Influence of Kaolinite Content on Performance of Limestone-Calcined Clay-Cement

doi:10.16552/j.cnki.issn1001-1625.2025.0489

Abstract

Abstract: Two calcined clay minerals (namely coal gangue and metakaolin) were blended to adjust the kaolinite content in calcined clay. This process was employed to prepare limestone-calcined clay-cement (LC³) with 50% (mass fraction) clinker content. The mechanical property and hydration product evolution of LC³ with calcined clay containing 20% to 90% (mass fraction) kaolinite were investigated using a variety of analytical techniques, including compressive strength tests, hydration exothermic analysis, X-ray diffraction (XRD), thermogravimetric analysis (TG), and thermodynamic simulations. The results show that the increase of kaolinite content promotes the reaction between calcium carbonate and aluminate in calcined clay, and consumes calcium hydroxide and ettringite generated during the hydration of cement clinker. When the content of kaolinite increases from 20% to 60%, the mechanical properties of LC³ gradually increase, and the 28 d compressive strength increases by 33.99%. The amount of C-(A)-S-H gel, ettringite and carboaluminate in hydration products increases, and the degree of clinker reaction decreases from 89.09% to 82.08%. When the kaolinite content exceeds 60%, with the further increase of kaolinite content, the decrease of clinker reaction degree and the increase of compressive strength obviously slow down, and the 28 d compressive strength only increases by 2.77 MPa. The content of carboaluminate in hydration products increases, but the increase is relatively limited. At the same time, the thermodynamic simulation results show that the content of C-(A)-S-H gel decreases.

Key words: limestone-calcined clay-cement, coal gangue, kaolin, mechanical property, hydration product

CLC Number:

TU525.9

WANG Qing, SHAN Rui, LI Tianru, ZHANG Qiang, CHENG Yang, ZHAO Mingyu. Influence of Kaolinite Content on Performance of Limestone-Calcined Clay-Cement[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2025, 44(12): 4406-4412.

References

[1] MILLER S A, JOHN V M, PACCA S A, et al. Carbon dioxide reduction potential in the global cement industry by 2050[J]. Cement and Concrete Research, 2018, 114: 115-124.
[2] SCRIVENER K, AVET F, MARAGHECHI H, et al. Impacting factors and properties of limestone calcined clay cements (LC³)[J]. Green Materials, 2019, 7(1): 3-14.
[3] SUI H, HOU P K, LIU Y M, et al. Limestone calcined clay cement: mechanical properties, crystallography, and microstructure development[J]. Journal of Sustainable Cement-Based Materials, 2023, 12(4): 427-440.
[4] MSINJILI N S, GLUTH G J G, STURM P, et al. Comparison of calcined illitic clays (brick clays) and low-grade kaolinitic clays as supplementary cementitious materials[J]. Materials and Structures, 2019, 52(5): 94.
[5] TANG J, WEI S F, LI W F, et al. Synergistic effect of metakaolin and limestone on the hydration properties of Portland cement[J]. Construction and Building Materials, 2019, 223: 177-184.
[6] ZUNINO F, SCRIVENER K. The reaction between metakaolin and limestone and its effect in porosity refinement and mechanical properties[J]. Cement and Concrete Research, 2021, 140: 106307.
[7] RUDIĆ O, UKRAINCZYK N, KRÜGER M, et al. Efficiency of limestone in clinker-reduced binders: consideration of water-binder ratio, capillary porosity and compressive strength[J]. Construction and Building Materials, 2023, 386: 131594.
[8] ZUNINO F, SCRIVENER K. Reactivity of kaolinitic clays calcined in the 650~1 050 ℃ temperature range: towards a robust assessment of overcalcination[J]. Cement and Concrete Composites, 2024, 146: 105380.
[9] ZHAO Y H, ZHANG Y D. A review on hydration process and setting time of limestone calcined clay cement (LC³) [J]. Solids, 2023, 4(1): 24-38.
[10] NOSHEEN B, KHURAM R, IDREES Z, et al. Prioritization of low-grade kaolin and mixed clays for performance evaluation of limestone calcined clay cement (LC³): multi-criteria assessment [J]. Applied Clay Science, 2023, 243: 107080.
[11] FERNANDEZ R, MARTIRENA F, SCRIVENER K L. The origin of the pozzolanic activity of calcined clay minerals: a comparison between kaolinite, illite and montmorillonite[J]. Cement and Concrete Research, 2011, 41(1): 113-122.
[12] ZUNINO F, SCRIVENER K. The influence of the filler effect on the sulfate requirement of blended cements[J]. Cement and Concrete Research, 2019, 126: 105918.
[13] YU K Y, LIU Y S, JIA M J, et al. Thermal energy storage cement mortar containing encapsulated hydrated salt/fly ash cenosphere phase change material: thermo-mechanical properties and energy saving analysis[J]. Journal of Energy Storage, 2022, 51: 104388.
[14] ABDELAZIZ G E, SHOUKRY H, SELIM A A, et al. Recent progress in limestone-calcined clay cement (LC³): a review[J]. Materials Science Forum, 2023, 1089: 165-174.
[15] 崔昕茹, 霍雪萍, 周炳杰, 等. 我国煤矸石空间分布特征与分级分质利用路径[J]. 环境科学, 2025, 46(4): 1-14.
CUI X R, HUO X P, ZHOU B J, et al. Spatial distribution characteristics and graded and graded utilization paths of coal gangue in China[J]. Environmental Science, 2025, 46(4): 1-14 (in Chinese).
[16] TIRONI A, TREZZA M A, SCIAN A N, et al. Kaolinitic calcined clays: factors affecting its performance as pozzolans[J]. Construction and Building Materials, 2012, 28(1): 276-281. [17] TEKLAY A, YIN C G, ROSENDAHL L. Flash calcination of kaolinite rich clay and impact of process conditions on the quality of the calcines: a way to reduce CO₂ footprint from cement industry[J]. Applied Energy, 2016, 162: 1218-1224.
[18] SAN NICOLAS R, WANG T C, RUPASINGHE M. Effect of calcined clays from Victoria, Australia as cement substitution in ternary blended cement systems[J]. Case Studies in Construction Materials, 2024, 20: e02860.
[19] AVET F, SCRIVENER K. Investigation of the calcined kaolinite content on the hydration of limestone calcined clay cement (LC³)[J]. Cement and Concrete Research, 2018, 107: 124-135.