بررسی عملکرد فعال‌کننده ‌های شیمیایی نوین برای تثبیت خاک با استفاده از سرباره فعال ‌شده با قلیا

نوع مقاله : پژوهشی اصیل (کامل)

نویسندگان
امیر حسین رفیعیان 1
عبدالحسین حداد 2
ابراهیم نجفی کانی 1
1 دانشگاه سمنان
2 عضو هیات علمی دانشگاه سمنان
چکیده
این پژوهش پارامترهای مکانیکی و دوام خاک ماسه‏ای تثبیت ‏شده با سرباره فعال‏شده توسط قلیا را به صورت آزمایشگاهی بررسی کرده است. ماده پایه چسباننده استفاده شده در این پژوهش سرباره کوره‏ ذوب آهن‏ است که به میزان 5 درصد وزن خاک خشک استفاده شده است. برای تثبیت خاک از سه نوع چسباننده به نام‏های اختصاری Ac1، Ac2، و Ac3 استفاده شده است. چسباننده Ac1 ترکیبی از سدیم هیدروکسید و سدیم سیلیکات و سرباره، چسباننده Ac2 ترکیبی از سدیم کربنات و کلسیم هیدروکسید و سرباره، و چسباننده Ac3 ترکیبی از سدیم سولفات و کلسیم هیدروکسید و سرباره می‏باشند. نتایج حاصل از این نمونه‏ها با نمونه ‏های تثبیت‏شده به وسیله‏ ی سیمان پرتلند مقایسه شده است. نمونه ‏های خاک تثبیت‏ شده با سیمان پرتلند به صورت SOPC ، و نمونه‏ های تثبیت‏ شده با چسباننده‏ های Ac1، Ac2 و Ac3 به ترتیب SGAc1، SGAc2، و SGAc3 نام‏گذاری شده‏اند. آزمایش‏های مقاومت فشاری تک‏محوری، چرخه‏های ذوب و یخبندان و تصویربرداری میکروسکوپ الکترونی روی نمونه‏های تثبیت شده با این چسباننده ‏ها انجام شده است. نتایج این پژوهش نشان داد که چسباننده Ac3 در مقایسه با سایر چسباننده‏های پیشنهادی عملکرد بهتری را از نظر پارامترهای مقاومتی و دوام ارائه داد.. در آزمایش مقاومت فشاری تک‏ محوری خاک تثبیت‏شده با سیمان پرتلند مقاومت 75/0 مگاپاسکال و خاک تثبیت‏شده با چسباننده‏ های Ac1 ، Ac2 ، و Ac3 به ترتیب مقاومت 63/2، 28/2، و 5/4 مگاپاسکال را کسب نمودند. همچنین نتایج آزمایش چرخه‏ های ذوب و یخبندان نشان داد نمونه ‏های تثبیت‏ شده با چسباننده‏ های پیشنهادی از ثبات حجمی و دوام مناسبی برخوردارند. بیشترین میزان تغییرات حجمی که نمونه‏ های SOPC، SGAc1، SGAc2، و SGAc3 پس از 12 سیکل به ترتیب برابر 82/12، 93/5، 65/6، و 17/4 درصد است.

کلیدواژه‌ها

موضوعات

عنوان مقاله English

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

نویسندگان English

Amir Hossein Rafiean 1
Abdolhosein Haddad 2
ebrahim najafi kani 1
1 Semnan University
2 Faculty of Civil Engineering, Semnan University
چکیده English

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.

کلیدواژه‌ها English

Soil stabilization
Ordinary Portland Cement
Alkali-Activated Material
Alkali Activator
Mechanical properties
durability
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مهندسی عمران مدرس
دوره 20، شماره 2
خرداد و تیر 1399
صفحه 41-54