Clays as SCM – Reactivity of Uncalcined Kaolinite and Bentonite, and Impact on Phase Assemblage and Strength Development of PC Mortars

Geiker, Mette Rica; Gallucci, Emmanuel

doi:10.2478/ncr-2019-0006

Abstract

The impact of substitution of cement paste with uncalcined clay (bentonite and kaolinite) in the range of 5% by volume of paste on the development of hydration and properties of mortar was investigated. Two issues were addressed, the expected filler effect of the dispersed sub-micron clay particles, and the possible chemical reactivity of the clay.

The study indicated that Portland cement paste may be modified by addition of well dispersed clay and that the impact includes accelerated cement hydration as well as altered distribution of products. Compressive strength development was accelerated, but later age strength was reduced, especially for the bentonite mixes. In contrast, microscopic porosity measurements indicated no detrimental impact on the coarse capillary porosity.

The investigation indicates that for durability related engineering properties, the application of uncalcined clay might be a potential means for reduction of the clinker factor in concrete in support of sustainability.

References

1. Scrivener KL, John VM, Gartner EM: “Eco-efficient cements. Potential, economically viable solutions for a low-CO₂, cement-based materials industry.” In United Nations Environment Program, Paris, France, 2016, 64 pp.10.1016/j.cemconres.2018.03.015
Search in Google Scholar Back to article
2. Damtoft JS, Lukasik J, Herfort D, Sorrentino D, Gartner EM: ”Sustainable development and climate change initiatives”. Cement and Concrete Research, Vol. 38, No. 2, 2008, pp. 115-127.10.1016/j.cemconres.2007.09.008
Open DOI Search in Google Scholar Back to article
3. Lothenbach B, Scrivener K and Hooton RD: “Supplementary cementitious materials”. Cement and Concrete Research, Vol. 41, No. 12, 2011, pp. 1244-1256.10.1016/j.cemconres.2010.12.001
Open DOI Search in Google Scholar Back to article
4. Kocaba V: “Development and evaluation of methods to follow microstructural development of cementitious systems including slags”, PhD thesis, EPFL-TH4523, EPFL, Laboratoire des Matériaux de Construction, Lausanne, Switzerland, 2009, 263 pp.
Search in Google Scholar Back to article
5. Fernandez Lopez R: “Calcined clayey soils as a potential replacement for cement in developing countries”. PhD thesis, EPFL-TH4302, EPFL, Laboratoire des Matériaux de Construction, Lausanne, Switzerland, 2009, 178 pp. 29
Search in Google Scholar Back to article
6. Krøyer H, Lindgreen H, Jakobsen HJ, Skibsted J: “Hydration of Portland cement in the presence of clay minerals studied by 29Si and 27Al MAS NMR spectroscopy”. Advances in Cement Research, Vol. 15, No. 3, 2003, pp. 103-112.10.1680/adcr.2003.15.3.103
Open DOI Search in Google Scholar Back to article
7. Lindgreen H, Geiker M, Krøyer H, Springer N, Skibsted J H: “Microstructure engineering of Portland cement pastes and mortars through addition of ultrafine layer silicates”. Cement and Concrete Composites, Vol. 30, No. 8, 2008, pp. 686-699.10.1016/j.cemconcomp.2008.05.003
Open DOI Search in Google Scholar Back to article
8. Kjeldsen AM: “New Concretes through addition of layer silicates. Bentonite clay soprtion.” Personal communication, 2003.
Search in Google Scholar Back to article
9. Lindgreen HB, Jakobsen HJ, Geiker MR, Stang H, Krøyer H, Skibsted JB: “Suspension of clays in water for addition to e.g. concrete”. Patent WO2008052554A1, 2008-05-08.
Search in Google Scholar Back to article
10. EN 196-1. Methods of testing cement - Part 1: Determination of strength, 2005.
Search in Google Scholar Back to article
11. EN 1015-03. Determination of consistence of fresh mortar (by flow table), 2004
Search in Google Scholar Back to article
12. NordTest, NT Build 492, “Concrete, mortar and cement-based repair materials: chloride migration coefficient from non-steady-state migration experiments”, approved 1999-11.
Search in Google Scholar Back to article
13. Fontenay le Sage de C, Sellevold EJ: “Ice formation in hardened cement pastes – I. Mature water-saturated pastes”, Durability of building materials and components, ASTM STP 691, 1980.
Search in Google Scholar Back to article
14. Bager D & Sellevold EJ: “Ice formation in hardened cement paste, Part I – Room temperature cured pastes”, Cement and Concrete Research, Vol. 16, 1986, pp. 709–20.10.1016/0008-8846(86)90045-1
Open DOI Search in Google Scholar Back to article
15. Sellevold EJ & Bager D: “Low temperature calorimetry as a pore structure probe”, Proceedings, 7^th International Congress on the Chemistry of Cement, Paris, vol. 4; 1981.
Search in Google Scholar Back to article
16. Osbæck B: “The influence of air content by assessing the pozzolanic activity of fly ash by strength testing”. Cement and Concrete Research, Vol. 15, No. 1, 1985. pp. 53-64.10.1016/0008-8846(85)90008-0
Search in Google Scholar Back to article
17. Wu, M, Fridh K, Johannesson B & Geiker M: “Impact of sample crushing on porosity characterization of hardened cement pastes by low temperature calorimetry: Comparison of powder and cylinder samples.” Thermochimica Acta, Vol. 665, 2018, pp. 11-19.10.1016/j.tca.2018.05.002
Search in Google Scholar Back to article

Clays as SCM – Reactivity of Uncalcined Kaolinite and Bentonite, and Impact on Phase Assemblage and Strength Development of PC Mortars

Abstract

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