California Bearing Ratio of a Reactive Clay Treated with Nano-Additives and Cement

AbstractPlastic clays in subgrade may cause major engineering defects such as excessive heave or settlement during the wet season that contribute to the formation of uneven geometry at the pavement surface. Soil stabilization is often a requisite to ameliorate the engineering properties of soft soil...

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Bibliographic Details
Published in:Journal of materials in civil engineering 2022-02, Vol.34 (2)
Main Authors: Karimiazar, Jafar, Sharifi Teshnizi, Ebrahim, Mirzababaei, Mehdi, Mahdad, Masoud, Arjmandzadeh, Reza
Format: Article
Language:English
Subjects:
Additives
Aluminum oxide
Building materials
Calcium aluminate
Calcium silicate hydrate
California bearing ratio
Cement
Civil engineering
Clay
Penetration tests
Photomicrographs
Rainy season
Silicon dioxide
Soft soils
Soil compaction
Soil investigations
Soil properties
Soil stabilization
Technical Papers
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Summary:AbstractPlastic clays in subgrade may cause major engineering defects such as excessive heave or settlement during the wet season that contribute to the formation of uneven geometry at the pavement surface. Soil stabilization is often a requisite to ameliorate the engineering properties of soft soils or reactive clays. This study investigates the application of nano-silica and nano-alumina to improve the California bearing ratio (CBR) of a local clay. The clay was treated with cement (2%–8%), with nano-additive (0.1%–1.5%) and with cement and nano-additive (3% cement + 0.1%–1.5% nano-additive). The compacted sample was cured for 7 days and subjected to soaked and unsoaked CBR tests. The soaked CBR of the nontreated clay increased by 49% and 27% for 1% nano-silica and 1% nano-alumina treated clay, respectively. Although 3% cement addition improved the CBR of the soaked clay by 28%, the combination of 3% cement with 1% nano-silica and nano-alumina resulted in 196% and 164% increase in the soaked CBR of the nontreated clay, respectively. The combination of nano-additives and cement yielded the same soaked CBR as if 6%–7% cement would have been used. Clay treated with 1% nano-silica and 3% cement achieved the highest CBR value within the tested samples and the sample treated with 1% nano-alumina and 3% cement achieved the lowest free swell potential. The scanning electron microscopy (SEM) micrographs of the treated clay showed the formation of uniform fabric with fewer pore spaces and calcium silicate hydrate (CSH)/calcium aluminate hydrate (CAH) products within the fabric of nano-additive treated clay.
ISSN:0899-1561
1943-5533
DOI:10.1061/(ASCE)MT.1943-5533.0004028