Ewa Kapeluszna

Bio: Ewa Kapeluszna is an academic researcher from AGH University of Science and Technology. The author has contributed to research in topics: Cement & Pozzolan. The author has an hindex of 5, co-authored 17 publications receiving 172 citations.

Incorporation of Al in C-A-S-H gels with various Ca/Si and Al/Si ratio: Microstructural and structural characteristics with DTA/TG, XRD, FTIR and TEM analysis

Abstract: Systems of different Ca/Si and Al/Si molar ratios were investigated. Incorporation of Al increases main basal spacing, amount of bounded water and decreases crystallinity of C-(A)-S-H (calcium (aluminium) silicate hydrate). Transmission electron microscope observations showed that aluminium results in formation of more compacted, foil-like microstructure. FTIR revealed the presence of rings within the structure of C-(A)-S-H. Low Ca/Si ratio promotes Al incorporation into C-(A)-S-H, while in case of high Ca/Si ratio aluminium is also incorporated into AFm. The results show, that Ca/Si ratio is of key significance deciding on Al incorporation into C-(A)-S-H in hydrating SCMs bearing blended systems.

Utilization of waste expanded perlite as new effective supplementary cementitious material

Abstract: Expanded perlite is a valuable lightweight material for building materials industry as well as for agriculture, horticulture etc. Unfortunately during both production as well as processing of expanded perlite, some fine grained waste perlite is being formed. Due to its extremely low bulk density waste expanded perlite is difficult to handle, utilize and causes dust formation. Paper presents method of utilization of waste expanded perlite as a valuable, high performance pozzolanic supplementary cementitious material. Waste expanded perlite was ground in ball mill in order to destroy cellular microstructure of waste expanded perlite. It resulted in significant increase in specific surface area of material. Results of strength tests showed, that addition of ground waste expanded perlite may result in strength gain up to 50% (for 35% addition in respect to cement mass). Due to its high activity ground waste expanded perlite can be used as both cement substitute as well as cement additive depending on desired properties of final material. Investigations showed, that ground waste expanded perlite is material of pozzolanic activity. Except strength test, pozzolanic activity was investigated by solubility test according to ASTM C379-65T. Direct measurements of calcium hydroxide content in hydrating alite pastes confirmed that ground expanded perlite reacts with calcium hydroxide what results in reduction of calcium hydroxide content in alite paste. Pozzolanic activity of ground waste expanded perlite was compared with commonly used commercial pozzolanas. Obtained results allow to classify ground waste expanded perlite as material of pozzolanic properties. It can be valuable supplementary cementitous material mainly for special applications due to its high pozzolanic activity and very bright, almost white colour. In addition to that, ground waste expanded perlite used as cement replacement allows to decrease carbon dioxide emission, since Portland cement manufacturing is connected with emission of considerable amount of carbon dioxide.

Cement-based composites with waste expanded perlite - Structure, mechanical properties and durability in chloride and sulphate environments

Abstract: Implementation of fine, dusty materials generated during the production of expanded perlite is a challenge from the waste disposal point of view. However, after proper treatment, it is possible to use them in the composite building materials manufacturing where they can play a role of so-called pozzolanic additive, strengthening setting and hardening process when mixed with cement. In this study waste expanded perlite – Portland cement composites were exposed to the action of sodium chloride, sodium sulphate and magnesium sulphate solution. The results show that the durability of cement composites with waste expanded perlite is significantly improved; the lifecycle of these materials would be markedly enhanced. Due to the pozzolanic reaction between the vitreous aluminosilicate component of perlite and calcium hydroxide released from cement clinker, the phase assemblage of hardened cement matrix is changed towards the partial replacement of calcium hydroxide by the C-S-H phase. The amount of calcium hydroxide is therefore markedly reduced, as well as the pore refinement and compact microstructure of products is observed. As a consequence, the compressive strength increases, the permeability of final material decreases. Therefore the durability of Portland cement - perlite mortars is significantly improved. The reference mortars with cement subjected to the sodium and magnesium sulphate started to expand after 200 and 100 days of curing respectively. They were destroyed after about a year, while the samples containing 20% of WEP exhibited no expansion after 5 years of storage in corrosive solutions.

The effect of highly reactive pozzolanic material on the early hydration of alite – C3A – gypsum synthetic cement systems

Abstract: Paper focuses on the mechanism of hydration of synthetic cements consist of alite, tricalcium aluminate and gypsum with variable amounts of highly reactive pozzolanic material – ground waste expanded perlite (WEP). Hydration was traced using conductometric studies of slurries together with calorimetric, XRD, SEM and thermal analysis of pastes. The presence of ground WEP causes faster renewal dissolution of the C3A phase due to faster consumption of sulphate ions. The results suggest an accelerated transformation of ettringite to monosulphate in the presence of WEP. The formation of a larger amount of C-S-H phase which has immobilisation properties to SO42− ions was found.

Comparison of the effect of ground waste expanded perlite and silica fume on the hydration of cements with various tricalcium aluminate content – Comprehensive analysis

Abstract: The influence of ground waste expanded perlite (WEP) and silica fume on the hydration of two cements containing 2% and 7% of C3A was investigated. The effect of additives was different depending on the C3A content, especially at the early stage of hydration. Aluminates hydration was strongly affected, which manifested in the alteration of the aluminate calorimetric peak related to the renewal hydration of C3A. In the presence of pozzolans, the amount of Ca(OH)2 was reduced and more C-S-H was formed. Therefore, the compressive strength increased and the porosity decreased. The correlation between the early compressive strength and the heat of hydration as a function of pozzolan content was linear only for cement with 7% of C3A. FTIR studies revealed the differences in the evolution of bands originating from WEP and silica fume during hydration. FTIR can possibly be used for the determination of pozzolanic reaction progress of the latter.

Recent progress in low-carbon binders

Abstract: The development of low-carbon binders has been recognized as a means of reducing the carbon footprint of the Portland cement industry, in response to growing global concerns over CO2 emissions from the construction sector. This paper reviews recent progress in the three most attractive low-carbon binders: alkali-activated, carbonate, and belite-ye'elimite-based binders. Alkali-activated binders/materials were reviewed at the past two ICCC congresses, so this paper focuses on some key developments of alkali-activated binders/materials since the last keynote paper was published in 2015. Recent progress on carbonate and belite-ye'elimite-based binders are also reviewed and discussed, as they are attracting more and more attention as essential alternative low-carbon cementitious materials. These classes of binders have a clear role to play in providing a sustainable future for global construction, as part of the available toolkit of cements.

Green concrete composite incorporating fly ash with high strength and fracture toughness

Abstract: Nowadays green buildings are a necessary component of securing sustainability, whereas concrete composites with the addition of siliceous fly ash (FA) can certainly be included in the sustainable and green concrete. Effective promotion of green concrete incorporating FA is required in order to minimize the environment threat due to FA waste disposal and reduce cement consumption. In this paper, effects of FA addition on the compressive strength f cm and fracture toughness of plain concrete are presented. Fracture toughness tests were carried out according to Mode I (tension at bending) following the RILEM Draft Recommendations. The critical values of stress intensity factors, K Ic S have been determined. To assess mechanics parameters compressive strength tests and fracture toughness tests were conducted and the results were evaluated comparing with reference concrete. In modified concretes, cement was replaced by FA by its weight. Three test groups were constituted with the replacement percentages as: 0% (FA-00), 20% (FA-20) and 30% (FA-30). During the tests, the effect of age of concretes modified with the additive of FA on analysed parameters was determined. The experiments were carried out after: 3, 7, 28, 90, 180 and 365 days of curing. Based on the obtained results it can be concluded that, it is possible to make green concrete containing FA with high compressive strength and fracture toughness. The properties of composites with the additive of FA depend on the age of the concrete during tests. 20% additive of FA guarantees high f cm and K Ic S in mature concretes. Moreover results of the K Ic S and the f cm are convergent qualitatively.

Feasibility of using fly ash-slag-based binder for mine backfilling and its associated leaching risks.

Abstract: As a binder to completely replace Portland cement for mine backfilling, the use of clinker-free cementitious materials combined with municipal solid waste incineration (MSWI) fly ash is proposed to achieve the targets of low-cost green backfilling, safe disposal and resource utilisation of bulk urban hazardous waste and metallurgical solid waste. This study balances the positive and negative effects of adding MSWI fly ash to the backfill by controlling its quantity in the binders, thus establishing an optimal concentration of 49 wt.% steel slag (SS), 21 wt.% blast furnace slag (BFS), 10 wt.% MSWI fly ash and 20 wt.% flue gas desulfurisation (FGD) gypsum. It is also reported that the filling performance of slurry (A2) satisfied strength requirements and is very suitable for long-distance transportation according to filling parameters. The leaching levels of the target elements (Cr, Ni, Zn, As, Cd, Sb, Pb, Hg and dioxins) for A2 matrix are lower than the required maximum concentration limits for the underground class Ⅲ water standard. Furthermore, the risk of leaching harmful constituents is mainly controlled by the pH of the environmental and the excellent buffering capacity of the matrix can reduce the potential leaching risk. The encapsulation, precipitation and adsorption of low-solubility double salts, such as hydrate calcium chloroaluminate (HCC) and ettringite, are the solidification/stabilisation (S/S) mechanism of series A on harmful substances. In addition, the high degree of polymerization(Ca/Si = 1.18 < 1.2, at 90d), the formation of long-chain C-S-H gels in binder A2-2, the dense pore structure lead to very stable growth in strength and control of leaching risks in subsequent periods.

Effect of relative humidity on the carbonation rate of portlandite, calcium silicate hydrates and ettringite

Abstract: The carbonation of portlandite, calcium silicate hydrate (C-S-H), and ettringite was investigated at 57% RH and 91% RH using X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, and the phenolphthalein spray test. The experiments show that the carbonation of portlandite, ettringite, and C-S-H with Ca/Si = 0.7 is significantly faster at 91% RH than at 57% RH. Little effect of RH is observed for C-S-H with higher Ca/Si. Portlandite and C-S-H with Ca/Si = 0.7 carbonate only partially at 57% RH; complete carbonation is observed if the relative humidity is increased to 91% RH. In contrast, the carbonation of C-S-H with Ca/Si = 1.2 and 1.5 is complete at both relative humidities. The carbonation rate of C-S-H decreases with decreasing Ca/Si ratio, both at 57% and 91%RH. Carbonation at 57% RH promotes the formation of vaterite and aragonite over calcite; the precipitation of amorphous calcium carbonate is observed for C-S-H with Ca/Si = 0.7.

Carbonation of steel slag and gypsum for building materials and associated reaction mechanisms

Abstract: The carbonation of steel slag to produce building material is a useful way to increase the utilization of steel slag and absorb carbon dioxide. In this study, gypsum, steel slag, and water were mixed, compaction-shaped, and carbonation-cured as a means of improving the strength of the steel slag. It was observed that gypsum promoted an increase in both the compressive strength and the CO2 uptake of steel slag. CO2 uptake was positively correlated with strength. Microanalysis indicated that the main hydration product were C-S-H phases and ettringite, while the main carbonation products were calcite and monocarbonate (C3A. CaCO3.11H2O). Gypsum is speculated to promote the rapid hydration of steel slag to form ettringite (C3A.3CaSO4.32H2O), which then reacts with CO2 to produce monocarbonate; thus, gypsum plays a catalytic role in this system. The results of this study therefore provide theoretical guidance for the preparation of steel slag–gypsum carbide building materials.