can cause low bearing capacity and high consolidation settlement under load, which means that peat deposits must usually be stabilised if they are to bear constructions such as buildings or roads. In this study we investigated the performance of waste tyre chips (10 % by weight) and sand (400 kg m^-3) supplemented with a pozzolanic binder (gypsum, lime or cement) at a range of dosages (5 %, 10 % or 15 % by weight) as a stabiliser for peat soil. Peat samples were taken from a fen peatland at Chaghakhor Wetland in Chahar Mahal and Bakhtiari Province, Iran. In total, 162 test specimens were prepared and subjected to laboratory strength testing (unconfined compression test and direct shear test). Additionally, the pH of each admixture was recorded immediately after mixing, elemental compositions were determined by X-Ray Fluorescence (XRF), and structures were examined using Scanning Electron Microscopy (SEM). It was observed that: (1) the total percentage of pozzolanic compounds in the peat soil was well below the minimum of 70 % set by the standard ASTM C 618 (ASTM 2000), so an additive such as cement, lime or gypsum would certainly be required; (2) specimens stabilised with gypsum or lime showed improvements in unconfined compressive strength (UCS), but those stabilised with ordinary Portland cement exhibited the greatest improvement in UCS (up to 12,200 %) as well as improvements in the direct shear parameters c and ?; (3) according to the XRF tests, additives such as cement, lime and gypsum introduced considerable amounts of Si, Al, Ca and O, which are important for pozzolanic reactions in peat soils; and (4) on the basis of the results of UCS and direct shear tests, the optimum percentage of the additives tested would be 5 %.

Citation

Saberian, M. & Rahgozar, M.A. (2016): Geotechnical properties of peat soil stabilised with shredded waste tyre chips in combination with gypsum, lime or cement. Mires and Peat, 18(16), 1-16. (Online: http://www.mires-and-peat.net/pages/volumes/map18/map1816.php); 10.19189/MaP.2015.OMB.211

Reviewers

IMCG and IPS acknowledge the work of the reviewers.