Effect of Fly Ash Content on Drying Shrinkage and Compressive Strength of Alkali-Activated Materials

doi:10.16552/j.cnki.issn1001-1625.2024.1386

Abstract

Abstract: Alkali-activated materials are considered as potential alternatives to Portland cement. However, their high shrinkage rate remains a critical issue limiting widespread application. This study investigated the relationship between drying shrinkage and water loss rate of alkali-activated slag-fly ash paste. It examined the effect of fly ash content on compressive strength, reaction products, microstructure and hydration heat. The results show that with the increase of fly ash content, both drying shrinkage and water loss rate of alkali-activated slag increase. The fly ash content significantly affects the compressive strength of alkali-activated slag paste. In the early hydration stage (0~14 d), samples without fly ash exhibit higher compressive strength. However, in the later stage (14~28 d), samples with 20% (mass fraction) and 30% fly ash show a significant increase in strength. When the fly ash content is 20% and 30% and the Ca/Si ratio (molar ratio) is close to 1, it ensures strength development while reducing drying shrinkage and water loss rate.

Key words: cementitious material, alkali-activation, fly ash content, drying shrinkage, compressive strength

CLC Number:

TQ177

FU Zhenbo, YANG Xihao, ZHAO Yimeng, LIU Yunpeng, LI Shiji, LI Binghan, ZHAO Shuli, WANG Lei. Effect of Fly Ash Content on Drying Shrinkage and Compressive Strength of Alkali-Activated Materials[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2025, 44(5): 1717-1725.

References

[1] TRIPATHY S K, DASU J, MURTHY Y R, et al. Utilisation perspective on water quenched and air-cooled blast furnace slags[J]. Journal of Cleaner Production, 2020, 262: 121354.
[2] ZHU J W, CUI H Z, CUI L Z, et al. Mutual activation mechanism of cement-GGBS-steel slag ternary system excited by sodium sulfate[J]. Buildings, 2024, 14(3): 631.
[3] PACHECO-TORGAL F, CASTRO-GOMES J, JALALI S. Alkali-activated binders: a review part 1. historical background, terminology, reaction mechanisms and hydration products[J]. Construction and Building Materials, 2008, 22(7): 1305-1314.
[4] AYDıN1 S, BARADAN B. Mechanical and microstructural properties of heat cured alkali-activated slag mortars[J]. Materials & Design, 2012, 35: 374-383.
[5] JIA Z J, YANG Y Y, YANG L Y, et al. Hydration products, internal relative humidity and drying shrinkage of alkali activated slag mortar with expansion agents[J]. Construction and Building Materials, 2018, 158: 198-207.
[6] KHERADMAND M, ABDOLLAHNEJAD Z, PACHECO-TORGAL F. Shrinkage performance of fly ash alkali-activated cement based binder mortars[J]. KSCE Journal of Civil Engineering, 2018, 22(5): 1854-1864.
[7] YE H L, RADLIŃSKA A. Shrinkage mechanisms of alkali-activated slag[J]. Cement and Concrete Research, 2016, 88: 126-135.
[8] BALLEKERE KUMARAPPA D, PEETHAMPARAN S, NGAMI M. Autogenous shrinkage of alkali activated slag mortars: basic mechanisms and mitigation methods[J]. Cement and Concrete Research, 2018, 109: 1-9.
[9] 李爽, 刘和鑫, 杨永, 等. 碱激发矿渣/偏高岭土复合胶凝材料干燥收缩机理研究[J]. 材料导报, 2021, 35(4): 4088-4091.
LI S, LIU H X, YANG Y, et al. Mechanisms of drying shrinkage for alkali-activated slag/metakaolin composite materials[J]. Materials Reports, 2021, 35(4): 4088-4091 (in Chinese).
[10] 胡张莉. 碱激发矿渣粉煤灰水泥早期水化及收缩特性研究[D]. 长沙: 湖南大学, 2013: 48-72.
HU Z L. Study on early hydration and shrinkage characteristics of alkali-activated slag fly ash cement[D]. Changsha: Hunan University, 2013: 48-72 (in Chinese).
[11] FANG S, LAM E S S, LI B, et al. Effect of alkali contents, moduli and curing time on engineering properties of alkali activated slag[J]. Construction and Building Materials, 2020, 249: 118799.
[12] 龚建清, 董雅竹, 张浩, 等. 含玻璃砂的高性能碱激发矿渣砂浆性能研究[J]. 硅酸盐通报, 2022, 41(12): 4361-4368.
GONG J Q, DONG Y Z, ZHANG H, et al. Performance of glass sand-containing high-performance alkali-activated slag mortars[J]. Bulletin of the Chinese Ceramic Society, 2022, 41(12): 4361-4368 (in Chinese).
[13] 范小春, 杨东升, 张宇, 等. 外加剂对碱激发胶凝材料干燥收缩性能的影响[J]. 硅酸盐通报, 2024, 43(8): 2788-2796.
FAN X C, YANG D S, ZHANG Y, et al. Influences of additives on alkali-activated cementitious materials drying shrinkage performance[J]. Bulletin of the Chinese Ceramic Society, 2024, 43(8): 2788-2796 (in Chinese).
[14] 李军, 单继雄, 胡艳民, 等. 氧化钙膨胀剂减少碱激发矿渣混凝土自收缩的研究[J]. 混凝土, 2023(1): 78-81.
LI J, SHAN J X, HU Y M, et al. Study of reducing autogenous shrinkage of alkali-activated slag concrete with CaO expanding agent[J]. Concrete, 2023(1): 78-81 (in Chinese).
[15] LEE N K, JANG J G, LEE H K. Shrinkage characteristics of alkali-activated fly ash/slag paste and mortar at early ages[J]. Cement and Concrete Composites, 2014, 53: 239-248.
[16] GAO X, YU Q L, BROUWERS H J H. Assessing the porosity and shrinkage of alkali activated slag-fly ash composites designed applying a packing model[J]. Construction and Building Materials, 2016, 119: 175-184.
[17] YAO X, YANG T, ZHANG Z H. Compressive strength development and shrinkage of alkali-activated fly ash-slag blends associated with efflorescence[J]. Materials and Structures, 2016, 49(7): 2907-2918.
[18] KOVALCHUK, FERNÁNDEZ-JIMÉNEZ, PALOMO. Relationship between mechanical strength gains and initial ash chemistry[J]. Materiales de Construccion, 2008, 58(291): 35.
[19] FERNÁNDEZ-JIMÉNEZ A, PALOMO A. Composition and microstructure of alkali activated fly ash binder: effect of the activator[J]. Cement and Concrete Research, 2005, 35(10): 1984-1992.
[20] YE H L, CARTWRIGHT C, RAJABIPOUR F, et al. Understanding the drying shrinkage performance of alkali-activated slag mortars[J]. Cement and Concrete Composites, 2017, 76: 13-24.
[21] CHI M, HUANG R. Binding mechanism and properties of alkali-activated fly ash/slag mortars[J]. Construction and Building Materials, 2013, 40: 291-298.
[22] PROVIS J L, MYERS R J, WHITE C E, et al. X-ray microtomography shows pore structure and tortuosity in alkali-activated binders[J]. Cement and Concrete Research, 2012, 42(6): 855-864.
[23] 杨长辉, 刘先锋, 刘建. 碱矿渣水泥及混凝土化学外加剂的研究进展[J]. 混凝土, 2006(4): 17-18+28.
YANG C H, LIU X F, LIU J. The research progress of chemical admixture for alkali-activated slag cement and concrete[J]. Concrete, 2006(4): 17-18+28 (in Chinese).
[24] 姜保晓, 徐衍昌, 左俊卿, 等. 粉煤灰对不同胶凝体系干缩影响[J]. 粉煤灰综合利用, 2012, 26(2): 18-21.
JIANG B X, XU Y C, ZUO J Q, et al. Influence of fly ash on shrinkage performance of different cementitious system[J]. Fly Ash Comprehensive Utilization, 2012, 26(2): 18-21 (in Chinese).
[25] CHITHIRAPUTHIRAN S, NEITHALATH N. Isothermal reaction kinetics and temperature dependence of alkali activation of slag, fly ash and their blends[J]. Construction and Building Materials, 2013, 45: 233-242.
[26] SINGH B, RAHMAN M R, PASWAN R, et al. Effect of activator concentration on the strength, ITZ and drying shrinkage of fly ash/slag geopolymer concrete[J]. Construction and Building Materials, 2016, 118: 171-179.
[27] FANG G H, BAHRAMI H, ZHANG M Z. Mechanisms of autogenous shrinkage of alkali-activated fly ash-slag pastes cured at ambient temperature within 24 h[J]. Construction and Building Materials, 2018, 171: 377-387.
[28] 韩方晖, 刘娟红, 阎培渝. 温度对水泥-矿渣复合胶凝材料水化的影响[J]. 硅酸盐学报, 2016, 44(8): 1071-1080.
HAN F H, LIU J H, YAN P Y. Effect of temperature on hydration of composite binder containing slag[J]. Journal of the Chinese Ceramic Society, 2016, 44(8): 1071-1080 (in Chinese).
[29] LEE N K, LEE H K. Reactivity and reaction products of alkali-activated, fly ash/slag paste[J]. Construction and Building Materials, 2015, 81: 303-312.
[30] GRUSKOVNJAK A, LOTHENBACH B, HOLZER L, et al. Hydration of alkali-activated slag: comparison with ordinary Portland cement[J]. Advances in Cement Research, 2006, 18(3): 119-128.
[31] BEN HAHA M, LOTHENBACH B, LE SAOUT G, et al. Influence of slag chemistry on the hydration of alkali-activated blast-furnace slag: part I: effect of MgO[J]. Cement and Concrete Research, 2011, 41(9): 955-963.
[32] ISMAIL I, BERNAL S A, PROVIS J L, et al. Modification of phase evolution in alkali-activated blast furnace slag by the incorporation of fly ash[J]. Cement and Concrete Composites, 2014, 45: 125-135.
[33] 陈友治, 钟浩轩, 殷伟淞, 等. 钙硅比对水化硅酸钙结构、Zeta电势及减水剂吸附性能的影响分析[J]. 硅酸盐通报, 2020, 39(6): 1798-1804.
CHEN Y Z, ZHONG H X, YIN W S, et al. Effect of calcium-silicon ratio of calcium silicate hydrate on its structure, Zeta potential and adsorption capacity of superplasticizer[J]. Bulletin of the Chinese Ceramic Society, 2020, 39(6): 1798-1804 (in Chinese).
[34] CHAUBE R, KISHI T, MAEKAWA K. Modelling of concrete performance: hydration, microstructure and mass transport[M]. London: Routledge, 2005.
[35] MAEKAWA K, ISHIDA T. Modeling of structural performances under coupled environmental and weather actions[J]. Materials and Structures, 2002, 35(10): 591-602.