The role of porosity in external sulphate attack

Ikumi, Tai; Cavalaro, Sérgio Henrique Pialarissi; Segura, Ignacio

doi:10.1016/j.cemconcomp.2018.12.016

Cited by 77 publications

(32 citation statements)

References 30 publications

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“…The pore size distribution curves presented in Figure 6 show that sulfate exposure refined the pore system, inducing a decline in 180 days mean diameter of 25.0% in OPC, 34.3% in OPC + 10GS, and 28.0% in OPC + 20GS. As noted by other researchers [ 43 , 44 ], decline is associated with a reduction in macropore volume and rises in the capillary (0.01 µm to 0.05 µm) and small capillary (0.002 µm< Φ < 0.01 μm) fractions. Such refinement was also consistent with the findings reported by Asensio et al [ 34 ], who also observed a shift in the curve to smaller diameters due to the precipitation of new compounds in the pore system and CDW masonry material pozzolanicity.…”

Section: Resultssupporting

confidence: 56%

“…As the data in Table 3 show, total porosity declined with exposure time by 18.7% in OPC, 20.9% in OPC + 10GS, and 24.7% in OPC + 20GS. The steeper decline in the samples bearing granite sludge was associated with their late-age pozzolanicity [27] and the precipitation of expansive compounds gypsum and ettringite in the pore system [44] that reduced permeability and retarded deterioration [45].…”

Section: Variation In Pore Structurementioning

confidence: 99%

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Sulfate Resistance in Cements Bearing Ornamental Granite Industry Sludge

et al. 2020

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This study explores the effect on sulfate resistance of the use of ornamental granite industry waste as a supplementary cementitious material (at replacement ratios of 10% and 20%) in cement manufacture. The present paucity of scientific knowledge of the behaviour of these new cements when exposed to an external source of sulfates justifies the need for, and the originality of, this research. After characterising the waste chemically and mineralogically, cement paste specimens were prepared in order to determine the durability of the newly designed eco-cements using Köch–Steinegger corrosion indices. The new hydration products, which might induce microstructural, mineralogical, or morphological decay in the specimens, were also analysed by comparing the samples before and after soaking in a sodium sulfate solution for different test periods. Respect to the results, the damage to pastes bearing 10% granite sludge (GS) is the same as observed in OPC, whilst the former exhibit a higher Köch-Steinegger corrosion rate (1.61) than both OPC and OPC+20GS. Soaking the pastes in sodium sulfate induces matrix densification due to ettringite formation and gypsum precipitation in the pores. Further to those results, at an optimal replacement ratio of 10%, these alternative, eco-friendlier materials can be used in the design and construction of non-structural cement-based (mortar or concrete) members exposed to an external source of sulfate.

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Section: Resultssupporting

confidence: 56%

Section: Variation In Pore Structurementioning

confidence: 99%

Sulfate Resistance in Cements Bearing Ornamental Granite Industry Sludge

et al. 2020

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“…The main reason that an appropriate amount of fibre can reduce the initial chloride penetration rate is that the fibre can effectively prevent the formation and development of shrinkage microcracks during the hardening process of concrete [ 36 , 37 , 38 ]. This is because the presence of microcracks significantly increases the chloride penetration rate into the concrete.…”

Section: Resultsmentioning

confidence: 99%

Chloride Diffusion Property of Hybrid Basalt–Polypropylene Fibre-Reinforced Concrete in a Chloride–Sulphate Composite Environment under Drying–Wetting Cycles

Yong

Niu

2021

Materials

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The effect of fibre reinforcement on the chloride diffusion property of concrete is controversial, and the coupling effect of sulphate erosion and drying–wetting cycles in marine environments has been neglected in previous studies. In this study, the chloride diffusion property of hybrid basalt–polypropylene fibre-reinforced concrete subjected to a combined chloride–sulphate solution under drying–wetting cycles was investigated. The effects of basalt fibre (BF), polypropylene fibre (PF), and hybrid BP–PF on the chloride diffusion property were analysed. The results indicate that the presence of sulphate inhibits the diffusion of chloride at the early stage of erosion. However, at the late stage of erosion, sulphate does not only accelerate the diffusion of chloride by causing cracking of the concrete matrix but also leads to a decrease in the alkalinity of the pore solution, which further increases the risk of corrosion of the reinforcing steel. An appropriate amount of fibre can improve the chloride attack resistance of concrete at the early stage. With the increase in erosion time, the fibre effectively prevents the formation and development of sulphate erosion microcracks, thus reducing the adverse effects of sulphate on the resistance of concrete to chloride attack. The effects of sulphate and fibre on the chloride diffusion property were also elucidated in terms of changes in corrosion products, theoretical porosity, and the fibre-matrix interface transition zone.

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“…Permeation of chloride to concrete was examined in [35]. The impact of sulfate ion activity on concretes was examined in [36][37][38][39][40]. Seawater is a more complex corrosive agent than the above-mentioned agents.…”

Section: Introductionmentioning

confidence: 99%

Old Dumped Fly Ash as a Sand Replacement in Cement Composites

Harasymiuk

Rudziński

2020

Buildings

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The use of industrial residues to replace natural resources for the production of building materials is economically and ecologically justified. Fly ash (FA) taken directly from electro-filters is commonly used as a cement replacement material. This is not the case, however, for old dumped fly ash (ODFA) that has been accumulating in on-site waste dumps for decades and currently has no practical use. It causes environmental degradation, which is not fully controlled by the governments of developed countries. The aim of the study was to assess the possibility of using ODFA as a partial replacement for sand in cement composites. ODFA replaced part of the sand mass (20% and 30%) in composites with a limited amount of cement (a cement-saving measure) and sand (saving non-renewable raw material resources). ODFA was activated by the addition of different proportions of hydrated lime, the purposes of which was to trigger a pozzolanic reaction in ODFA. The quantitative composition of the samples was chosen in such a way as to ensure the maximum durability and longevity of composites with a limited amount of cement. The 28-day samples were exposed to seawater attack for 120 days. After this period, the compressive strength of each sample series was determined. The results suggest the possibility of using ODFA with hydrated lime to lay town district road foundations and bike paths of 3.5 to 5 MPA compressive strength. What is more, these composites can be used in very aggressive environments.

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The role of porosity in external sulphate attack

Cited by 77 publications

References 30 publications

Sulfate Resistance in Cements Bearing Ornamental Granite Industry Sludge

Sulfate Resistance in Cements Bearing Ornamental Granite Industry Sludge

Chloride Diffusion Property of Hybrid Basalt–Polypropylene Fibre-Reinforced Concrete in a Chloride–Sulphate Composite Environment under Drying–Wetting Cycles

Old Dumped Fly Ash as a Sand Replacement in Cement Composites

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