Degradation processes of reinforced concretes by combined sulfate–phosphate attack

Secco, Michele; Lampronti, Giulio I.; Schlegel, Moritz Caspar; Maritan, Lara; Zorzi, Federico

doi:10.1016/j.cemconres.2014.10.023

Cited by 20 publications

(5 citation statements)

References 34 publications

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“…Phosphates (H2PO4 -, HPO4 2or PO4 3-), are one of the main components in silage effluent discharged by agricultural practices with a resultant acidic condition (pH ≈ 3.5-5) [20], posing severe challenges for cementitious materials used in sewer networks [8,21,22]. According to related research [23], fertilizer production could produce a dilute mixture of phosphoric, sulfuric and even fluosilic acids with pH level as low as 1 to 2. Previous studies have shown that the exposure of OPC concretes to phosphoric acid (pH = 2, 3 or 4) or phosphate-rich acidic environments resulted in significant degradation [1,8,24].…”

Section: Introductionmentioning

confidence: 99%

Degradation resistance of different cementitious materials to phosphoric acid attack at early stage

Ren

Zhang

Walkley

et al. 2022

Cement and Concrete Research

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Section: Introductionmentioning

confidence: 99%

Degradation resistance of different cementitious materials to phosphoric acid attack at early stage

Ren

Zhang

Walkley

et al. 2022

Cement and Concrete Research

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“…e ardealite peak disappeared after the 1st dry-wet cycle. Ardealite is a monoclinic crystal system, and the sulfate in ardealite can be replaced [35]. Besides needle-like ettringite, more C-S-H gels could be observed in samples after dry-wet cycles (Figures 7(c) and 7(d)).…”

Section: Microstructural Characteristicsmentioning

confidence: 99%

“…Some C-S-H could also be observed in Figure 7(b). Ardealite (Ca(SO 4 ) (PO 3 (OH))• 4H 2 O) can be detected in samples S5 and S4, which easily formed in sulfate environment when SR content was high [35].…”

Section: Microstructural Characteristicsmentioning

confidence: 99%

Durability Analysis of Sludge Solidified with Soda Residue Subjected to Dry‐Wet and Freeze‐Thaw Cycles

Zhang

2021

Advances in Civil Engineering

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Soda residue (SR), ground-granulated blast-furnace slag (GGBS), and quicklime (QL) were employed for solidifying sewage sludge, which is a technique for sustainable development by transforming industrial solid waste and sludge into engineering fill material such as backfill material in mine or abandoned caverns. The durability of solidified sludge against dry-wet and freeze-thaw cycles was investigated by unconfined compressive strength (UCS), X-ray diffraction, scanning electron microscopy, and nuclear magnetic resonance tests. The results demonstrated that the SR-GGBS-QL solidified sludge had good dry-wet and freeze-thaw durability. In general, UCS increased at first, but then it decreased to some degree with the increase in dry-wet and freeze-thaw cycles. The cycle number for peak UCS depended on the durability test types and SR content. The UCS values after seven dry-wet cycles or ten freeze-thaw cycles were higher than the initial values before cycles. The main products detected in SR-GGBS-QL solidified sludge were ettringite, hydroaluminite, and calcium silicate hydrate (C-S-H). In addition, some pollutants such as copper, arsenic, and chromium were stabilized. The weakening effect on the microstructure of the solidified sludge occurred after dry-wet or freeze-thaw cycles. However, the hydration reaction continued with the increase of dry-wet and freeze-thaw cycles, leading to an increase in the amount of hydration products (especially C-S-H) and compact microstructure. These contributed to high UCS values and good dry-wet and freeze-thaw durability. The strength and failure strain of solidified sludge still met the requirement of filling materials after dry-wet or freeze-thaw cycles.

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“…Reinforced concrete (RC) is the most widely used construction material in the world. However, RC structures will inevitably generate different forms of cracks in their service life due to materials, design, construction load and temperature stress (Bernal Camacho et al 2014;Liang and Wang 2020;Secco et al 2015;Weerdt et al 2014). Cracks provide a preferential path for aggressive Clpenetrating into the concrete, which will dramatically accelerate the corrosion of reinforcement and lead to the deterioration of concrete construction (Li et al 2019(Li et al , 2021Shen et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Effect of Seawater and Various Parameters on Electro-deposition Repairing Cracks of Reinforced Concrete Exposed to Marine Environment

Feng

Jin

Zhu

et al. 2022

ACT

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Electro-deposition repairing concrete crack technique is of vital importance to prolong the service life of the concrete structure in the marine environment. In this paper, the repairing effect using seawater as an electrolyte was compared with ZnSO 4 solutions, and the mechanism of electro-deposition repairing concrete cracks under seawater environments was investigated. Besides, various parameters such as electrode materials, electrode distances and current density were studied in seawater. The experimental results indicated that electro-deposition repair using seawater is highly effective compared to using ZnSO 4 solutions. The Clremoval efficiency can reach to 16.25% with titanium mesh as the anode and seawater as the electrolyte. The main crystal mineral composition using seawater is brucite, calcite and aragonite, and the percentages of Mg(OH) 2 , Ca(OH) 2 and CaCO 3 are approximately 68%, 7% and 23%, respectively. Rather than Na + , Mg 2+ and Ca 2+ in seawater were the primary ions promoting the repair of concrete cracks. When the seawater and titanium mode was used, the reaction products were the densest and the repairing effect was the best. Furthermore, when the titanium electrode distance was 0 mm and the current density was 0.25 to 0.5 A/m 2 , the electro-deposition repairing effect was the best. This paper presents a new method for the research of electro-deposition repairing concrete cracks in the submerged zone of marine environment.

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Degradation processes of reinforced concretes by combined sulfate–phosphate attack

Cited by 20 publications

References 34 publications

Degradation resistance of different cementitious materials to phosphoric acid attack at early stage

Degradation resistance of different cementitious materials to phosphoric acid attack at early stage

Durability Analysis of Sludge Solidified with Soda Residue Subjected to Dry‐Wet and Freeze‐Thaw Cycles

Effect of Seawater and Various Parameters on Electro-deposition Repairing Cracks of Reinforced Concrete Exposed to Marine Environment

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