Iraqi bentonite as natural pozzolan
In this study, Iraqi high-calcium bentonite was used for the first time to prepare natural pozzolan for concrete by the thermal activation method (calcination). Raw bentonite was calcined at 700, 750, 800, 850, 900, and 950°C for 30, 60, 90, and 120 minutes at each temperature. X-ray diffraction and...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Peter the Great St. Petersburg Polytechnic University
2022-12-01
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| Series: | Magazine of Civil Engineering |
| Subjects: | |
| Online Access: | http://engstroy.spbstu.ru/article/2022.116.04/ |
| _version_ | 1797948913361092608 |
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| author | Al-Hammood Amer Frayyeh Qais Abbas Waleed |
| author_facet | Al-Hammood Amer Frayyeh Qais Abbas Waleed |
| author_sort | Al-Hammood Amer |
| collection | DOAJ |
| description | In this study, Iraqi high-calcium bentonite was used for the first time to prepare natural pozzolan for concrete by the thermal activation method (calcination). Raw bentonite was calcined at 700, 750, 800, 850, 900, and 950°C for 30, 60, 90, and 120 minutes at each temperature. X-ray diffraction and quantitative X-ray diffraction techniques identified the optimal calcination program at 800°C for 90 minutes. In this program, calcination destroyed the crystal structure of bentonite-forming clay minerals, thus converting silicon, aluminium, and iron oxides into chemically reactive amorphous phases. The prepared natural pozzolan achieves a strength activity index of 108.3% at 28 days; additionally, it meets the requirements of the Iraqi specification of pozzolanic materials. The effects of Portland cement replacement with calcined bentonite at 5, 10, 15, 20, 25, and 30% were studied on selected properties of the cementitious binder and concrete. The results indicate that replacement percentage is positively associated with initial and final setting times and negatively correlated with the concrete slump. At seven days, calcined bentonite causes the decline of the compressive strength of concrete, while at 28 days, concretes containing 5, 10, and 15% develop higher compressive strength than the control mix. However, the compressive strength of concretes containing calcined bentonite differs from the control mix by not more than ±9% at 90 days. Calcined bentonite reduces the concrete splitting strength and density properties, and the absorption at 25% substitution or less. |
| first_indexed | 2024-04-10T21:51:00Z |
| format | Article |
| id | doaj.art-3895ce4840c9414896b8fdf0ccf1db18 |
| institution | Directory Open Access Journal |
| issn | 2712-8172 |
| language | English |
| last_indexed | 2024-04-10T21:51:00Z |
| publishDate | 2022-12-01 |
| publisher | Peter the Great St. Petersburg Polytechnic University |
| record_format | Article |
| series | Magazine of Civil Engineering |
| spelling | doaj.art-3895ce4840c9414896b8fdf0ccf1db182023-01-18T12:46:52ZengPeter the Great St. Petersburg Polytechnic UniversityMagazine of Civil Engineering2712-81722022-12-011160810.34910/MCE.116.420714726Iraqi bentonite as natural pozzolanAl-Hammood Amer0https://orcid.org/0000-0001-6361-7153Frayyeh Qais1https://orcid.org/0000-0002-3667-0191Abbas Waleed2https://orcid.org/0000-0001-8287-2782University of TechnologyUniversity of Technology - IraqUniversity of Technology - IraqIn this study, Iraqi high-calcium bentonite was used for the first time to prepare natural pozzolan for concrete by the thermal activation method (calcination). Raw bentonite was calcined at 700, 750, 800, 850, 900, and 950°C for 30, 60, 90, and 120 minutes at each temperature. X-ray diffraction and quantitative X-ray diffraction techniques identified the optimal calcination program at 800°C for 90 minutes. In this program, calcination destroyed the crystal structure of bentonite-forming clay minerals, thus converting silicon, aluminium, and iron oxides into chemically reactive amorphous phases. The prepared natural pozzolan achieves a strength activity index of 108.3% at 28 days; additionally, it meets the requirements of the Iraqi specification of pozzolanic materials. The effects of Portland cement replacement with calcined bentonite at 5, 10, 15, 20, 25, and 30% were studied on selected properties of the cementitious binder and concrete. The results indicate that replacement percentage is positively associated with initial and final setting times and negatively correlated with the concrete slump. At seven days, calcined bentonite causes the decline of the compressive strength of concrete, while at 28 days, concretes containing 5, 10, and 15% develop higher compressive strength than the control mix. However, the compressive strength of concretes containing calcined bentonite differs from the control mix by not more than ±9% at 90 days. Calcined bentonite reduces the concrete splitting strength and density properties, and the absorption at 25% substitution or less.http://engstroy.spbstu.ru/article/2022.116.04/concretebentonitemontmorillonitethermal activationcalcined claycementitious materialspozzolancompressive strengthstrength activity indextensile strengthfresh propertieswater absorptionx-ray diffractionquantitative xrd |
| spellingShingle | Al-Hammood Amer Frayyeh Qais Abbas Waleed Iraqi bentonite as natural pozzolan Magazine of Civil Engineering concrete bentonite montmorillonite thermal activation calcined clay cementitious materials pozzolan compressive strength strength activity index tensile strength fresh properties water absorption x-ray diffraction quantitative xrd |
| title | Iraqi bentonite as natural pozzolan |
| title_full | Iraqi bentonite as natural pozzolan |
| title_fullStr | Iraqi bentonite as natural pozzolan |
| title_full_unstemmed | Iraqi bentonite as natural pozzolan |
| title_short | Iraqi bentonite as natural pozzolan |
| title_sort | iraqi bentonite as natural pozzolan |
| topic | concrete bentonite montmorillonite thermal activation calcined clay cementitious materials pozzolan compressive strength strength activity index tensile strength fresh properties water absorption x-ray diffraction quantitative xrd |
| url | http://engstroy.spbstu.ru/article/2022.116.04/ |
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