Effect of fly ash on compressive strength degradation due to calcium leaching procedure

Lu, Cairong; Yang, Hu; Liu, Weibao; Mei, Guoxing; Wang, Heng; Ge, Xueliang

doi:10.1680/adcr.13.00012

Cited by 15 publications

(4 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is worth mentioning that the compressive strength diminution, which is due to the increase in the leaching time, becomes insignificant. These findings are consistent with those reported in several previous studies (Lu et al, 2014;Berra et al, 2013;Yang et al, 2012b).…”

Section: Compressive and Flexural Strengthssupporting

confidence: 94%

Effects of calcium leaching on the physical and mechanical properties of aerial lime-cement mortars

Bellifa

Boumechra

2019

JEDT

View full text Add to dashboard Cite

Purpose This paper aims to assess the effects of chemically accelerated leaching on the physical and mechanical properties of aerial lime–cement mortars (LCMs). Design/methodology/approach Two aerial LCMs, differencing mainly in their calcium hydroxide content, were degraded by the use of an ammonium nitrate solution as a leaching agent. The leaching effects were studied by evaluating the rate of change in physical (sorptivity and mass loss) and mechanical (flexural and compressive strength) characteristics of aerial LCMs. To quantify the evolution and kinetics of degradation, the leached depth was then characterized at different levels of degradation by means of a phenolphthalein solution. Findings The experimental results showed that the dissolution of binder decreases the mass, alkalinity and strength of aerial LCMs but increases their sorptivity. A linear relationship was derived by plotting the values of leached depth against the square root of immersion time in an aggressive solution. It was found that the leached depth followed diffusion-controlled kinetics. Originality/value It was found that the global loss of compressive strength of aerial LCMs because of complete dissolution of calcium hydroxide can reach up to 80 per cent.

show abstract

Section: Compressive and Flexural Strengthssupporting

confidence: 94%

Effects of calcium leaching on the physical and mechanical properties of aerial lime-cement mortars

Bellifa

Boumechra

2019

JEDT

View full text Add to dashboard Cite

show abstract

“…Roziere et al 6 demonstrated that adding 30% fly ash can reduce the content of calcium hydroxide in concrete and improve its corrosion resistance. Yang et al 7 and Lu et al 8 also proved that fly ash can improve the gel pore ratio and microstructure of the cement paste. Ye et al 9,10 of calcium corrosion of tunnel shotcrete through model tests.…”

Section: ■ Introductionmentioning

confidence: 96%

Reducing Calcium Dissolution in Tunnel Shotcrete: The Impact of Admixtures on Shotcrete Performance

Tong,

Tian,

et al. 2024

Langmuir

View full text Add to dashboard Cite

Groundwater infiltration into tunnels causes water to percolate through the fissure channels in the initial support shotcrete. This results in the dissolution and outflow of calcium hydroxide, a key product of cement hydration. This process significantly incurs the formation of crystallization blockages in the tunnel drainage systems. Optimizing the shotcrete mixing ratio is a feasible way to mitigate these blockages. Therefore, this study conducts calcium dissolution tests to investigate the impact of six admixtures, namely, antialkali agent, nanosilica, nanosilica carbonate, fly ash, sodium methyl silicate waterproofing agents, and silane waterproofing agents, on calcium dissolution resistance. Also, mechanical and microscopic tests are carried out to examine their impact on the strength and pore structure of the shotcrete. The objective of this study is to determine the optimal admixture for enhancing the calcium dissolution resistance of shotcrete. Results indicate that the antialkali agent significantly reduces the calcium leaching content of shotcrete. When the dosage is 14%, the calcium leaching amount is reduced by 68.4% in 28 days. Followed by nanosilica and silane waterproofing agents, with optimal dosages of 12 and 0.4%, respectively, the dissolution amount of calcium ions in shotcrete was reduced by 32.87 and 26.5%, respectively. Fly ash curing for 28 days can also reduce the calcium ion dissolution of shotcrete, while nanocalcium carbonate and sodium methyl silicate have little effect on the calcium dissolution of shotcrete. The antialkali agent with a strong calcium ion dissolution effect can improve the tensile strength of shotcrete under long-term curing conditions, which can be increased by 52%, but it compromises the growth of compressive strength. Nanosilica, fly ash, and silane waterproofing agents can improve both the compressive strength and tensile strength of shotcrete under long-term curing conditions. Specifically, at 28 days of curing, the compressive strength increased by 16.83, 28.8, and 20% and the tensile strength increased by 50.24, 60, and 64.5%. In addition, the microscopy results show that the antialkali agent, nanosilica, and silane waterproofing agents promote the hydration process of cement to form ettringite with a low and stable calcium−silicon ratio and reduce calcium hydroxide crystals. Nanosilica and silane waterproofing agents optimize the pore distribution in shotcrete by increasing beneficial pores, decreasing harmful pores, and reducing total porosity.

show abstract

“…The denser C-S-H gel decelerates the leaching process of calcium ions and slows the deterioration of strength of specimens with silica fume 16 . Also, the use of mineral additions such as silica fume is reported to result in a significant reduction of the transport propertied of the mixtures 17 . Furthermore, the calcium leaching decreases with increasing silica fume content 4 , which refine the pore structure through pozzolanic reaction, thus provide resistance to the leaching process from porosity generation 9 , 16 .…”

Section: Introductionmentioning

confidence: 99%

Calcium leaching behavior of cementitious materials in hydrochloric acid solution

Yang

Che

Leng

2018

Sci Rep

View full text Add to dashboard Cite

The calcium leaching behavior of cement paste and silica fume modified calcium hydroxide paste, exposed to hydrochloric acid solution, is reported in this paper. The kinetic of degradation was assessed by the changes of pH of hydrochloric acid solution with time. The changes of compressive strength of specimens in hydrochloric acid with time were tested. Hydration products of leached specimens were also analyzed by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric (TG), and atomic force microscope (AFM). Tests results show that there is a dynamic equilibrium in the supply and consumption of calcium hydroxide in hydrochloric acid solution, which govern the stability of hydration products such as calcium silicate hydrate (C-S-H). The decrease of compressive strength indicates that C-S-H are decomposed due to the lower concentration of calcium hydroxide in the pore solution than the equilibrium concentration of the hydration products. Furthermore, the hydration of unhydrated clinker delayed the decomposition of C-S-H in hydrochloric acid solution due to the increase of calcium hydroxide in pore solution of cementitious materials.

show abstract

Effect of fly ash on compressive strength degradation due to calcium leaching procedure

Cited by 15 publications

References 19 publications

Effects of calcium leaching on the physical and mechanical properties of aerial lime-cement mortars

Effects of calcium leaching on the physical and mechanical properties of aerial lime-cement mortars

Reducing Calcium Dissolution in Tunnel Shotcrete: The Impact of Admixtures on Shotcrete Performance

Calcium leaching behavior of cementitious materials in hydrochloric acid solution

Contact Info

Product

Resources

About