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RESEARCH PAPER UDC 666.97
DOI: 10.22227/1997-0935.2021.10.1357-1362
Impact of impurities of local construction materials on the bearing capacity of the concrete used in structures in Burundi
Emmanuel Mikerego, Nestor Niyonzima, Jean Claude Ntirampeba
University of Burundi; Bujumbura, Burundi
ABSTRACT
Introduction. The article is about an assessment of the impact of impurities contained in the local construction materials on the mechanical characteristics of the concrete used in reinforced concrete structures in Burundi.
Materials and methods. The methodology of the study consisted in varying the quantity of impurities for the manufacturing of the concrete experimental cubic samples. The grain sizes of the studied ordinary concrete were in the favourable zones according to the recommended granulometry for standard concretes. Simulation of impurities was made by adding in the mixing water solid particles taken from a local rock called "red earth". The particles were composed by (24 %) of clays, (38 %) of silts and (38 %) of sands. As for the used cement in this study, it was the type CEM I (32.5). The quantities of impurities were expressed in grams per litre of mixing water (g/l) and were varying from (0 g/l) to (100 g/l) with a step of (20 g/l). The prepared experimental concrete samples were stored in the laboratory of materials at the University of Burundi and were subjected to compression testing under hydraulic press after 28 days.
Results. The impact of impurities consisting of (24 %) of clays, (38 %) of silts and (38 %) of sands is identified. Each increase of (20 g) of impurities in a litre of mixing water induces an average decrease of (4 %) on the compressive strength and the Young's modulus for an ordinary concrete.
Conclusions. The impact of impurities contained in the local construction materials used in the manufacturing of the con- O <t crete for reinforced concrete structures in Burundi is studied. Each increase of (20 g) of impurities in a litre of mixing water n 2 induces an average decrease of (4 %) on the compressive strength and the Young's modulus of an ordinary concrete. For k | Burundi, a curve for the approximation of the bearing capacity of the concrete used in reinforced concrete structures ac- _ K cording to the quantity of impurities contained in the local construction materials was established. Hence, it is advisable to G r start by the specification of the quantity of impurities contained in the construction materials before making the concrete for W ^ reinforced concrete structures in order to predict the mechanical performances of the concrete used in reinforced concrete • y structures. MI
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KEYWORDS: impurities, local construction materials in Burundi, reinforced concrete structures h z
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FOR CITATION: Mikerego E., Niyonzima N., Ntirampeba J.C. Impact of impurities of local construction materials on the o 7 bearing capacity of the concrete used in structures in Burundi. Vestnik MGSU [Monthly Journal on Construction and Archi- 0 ° tecture]. 2021; 16(10):1357-1362. DOI: 10.22227/1997-0935.2021.10.1357-1362 < 3
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Corresponding author: Mikerego Emmanuel, mikeregoemmanuel@hotmail.com. C r
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Влияние примесей местных строительных материалов на несущую способность бетона, используемого в составе конструкций на территории Бурунди
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Эммануэль Микерего, Нестор Нийонзима, Жан Клод Нтирампеба и §
Университет Бурунди; г. Бужумбура, Бурунди ф )
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Введение. Оценивается влияние примесей местных строительных материалов на механические характеристики 3 1
бетона, используемого для изготовления железобетонных конструкций в Бурунди. 1 О)
Материалы и методы. Методика исследования заключается в изменении количества примесей при эксперимен- . И
тальном изготовлении образцов бетона кубической формы. Размеры зернистого заполнителя изучаемого стандарт- у □
ного бетона не должны выходить за пределы рекомендованных значений для гранулометрического состава стандарт- (Я с
ных бетонов. Моделирование примесей осуществлялось путем введения в воду затворения твердых частиц местной О я
породы под названием «красная земля». В состав частиц примесей входят глины (24 %), ил (38 %) и песок (38 %). 1 1
Использовался цемент марки СЕМ I (32,5). Количество примесей выражалось в граммах на литр воды затворения О О
(г/л) и варьировалось от 0 до 100 г/л с шагом в 20 г/л. Приготовленные экспериментальные образцы бетона хранились 0 0
в лаборатории материалов Университета Бурунди и по истечении 28 суток подвергались испытаниям на сжатие с по- мм мощью гидравлического пресса.
© Emmanuel Mikerego, Nestor Niyonzima, Jean Claude Ntirampeba, 2021 Распространяется на основании Creative Commons Attribution Non-Commercial (CC BY-NC)
Результаты. Установлено влияние примесей, в состав которых входят глины (24 %), ил (38 %) и песок (38 %). Каждый раз с ростом количества примесей на 20 г на литр воды затворения сокращается прочность стандартного бетона на сжатие в среднем на 4 %, а также падает значение модуля Юнга.
Выводы. Начерчена кривая приблизительной величины несущей способности бетона, применяемого для изготовления железобетонных конструкций, в зависимости от количества примесей в составе местных строительных материалов. Перед началом изготовления бетона, предназначенного для железобетонных конструкций, следует указывать количество примесей в составе строительных материалов для обеспечения возможности прогнозирования механических показателей бетона.
КЛЮЧЕВЫЕ СЛОВА: примеси, местные строительные материалы из Бурунди, железобетонные конструкции
ДЛЯ ЦИТИРОВАНИЯ: МикерегоЭ., Нийонзима Н., НтирампебаЖ.К. Impact of impurities of local construction materials on the bearing capacity of the concrete used in structures in Burundi // Вестник МГСУ. 2021. Т. 16. Вып. 10. С. 1357-1362. DOI: 10.22227/1997-0935.2021.10.1357-1362
Автор, ответственный за переписку: Эммануэль Микерего, mikeregoemmanuel@hotmail.com.
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INTRODUCTION
In Burundi, the local construction materials are not generally washed before being used in the manufacturing of the concrete for reinforced concrete structures. The materials are generally river-borne and quarries. Even the mixing water used is usually taken from rivers. As an example, in the large city of Burundi, Bujumbura, various rivers flowing through the city are the main sources of construction materials and mixing water. Therefore, the sources of construction materials make them contain impurities. For example, the quantity of impurities depends on the rainfall and the exploitation of the catchment areas throughout the year for river aggregates [1-4].
Foreign literature [5-8] show that the impurities contained in the construction materials for concrete have an impact on the mechanical characteristics of the concrete made for the reinforced concrete structures. Except the known effect of the water/cement ratios on the compressive strength of the concrete [9], is also known that the impurities contained in the construction materials make worse the mechanical characteristics of the concrete used in the reinforced concrete structures. In [10-12], the source and quality of the mixing water used were found to have an impact on the mechanical performances of the concrete. The impact of impurities contained in sea, ocean and waste water on the mechanical properties of the concrete used in structures is confirmed in [13-19].
Although there are studies on the impact of impurities contained in the construction materials in foreign literature, in Burundi, the impact of impurities contained in the local construction materials on the concrete used in reinforced concrete structures is unknown.
MATERIALS AND METHODS
In this paper, the studied impurities come from the aggregates used during the fabrication of the concrete for structures in Burundi. However, the study does not exclude that the impurities may also come from the mixing water used. In this study, the guiding hypothesis is that the impurities contained in the aggregates always
end up suspended in the mixing water whether it is clean or not.
Thus, the methodology of the study consists in varying the quantity of impurities in the mixing water used for the manufacturing of the experimental concrete cubic (10 x 10 x 10 cm) samples. The concrete studied is the ordinary with fine and coarse aggregates from the Ntahangwa River. The sizes of the grain aggregates were in the favourable zones according to the recommended granulometry for the standard concrete.
If expressed per cubic metre, the concrete was made from (207 litre) of water, (400 kg) of cement, (590 kg) of sand and (1169 kg) of gravel. As for the particles simulating the impurities in the mixing water, they were taken from a local rock called "red earth" from Karama in the commune of Isare in Bujumbura province. These impurities were classified as silt nature as indicated by the reading on the Taylor triangular chart used in the classification of the nature of soils. They were composed by (24 %) of clays, (38 %) of silts and (38 %) of sands, as shown by the Casagrande sedimentation particle size analysis. In addition, the cement used in this study was of the type CEM I (32.5).
The quantities of impurities were expressed in grams per litre of mixing water (g/l) and they were varying from (0 g/l) to (100 g/l) with a step of (20 g/l). For each experimental design, nine (9) samples of experimental concrete were prepared (Fig. 1).
Fig. 1. The powder simulating impurities (a) and the concrete mix design (b) for the preparation of the experimental concrete samples (c) in the laboratory
The prepared experimental concrete samples were stored in the laboratory of materials at the University of Burundi and were subjected to compression testing under an hydraulic press after 28 days (Fig. 2).
C. 1357-1362
Fig. 2. The experimental concrete samples (a) and the process of crushing an experimental concrete sample (b) under an hydraulic press in the laboratory
The results from the experimental tests were collected in tables designed to allow an easy analysis and
discussion. For the facilitation of the interpretation, the obtained results were limited to the quantity of (220 g) of impurities in a litre of mixing water.
RESULTS OF THE RESEARCH
In this study, it was understood that the studied impurities come from the aggregates and water carried by the rivers or from the quarries. Compression tests applied on the experimental concrete samples show that the studied impurities decrease significantly the compressive strength of the concrete (Fig. 3).
The increase of impurities in the construction materials makes worse the mechanical characteristics of the concrete. Each variation of 20 grams of impurities contained in a litre of mixing water induces an average decrease of (4 %) in the compressive strength of an ordinary concrete (Fig. 4).
Quantity of impurities in a litre of mixing water.
Fig. 3. Results of the compression tests applied on the experimental concrete samples under the hydraulic press
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Fig. 4. Diagram of the decrease of the compressive strength for an ordinary concrete due to impurities contained in the constituents materials
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Fig. 5. Diagram of the decrease of Young's modulus for an ordinary concrete due to impurities contained in the constituents materials
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Fig. 6. Diagram of the decrease of the bearing capacity of the concrete of the reinforced concrete structures according to the quantity of impurities contained in the local construction materials in Burundi
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Similarly, each variation of 20 grams of impurities contained in a litre of mixing water induces an average decrease of (4 %) of the Young's modulus for an ordinary concrete (Fig. 5).
Finally, the obtained results show the decrease in percentage of the bearing capacity of the concrete of reinforced concrete structures due to the impurities contained in the local construction materials in Burundi (Fig. 6).
CONCLUSION AND DISCUSSION
In this study, the impact of impurities contained in the local construction materials in Burundi are simulated and evaluated. The studied impurities consisted of (24 %)
of clays, (38 %) of silts and (38 %) of sands. Each increase of (20 g) of impurities in a litre of mixing water was found to induce an average decrease of (4 %) on the compressive strength and the Young's modulus for an ordinary concrete. For Burundi, a curve for the approximation of the bearing capacity of the concrete used in reinforced concrete structures in function of the quantity of impurities contained in local construction materials was established. Hence, it is advisable to start by the specification of the quantity of impurities contained in the construction materials before making the concrete for reinforced concrete structures in order to predict the mechanical performances of the concrete used in reinforced concrete structures.
С. 1357-1362
REFERENCES / СПИСОК ИСТОЧНИКОВ
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Received August 28, 2021.
Adopted in revised form on October 22, 2021.
Approved for publication on October 22, 2021.
B io n о t e s : Emmanuel Mikerego — Doctor (Ph.D.) in Engineering, Lecturer of the Faculty of Engineering Sciences; University of Burundi; B.P 2700, Bujumbura, Burundi; ORCID: 0000-0002-5743-6476; mikeregoemmanuel@ hotmail.com;
Nestor Niyonzima — Doctor (Ph.D.) in Engineering, Lecturer of the Faculty of Engineering Sciences; University of Burundi; B.P 2700, Bujumbura, Burundi; Nestor.niyonzima@ub.edu.bi;
Jean Claude Ntirampeba—master student ofEngineering Sciences; University of Burundi; B.P2700, Bujumbura, Burundi; jntirampeba@gmail.com.
Contribution of the authors:
Mikerego E. — conceptualization, methodology, data processing, writing of the article, scientific editing of the
text.
11. Obi Lawrence E. Empirical investigation of the effects of water quality on concrete compressive strength. International Journal of Constructive Research in Civil Engineering. 2016; 2(5):30-35. DOI: 10.20431/2454-8693.0205006
12. Dadhich P.N., Sharma R.K., Shekhawat S., Jain C., Gopal B. Impact of water quality on compressive strength of reinforced concrete. International Journal ofEngineering Research & Technology. 2014; 3(03).
13. Wegian F.M. Effect of seawater for mixing and curing on structural concrete. The IES Journal Part A: Civil & Structural Engineering. 2010; 3(4):235-243. DOI: 10.1080/19373260.2010.521048
14. Taylor M.A., Kuwairi A. Effects of ocean salts on the compressive strength of concrete. Cement and Concrete Research. 2978; 8(4):492-500. DOI: 10.1016/0008-8846(78)90029-7
15. Olugbenga A.T.A. Effects of different sources of water on concrete stress: A case study of Ile-Ife. Civil and Environmental Research. 2014; 6:39-43.
16. Al-Jabri K.S., Al-Saidy A.H., Taha R., Al-Ke-myani A.J. Effect of using Wastewater on the properties of high strength concrete. Procedia Engineering. 2011; 14:370-376. DOI: 10.1016/j.proeng.2011.07.046
17. Farid H., Mansoor M.S., Shah S.A.R., Khan N.M., Shabbir R.M.F., Adnan M. et al. Impact analysis of water quality on the development of construction materials. Processes. 2019; 7(9):579. DOI: 10.3390/ pr7090579
18. Wasserman B. Wash water in the mix: effects on the compressive strength of concrete. International Journal of Construction Education and Research. 2012; 8(4):301-316. DOI: 10.1080/15578771.2011.633974
19. Ayodele F.O., Ayeni I.S. Analysis of influence of silt/clay impurities present in fine aggregates on the compressive strength of concrete. International Journal of Engineering Research and Science and Technology. 2015; 15(4):6.
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Niyonzima N. — conceptualization, writing of the article.
Ntirampeba J.C. — conceptualization, data gathering and processing.
The authors declare no conflict of interest.
Поступила в редакцию 28 августа 2021 г.
Принята в доработанном виде 22 октября 2021 г.
Одобрена для публикации 22 октября 2021 г.
Об авторах : Эммануэль Микерего — доктор технических наук, преподаватель факультета инженерных наук; Университет Бурунди; B.P 2700, г. Бужумбура, Бурунди; ORCID: 0000-0002-5743-6476; mikeregoemmanuel@hotmail.com;
Нестор Нийонзима — доктор технических наук, преподаватель факультета инженерных наук; Университет Бурунди; B.P 2700, г. Бужумбура, Бурунди; Nestor.niyonzima@ub.edu.bi;
Жан Клод Нтирампеба — студент магистратуры технических наук; Университет Бурунди; B.P 2700, г Бужумбура, Бурунди; jntirampeba@gmail.com.
Вклад авторов:
Микерего Э. — концептуализация, методология, обработка данных, написание статьи, научное редактирование текста.
Нийонзима Н. — концептуализация, написание статьи.
Нтирампеба Ж.К. — концептуализация, сбор и обработка данных.
Авторы заявляют об отсутствии конфликта интересов.
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