Experimental Analysis of Durability and Mechanical Behavior of Self-Compacting Concrete Containing Metakaolin in Sulfate Environments in order to Reduce Cement Consumption and Protect Environment

Subject Areas : New technologies in natural resources and environment

Karrar Abdul Amir Nahi ¹ , mohammad amir sherafati ^{2 *} , hadi fatemi ³

1 - Civil Engineering, Islamic Azad University, Shiraz Branch, Shiraz, Iran
2 - Assistant Professor, Department of Civil Engineering, Islamic Azad University of Shiraz
3 - Civil Engineering, Islamic Azad University, Shiraz Branch, Shiraz, Iran

Received: 2025-05-06 Accepted : 2025-06-12 Published : 2025-06-19

Keywords: cement, metakaolin, self-compacting concrete, sulfate, microstructure, sustainable development and environment,

Abstract :

Introduction: In recent years, the construction industry has been recognized as one of the largest consumers of natural resources and producers of greenhouse gases. One of the most important materials used in this industry is Portland cement, the production of which consumes significant amounts of energy and emits carbon dioxide (CO₂) one of the main greenhouse gases into the atmosphere. This issue not only affects air quality and human health but also accelerates global warming and climate change. Moreover, cement production relies heavily on raw materials such as limestone and clay, and excessive extraction of these materials leads to depletion of non-renewable natural resources and threatens environmental sustainability. Materials and Methods: This study aimed to investigate the effect of partially replacing cement with metakaolin in self-compacting concrete (SCC) and to evaluate the performance of this concrete in sulfate-rich corrosive environments. For this purpose, SCC samples were prepared with three different metakaolin replacement levels: 5%, 15%, and 25% by weight of cement. To simulate corrosive environmental conditions, samples were exposed to four sulfate solutions containing sulfate ions from sodium sulfate (Na₂SO₄), magnesium sulfate (MgSO₄), calcium sulfate (CaSO₄), and ammonium sulfate ((NH₄)₂SO₄). These sulfate ions were selected due to their destructive effects on concrete structures, particularly in industrial and marine environments, to accurately assess the concrete's resistance under realistic conditions.
	Results and Discussion: Laboratory results demonstrated that incorporating metakaolin significantly improved the characteristics of self-compacting concrete. Among the tested samples, the mixture containing 15% metakaolin exhibited the best performance. This mixture showed a notable increase in compressive strength compared to the control sample (without metakaolin). Additionally, water absorption decreased, indicating reduced porosity and increased density of the concrete microstructure. SEM images confirmed greater cohesion and fewer voids within the internal structure of the concrete. The 15% metakaolin concrete also exhibited higher resistance to sulfate environments, particularly against magnesium and ammonium ions, with less surface deterioration and cracking observed. Furthermore, the partial replacement of cement with metakaolin reduced the CO₂ emissions associated with concrete production, contributing effectively to minimizing the environmental impact of this widely used construction material. Compressive strength tests at various ages showed that the 15% metakaolin mixture performed better not only at 28 days but also at early (7 days) and late (90 days) stages, indicating good pozzolanic reactivity and long-term microstructural development. Reduced water absorption also implies lower permeability to aggressive ions, thereby decreasing long-term degradation. Stress–strain analysis showed that metakaolin-containing samples had higher stiffness (elastic modulus), reflecting increased concrete hardness and resistance to sudden deformations under cyclic loads.
Conclusion: Based on the obtained results, it can be concluded that the optimal use of 15% metakaolin not only enhances the mechanical properties and durability of self-compacting concrete against sulfate ion attack but also plays a significant role in reducing environmental pollution by lowering cement consumption. The use of metakaolin aligns with sustainable development approaches, potentially extending the service life of structures under harsh environmental conditions.

References:

1. IPCC.. Climate Change 2022: Mitigation of Climate Change. Intergovernmental Panel on Climate Change. (2022)
2. Wang, Y., Zhang, M., & Long, W.. Toward sustainable concrete: The role of supplementary cementitious materials in reducing carbon footprint. Construction and Building Materials, (2021) 270, 121371.
3. Ghasemi, T., & Ramezanianpour, A. A.. Influence of metakaolin on the durability and mechanical properties of self-compacting concrete under aggressive environments. Journal of Building Engineering, (2020) 32, 101586.
4. Soutsos, M. N., & Le, T. T.. Effect of metakaolin on concrete durability and performance. Materials and Structures, (2019)52(1), 1–13.
5. Okamura, H., & Ouchi, M.. Self-compacting concrete: development, present use and future. Journal of Advanced Concrete Technology, (2020),18(4), 141–150.
6. Bakhshi, M., & Allahverdi, A.. Sulfate attack on concrete: Mechanisms, effects and preventive strategies. Cement and Concrete Research, (2021) 146, 106449.
7. Abdollahzadeh, M., & Hosseini, S. A.. Metakaolin-based SCC: Resistance to sulfate environments and long-term performance. Journal of Cleaner Production, (2023) 381, 135188.
8. Zhang, Y., & Shi, C.. Influence of supplementary cementitious materials on the stress–strain behavior of concrete under compression. Construction and Building Materials, (2022) 314, 125677.
9. Kamyar Nabighods, Ashkan Sarada, Mohammad Mohtasham Moein, Mir Alimohammad Mirgozar Langaroudi, Juliana Byzyka, Moses Karakouzian, Evaluation of self‑compacting concrete containing pozzolan (zeolite, metakaolin & silica fume) and polypropylene fiber against sulfate attacks with different PH: an experimental study, Practice-Oriented Paper, 2023,
10. Hocine Siad, Siham Kamali-Bernard, H.A. Mesbah, G. Escadeillas, Mohamed Mouli, H. Khelafi , Characterization of the degradation of self-compacting concretes in sodium sulfate environment: Influence of different mineral admixtures, Construction and Building Materials, 2013, Volume 47, Pages 1188-1200
11- آتش بند، شهام، صابر ماهانی ، محسن، الهی حمید رضا، بررسی آزمایشگاهی اثرات سیمان ضد سولفات وترکیبات باریم بر مقاومت خاک-سیمان در محیط سولفاته ، نشریۀ زمین شناسی مهندسی 1400 ، جلد پانزدهم، شمارۀ 2
12- آدرسی، مصطفی ، مرادی باصری، حامد، مروري بر روش هاي آزمايشگاهي و تحليلي در خصوص بررسي رفتار بتن تحت حملات سولفاته و اسيدي ، فصلنامه علمي جاده ، 1402، سال بيست و يكم، دوره چهارم، شماره 117 ،
13- امیری، محمد، تنیده، پریسا، ارزیابی ریز ساختاری تاثیر محیط های سولفاته بر خواص مکانیکی بتن ژئوپلیمری، تحقیقات بتن، سال 99، سال سیزدهم شماره 2.
14- احمدی، جمال، بیگدلو ، احمد، سلیمانی راد، مهدی، تأثير استفاده از زئوليت، ميکروسيليس و متاکائولن بر کارايی و مقاومت بتن خود متراکم ، نشريه مهندسی عمران و محيط زيست 1396، جلد 74 ، شماره 3
15- انتظاری، علیرضا، اسماعیلی، جمشید، بررسی منحنی تنش وکرنش بتن سبک سازه ای غیر محصور، نشریه مهندسی عمران و محیط زیست، سال 1389، جلد 40 شماره 3.
16- حسن زاده، محسن، کیاچهر، بهفرنیا، ربانی، شهاب، بررسی تاثیر محیط سولفاته بر مقاومت فشاری ملات های حاوی پوزولان میکروسیلیس، اولین همایش ملی سازه زلزله ژئوتکنیک، سال 1389.
17- رمضانیان پور، علی اکبر ، میرولد سید سجاد، آرامون ، احسان، پیدایش، منصور، بررسي اثر چهار نوع از پوزولانهاي طبيعي ايران بر دوام بتنهاي سازه اي دربرابر حمله سولفاتي ، نشريه علمي پژوهشي اميرکبير )مهندسي عمران و محيط زيست( ، سال 1393، دوره چهل ششم، شماره 2
18- ربانی، شهاب، حسن زاده، محسن، کیاچهر، بهفرنیا، بررسی اثرپوزولان های مختلف برعملکرد ملات درمحیط سولفاته، چهارمین کنفرانس ملی ایران، 1391
19- فرخ زاد، رضا، یاسری، سجاد، انتظاریان ، محمد حسین، یاوری، امیر، بررسی تاثیرات سولفات ها بر مقاومت فشاری انواع بتن های پوزولانی و اندازه گیری میزان نفوذ با آزمون فراصوت در سنین مختلف، تحقیقات بتن 1395، سال نهم شماره اول
20- نادری، محمود، رشوند آوه، ابولفضل، صابری ورزنه، علی، بررسی پایایی بتن های خود متراکم ساخته شده از سنگ دانه¬های مختلف تحت اثر محیط سولفاته با استفاده از آزمون پیچش، مهندسی عمران، 1401، شماره 1.