Topic
Efflorescence
About: Efflorescence is a research topic. Over the lifetime, 891 publications have been published within this topic receiving 10794 citations.
Papers published on a yearly basis
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Papers
TL;DR: In this paper, it was shown that salt damage due to crystallization pressure appears to be largely a function of solution supersaturation ratio and location of crystallization, which are constrained by solution composition, environmental conditions, substrate properties, and salt crystallization growth patterns.
Abstract: Micro- and macroscale experiments which document the dynamics of salt damage to porous stone have yielded data which expose weaknesses in earlier interpretations. Previously unexplained differences are found in crystal morphology, crystallization patterns, kinetics and substrate damage when comparing the growth of mirabilite (Na2SO4. 10H2O) and thenardite (Na2SO4) versus halite (NaCl). The crystallization pattern of sodium sulphate was strongly affected by relative humidity (RH), while a lesser RH effect was observed for sodium chloride. Macroscale experiments confirmed that mirabilite (crystallizing at RH > 50 per cent) and thenardite (crystallizing at RH < 50 per cent) tend to form subflorescence in highly localized areas under conditions of constant RH and temperature. This crystallization pattern was more damaging than that of halite, since halite tended to grow as efflorescence or by filling the smallest pores of the stone in a homogeneous fashion, a result which contradicts Wellman and Wilson's theoretical model of salt damage. Low RH promoted rapid evaporation of saline solutions and higher supersaturation levels, resulting in the greatest damage to the stone in the case of both sodium sulphate and sodium chloride crystallization. At any particular crystallization condition, sodium chloride tended to reach lower supersaturation levels (resulting in the crystallization of isometric crystals) and created negligible damage, while sodium sulphate reached higher supersaturation ratios (resulting in non-equilibrium crystal shapes), resulting in significant damage. ESEM showed no damage from sodium sulphate due to hydration. Instead, after water condensation on thenardite crystals, rapid dissolution followed by precipitation of mirabilite took place, resulting in stone damage by means of crystallization pressure generation.
It is concluded that salt damage due to crystallization pressure appears to be largely a function of solution supersaturation ratio and location of crystallization. These key factors are related to solution properties and evaporation rates, which are constrained by solution composition, environmental conditions, substrate properties, and salt crystallization growth patterns.
When combined with a critical review of salt damage literature, these experiments allow the development of a model which explains variations in damage related to combinations of different salts, substrates and environmental conditions.
664 citations
TL;DR: In this paper, the efflorescence of fly ash-based geopolymers is investigated. And the authors propose a relationship between alkali leaching from monosized fractured particles and the potential of efflorescence.
430 citations
TL;DR: In this paper, a pumice-type natural pozzolanic material from Taftan, Iran was used to reduce efflorescence in a geopolymer binder.
Abstract: This paper addresses methods to reduce efflorescence in a geopolymer binder based on a pumice-type natural pozzolanic material from Taftan, Iran. Geopolymer pastes samples are analyzed for compressive strength and efflorescence formation after curing at 95% humidity for 28 days. To reduce the extent of efflorescence, Al-rich mineral admixtures such as metakaolin, ground granulated blast-furnace slag, and three types of calcium aluminate cements are incorporated into the dry binder at a range of concentrations. Hydrothermal curing at elevated temperatures also shows a positive effect in efflorescence reduction. Calcium aluminate cements show the greatest effect in efflorescence reduction, which is attributed to their dissolution in alkaline media releasing high amounts of alumina into the aluminosilicate geopolymer gel. These results confirm that it is possible to develop a more reliable geopolymer binder with improved properties either by adding a suitable amount of active alumina to precursors such as natural pozzolan, or by manipulating the curing conditions to enhance alumina release from less-reactive precursor phases.
423 citations
TL;DR: In this article, the critical relative humidity of liquid-liquid phase separation (SRH), efflorescence (ERH), and deliquescence (DRH) was predicted using optical microscopy.
Abstract: . Individual particles that on a mass basis consist dominantly of the components ammonium sulfate, oxygenated organic material, and water are a common class of submicron particles found in today's atmosphere. Here we use (1) the organic-to-sulfate (org:sulf) mass ratio of the overall particle and (2) the oxygen-to-carbon (O:C) elemental ratio of the organic component as input variables in parameterisations that predict the critical relative humidity of several different types of particle phase transitions. Specifically these variables were used to predict the critical relative humidity of liquid-liquid phase separation (SRH), efflorescence (ERH), and deliquescence (DRH). Experiments were conducted by optical microscopy for 11 different oxygenated organic-ammonium sulfate systems covering the range 0.1
339 citations
TL;DR: In this paper, a test method of the efflorescence degree of fly ash based geopolymer was proposed and applied and the effects of the Si/Al ratio on products, microstructure, pore structures, compressive strength, water loss rate and efforescence of geopolymers were systematically investigated.
259 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 18 |
| 2024 | 53 |
| 2023 | 99 |
| 2022 | 123 |
| 2021 | 47 |
| 2020 | 62 |