Hydration and Strength Evolution of Ternary-Blend High-Volume Fly Ash Concretes

Gunasekera, Chamila; Zhou, Zhiyuan; Sofi, Massoud; Law, David W.; Setunge, Sujeeva; Mendis, Priyan

doi:10.14359/51716815

Cited by 8 publications

(3 citation statements)

References 28 publications

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“…Fly Ash from coal fired power stations is a well established SCM. The substitution with fly ash generally fall in the range between 20-30% [6,7] and can be up to 80% in concretes containing high volumes of fly ash in the concrete [8][9][10]. It is also possible to use concentrated alkali activators with 100% replacement of fly ash, to produce geopolymer concrete [11-18] [Law, 2012[11-18] [Law, #1257.…”

Section: Introductionmentioning

confidence: 99%

Development of durable class F fly ash based geopolymer concretes

Law

Gunasekara

Patrisia

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

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The production of Portland Cement (PC) has been shown to be responsible for 5-8% of global CO2 emissions. This has led to class F fly ash based geopolymer concrete being developed as a substiture for PC concrete for to reduce these global CO2 emissions. However, research has shown that each fly ash has unique characteristics and requires a specific mix design for each fly ash. This is can occupy a significant amount of time. Furthermore, before the mix can be adopted for commercial application it requires the long-term durability to be established. This gap is one of the primary limitations delaying the adoption of geopolymer concrete. While each fly ash is unique, they do have common characteristics which can be utilized to optimise the mix design process. Geopolymers are also known to have good durability characteristics, in particular for acid and sulphate exposure. This paper reports the mix design optimisation process for six class F fly ashes from Australia, Sri Lanka and Indonesia. The strength properties and durability performance of the optimised mixes is reported including the compressive strength development, chloride and carbonation resistance together with performance when exposed to sulphate and acidic media for the Indonesian fly ash, including to a simulated peat soil designed to replicate the conditions experienced in Indonesia.

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Section: Introductionmentioning

confidence: 99%

Development of durable class F fly ash based geopolymer concretes

Law

Gunasekara

Patrisia

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

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“…The pozzolanic effect of FA could improve the durability and late age mechanical properties of cement-based materials [ 7 , 24 , 25 , 26 , 27 ]. However, the pozzolanic relativity of FA is quite low, so the replacement of cement with FA will reduce the early-age strength of cement-based materials [ 28 ]. Due to the morphological effect, the workability of cement-based materials could be improved [ 19 , 26 , 29 ], and the autogenous and drying shrinkage of cement-based materials could be restricted due to the micro-aggregate effect of FA [ 30 , 31 ].…”

Section: Introductionmentioning

confidence: 99%

“…Compared with normal FA concrete, i.e., concrete with a relatively low content of FA, HVFA concrete contains a lower content of cement. Hence its hydration process and performance development are different from that of normal FA concrete [ 28 , 37 , 40 ]. With the increase of FA content, the early age strength of concrete is lower, and longer time is required to reach its final strength [ 41 ].…”

Section: Introductionmentioning

confidence: 99%

The Relationship of Compressive Strength and Chemically Bound Water Content of High-Volume Fly Ash-Cement Mortar

Yao

Yang

et al. 2021

Materials

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Fly ash (FA) has been widely used in cement-based materials, but limited work has been conducted to establish the relationship between the compressive strength and hydration process of high-volume FA (HVFA)-cement-based material. In this study, the compressive strength and chemically bound water contents of FA-cement-based materials with different water-to-binder ratios (0.4, 0.5, and 0.6) and FA contents (0%, 30%, 40%, 50%, 60%, and 70%) were tested. Replacing more cement with FA reduced the compressive strength and of HVFA-cement-based materials. The compressive strength and chemically bound water content reduced by about 60–70% when 70% cement was replaced by FA. Water-to-binder ratio showed more significant influence on the chemically bonded water at later ages than that at early ages. Based on test results, the prediction equation of chemically bound water content was established, and its accuracy was verified. The error was less than 10%. The relationship between the compressive strength and chemically bound water content was also fitted. The compressive strength and chemically bound water content showed linear relationships for different water-to-binder ratios, hence the compressive strength of HVFA-cement mortar could be predicted with the chemically bound water content and water-to-binder ratios. The results of this study could be used for the prediction of the compressive strength development of HVFA-cement mortars, and is helpful to develop the mix design method of HVFA-cement-based materials.

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Physical, mechanical, and microstructural characteristics of fly ash replaced cement deep mixing columns

Yenginar,

Olgun

2024

Bull Eng Geol Environ

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The novel approach of the study is implementing the installation procedure of fly ash (FA) replaced cement deep mixing (DM) columns to field cases aiming at managing FA waste and reducing cement utilization. FA replaced cement DM columns (diameter of 30 cm and length of 80 cm) were installed on clayey soils using a laboratory type DM machine. The effect of installation parameters such as the binder dosage, FA replacement ratio, superplasticizer content, water/binder ratio, and the liquidity index (LI) of the soil on column performance was investigated. The design of experiments and optimization process were conducted using the Taguchi method, S/N and ANOVA analyses, and the desirability function method. Observations have shown that the mixing time required for a homogeneously mixed column depends on the LI of the soil and the volume ratio (VR) of the slurry. A key parameter (LI∙VR) is defined to decide the minimum number of the mixing process. The blade rotation number should be minimum of 252 rev/m to obtain a homogeneous soil-slurry mixture. The highest strength of the column was obtained when LI of fresh soilcrete (LImix) is 1.25∙LI. Optimum installation parameters were determined as binder dosage of 425 kg/m3, FA replacement ratio is 40%, superplasticizer content is 3%, water/binder ratio is 0.8, and LI of the untreated soil is 1. In the optimum design, the mixing efficiency of the soil-slurry mixture increased and the best column performance was obtained. In addition, cement utilization and binder cost decrease 40% and 33%, respectively, in FA-replaced cement DM columns. SEM images prove the increase in column performance due to the cementation products (CSH and CAH gels) formed in the microstructure of the column.

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Hydration and Strength Evolution of Ternary-Blend High-Volume Fly Ash Concretes

Cited by 8 publications

References 28 publications

Development of durable class F fly ash based geopolymer concretes

Development of durable class F fly ash based geopolymer concretes

The Relationship of Compressive Strength and Chemically Bound Water Content of High-Volume Fly Ash-Cement Mortar

Physical, mechanical, and microstructural characteristics of fly ash replaced cement deep mixing columns

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