Performance Evaluation of Novel Chemical Activators for Soil Stabilization by Activated Slag

Document Type : Original Research

Authors
A. H. Rafiean 1
A. Haddad 2
E. najafi kani 3
1 Semnan University
2 Faculty of Civil Engineering, Semnan University
3 Semna University
Abstract
Poorly graded sandy soil could cause numerous geotechnical problems in large areas across the world. Weak soils have insufficient bearing capacity and this may be the cause of many issues in roads infrastructure, embankments, buildings foundation, and other geotechnical projects. Stabilizing the soil by chemical stabilizers like ordinary Portland cement (OPC) is one of the most conventional methods for enhancing the engineering proprieties of soil, usually by different percentages of binder/soil ratio. Some environmental and economical issues of utilizing OPC as binder are the serious concern of researches during few decades. Alkali-activated materials (AAM), with lower destructive impact on environment and more economical profits, have been one of the attractive materials as a new generation of binders recently. These materials can be utilize in different geotechnical applications such as: soil stabilizing, different kinds of mixing method, and grouting. The current study has aimed to evaluate the mechanical and durability properties of stabilized sandy soil by AAM, the used slag for AAM binder is Ground Granulated Blast furnace Slag (GGBS) and the slag is activated by different kinds of novel alkali activators. The activators are combination of Na2SiO3 and NaOH, Na2CO3 and Ca(OH)2, and Na2SO4 and Ca(OH)2; namely, Ac1, Ac2, and Ac3, respectively. In order to evaluate mechanical properties of stabilized soil samples, unconfined compressive strength (UCS) test, and to investigate the durability properties of stabilized soil samples, freezing-thawing cycles are applied to specimens. Additionally, scanning electron microscopy (SEM) test are implemented on Ac2- and Ac3-based stabilized samples to investigate the morphological aspects of stabilized soil. Studied parameters of this study are the effect of curing time on mechanical behavior of stabilized soil samples, and the effect of types of activator on mechanical and durability properties (volume changes and soil-cement losses) of stabilized soil samples. Curing time of 14, 28, and 90 days are considered for UCS test, and 28 days are considered for freezing-thawing cycles durability test. The amount of binder for soil stabilization is considered in a constant value of 5 wt.% of dry soil for UCS and freezing-thawing tests. The 90-day UCS value for OPC-based stabilized sample is 0.75 MPa, for As1-based stabilized sample is 2.63 MPa, for As2-based stabilized sample is 2.28 MPa, and for As3-based stabilized sample is 4.5 MPa. As seen, AAM-based stabilized soil samples show greater UCS value in the same binder/soil ratio and curing time. As3 showed the most effective activator with higher UCS value as a soil stabilizer. In the test of freezing-thawing, except As2-based stabilized sample, other samples survived all 12 cycles. As2-based soil stabilized sample only survived 7 cycles of freezing and thawing. The most amount of volume changes for OPC-based stabilized soil is 12.82% for 12 cycles, while this amount is 6.65% for As2-based stabilized soil for 7 cycles. As1- and As3-based stabilized soil have showed fairly stable volume changes; i.e. with the most amounts of volume changes of 5.93% and 4.17% for 12 cycles. This results show AAM-based stabilized samples are more soundness than OPC-based stabilized samples and are more stable during volume changes.

Keywords

Subjects

1. McLellan BC, Williams RP, Lay J, et al (2011) Costs and carbon emissions for geopolymer pastes in comparison to ordinary portland cement. J Clean Prod 19:1080–1090. https://doi.org/10.1016/j.jclepro.2011.02.010
2. Li N, Shi C, Wang Q, et al (2017) Composition design and performance of alkali-activated cements. Mater Struct 50:1–11. https://doi.org/10.1617/s11527-017-1048-0
3. Mehdizadeh H, Najafi Kani E (2018) Rheology and apparent activation energy of alkali activated phosphorous slag. Constr Build Mater 171:197–204. https://doi.org/10.1016/j.conbuildmat.2018.03.130
4. Hausmann MR (1990) Engineering principles of ground modification. McGraw-Hill
5. Davidovits PJ (2002) 30 Years of Successes and Failures in Geopolymer Applications . Market Trends and Potential Breakthroughs . 1–16
6. Najafi E, Allahverdi A, Provis JL (2012) Efflorescence control in geopolymer binders based on natural pozzolan. Cem Concr Compos 34:25–33. https://doi.org/10.1016/j.cemconcomp.2011.07.007
7. Ghadir P, Ranjbar N (2018) Clayey soil stabilization using geopolymer and Portland cement. Constr Build Mater 188:361–371. https://doi.org/10.1016/j.conbuildmat.2018.07.207
8. Allahverdi A, Najafi Kani E (2009) Construction wastes as raw materials for geopolymer binders. Int J Civ Eng 7:154–160
9. Alsafi S, Farzadnia N, Asadi A, Kim B (2017) Collapsibility potential of gypseous soil stabilized with fly ash geopolymer ; characterization and assessment. 137:390–409. https://doi.org/10.1016/j.conbuildmat.2017.01.079
10. Liu Z, Asce SM, Cai CS, et al (2014) Feasibility Study of Loess Stabilization with Fly Ash – Based Geopolymer. 1–8. https://doi.org/10.1061/(ASCE)MT.1943-5533.0001490.
11. Sargent P, Hughes PN, Rouainia M, White ML (2013) The use of alkali activated waste binders in enhancing the mechanical properties and durability of soft alluvial soils. Eng Geol 152:96–108. https://doi.org/10.1016/j.enggeo.2012.10.013
12. Yi Y, Li C, Liu S, Asce M (2010) Alkali-Activated Ground-Granulated Blast Furnace Slag for Stabilization of Marine Soft Clay. J Materail Civ Eng 11:246–250. https://doi.org/10.1061/(ASCE)MT.1943-5533.0001100.
13. Yi Y, Gu L, Liu S (2015) Microstructural and mechanical properties of marine soft clay stabilized by lime-activated ground granulated blastfurnace slag. Appl Clay Sci 103:71–76. https://doi.org/10.1016/j.clay.2014.11.005
14. Yi Y, Asce SM, Liska M, Al-tabbaa A (2014) Properties of Two Model Soils Stabilized with Different Blends and Contents of GGBS , MgO , Lime , and PC. 267–274. https://doi.org/10.1061/(ASCE)MT.1943-5533.0000806.
15. Du Y, Yu B, Liu K, et al (2015) Physical , Hydraulic , and Mechanical Properties of Clayey Soil Stabilized by Lightweight Alkali-Activated Slag Geopolymer. 1–10. https://doi.org/10.1061/(ASCE)MT.1943-5533
16. Yu B-W, Du Y-J, Jin F, Liu C-Y (2016) Multiscale Study of Sodium Sulfate Soaking Durability of Low Plastic Clay Stabilized by Reactive Magnesia-Activated Ground Granulated Blast-Furnace Slag. J Mater Civ Eng 28:04016016. https://doi.org/10.1061/(ASCE)MT.1943-5533.0001517
17. Lloyd RR, Provis JL, Van Deventer JSJ (2009) Microscopy and microanalysis of inorganic polymer cements. 1: Remnant fly ash particles. J Mater Sci 44:608–619. https://doi.org/10.1007/s10853-008-3077-0
18. Cristelo N, Glendinning S, Fernandes L, Pinto AT (2012) Effect of calcium content on soil stabilisation with alkaline activation. Constr Build Mater 29:167–174. https://doi.org/10.1016/j.conbuildmat.2011.10.049
Modares Civil Engineering journal
Volume 20, Issue 2
May and June 2020
Pages 41-54