Chloride Binding Mechanism in Cement-Fly Ash-Slag-Metakaolin Quaternary Cementitious Materials

Abstract

Abstract: Based on the ternary cementitious materials composed of cement, fly ash and slag, the mineral admixture metakaolin was added to prepare quaternary cementitious materials. The relationship between hydration products of quaternary cementitious materials and chloride binding capacity was qualitatively analyzed by X-ray diffraction (XRD) and thermogravimetric analysis (TGA/DTG). The content of chloride by chemical binding and physical adsorption was quantitatively analyzed by TGA/DTG and Rietveld's external standard method. The results show that the addition of metakaolin increases the hydration rate of cement in early stage, and promotes the hydration of fly ash and slag powder, which makes the quaternary cementitious material hydrated to produce more AFm (4CaO·Al₂O₃·CaSO₄·13~19H₂O) and C-S-H gel. At the same time, the quaternary hydration system also increases the molar ratio of aluminum to calcium, which makes the monosulfoaluminate more inclined to the conversion of monocarboaluminate in the presence of carbonate. The results of isothermal adsorption of chloride ions show that the content of AFm phase is positively correlated with the binding capacity of chloride ions. The results of Rietveld's external standard method show that with the addition of metakaolin, the chemical chloride binding capacityof quaternary system is increased, but the physical adsorption capacity of quaternary system is reduced. Compared with the ternary system, the chemical chloride binding capacity increases by 94.16%, and the physical adsorption capacity decreases by 7.62%. TGA/DTG quantitative results show that Rietveld's method is feasible.

Key words: fly ash, slag, metakaolin, quaternary cementitious material, hydration product, chloride binding, quantitative analysis, XRD-Rietveld

CLC Number:

TU528

ZHANG Tao, GENG Jian, LIU Genjin, YANG Yudi, LIU Cijun. Chloride Binding Mechanism in Cement-Fly Ash-Slag-Metakaolin Quaternary Cementitious Materials[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2022, 41(6): 2063-2070.

References

[1] IPAVEC A, VUK T, GABROVŠEK R, et al. Chloride binding into hydrated blended cements: the influence of limestone and alkalinity[J]. Cement and Concrete Research, 2013, 48: 74-85.
[2] THOMAS M D A, HOOTON R D, SCOTT A, et al. The effect of supplementary cementitious materials on chloride binding in hardened cement paste[J]. Cement and Concrete Research, 2012, 42(1): 1-7.
[3] 莫利伟,耿健,柳俊哲,等.粉煤灰和矿粉双掺对水泥基材料固化氯离子能力的研究[J].硅酸盐通报,2013,32(12):2443-2448.
MO L W, GENG J, LIU J Z, et al. Study on fly ash and slag on binding of chloride ion into cement based materials[J]. Bulletin of the Chinese Ceramic Society, 2013, 32(12): 2443-2448 (in Chinese).
[4] DING W W, HE Y J, LU L N, et al. Influence of metakaolin on the conversion and compressive strength of quaternary phase paste[J]. Journal of the American Ceramic Society, 2020, 103(12): 7213-7225.
[5] HAN Y, OH S, WANG X Y, et al. Hydration-strength-workability-durability of binary, ternary, and quaternary composite pastes[J]. Materials, 2021, 15(1): 204.
[6] TANG L P, NILSSON L O. Chloride binding capacity and binding isotherms of OPC pastes and mortars[J]. Cement and Concrete Research, 1993, 23(2): 247-253.
[7] SCRIVENER K L, FüLLMANN T, GALLUCCI E, et al. Quantitative study of Portland cement hydration by X-ray diffraction/Rietveld analysis and independent methods[J]. Cement and Concrete Research, 2004, 34(9): 1541-1547.
[8] MATSCHEI T, LOTHENBACH B, GLASSER F P. The AFm phase in Portland cement[J]. Cement and Concrete Research, 2007, 37(2): 118-130.
[9] SHI H, YU Z Q, MA J, et al. Properties of Portland cement paste blended with coral sand powder[J]. Construction and Building Materials, 2019, 203: 662-669.
[10] VOGLIS N, KAKALI G, CHANIOTAKIS E, et al. Portland-limestone cements. Their properties and hydration compared to those of other composite cements[J]. Cement and Concrete Composites, 2005, 27(2): 191-196.
[11] WANG Y Y, SHUI Z H, GAO X, et al. Understanding the chloride binding and diffusion behaviors of marine concrete based on Portland limestone cement-alumina enriched pozzolans[J]. Construction and Building Materials, 2019, 198: 207-217.
[12] PANE I, HANSEN W. Investigation of blended cement hydration by isothermal calorimetry and thermal analysis[J]. Cement and Concrete Research, 2005, 35(6): 1155-1164.
[13] SURYAVANSHI A K, SWAMY R N. Stability of Friedel's salt in carbonated concrete structural elements[J]. Cement and Concrete Research, 1996, 26(5): 729-741.
[14] CHANG H L, FENG P, LYU K, et al. A novel method for assessing C-S-H chloride adsorption in cement pastes[J]. Construction and Building Materials, 2019, 225: 324-331.
[15] CSIZMADIA J, BALÁZS G, TAMÁS F D. Chloride ion binding capacity of aluminoferrites[J]. Cement and Concrete Research, 2001, 31(4): 577-588.
[16] SAIKIA N, KATO S, KOJIMA T. Thermogravimetric investigation on the chloride binding behaviour of MK-lime paste[J]. Thermochimica Acta, 2006, 444(1): 16-25.
[17] QIAO C Y, SURANENI P, NATHALENE WEI YING T, et al. Chloride binding of cement pastes with fly ash exposed to CaCl₂ solutions at 5 and 23 ℃[J]. Cement and Concrete Composites, 2019, 97: 43-53.
[18] BIRNIN-YAURI U A, GLASSER F P. Friedel's salt, Ca₂Al(OH)₆(Cl, OH)·2H₂O: its solid solutions and their role in chloride binding[J]. Cement and Concrete Research, 1998, 28(12): 1713-1723.