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We measured the reflectivity of Portlandite fine powder across a frequency range of 0.36-15 microns. The results are a combination of two datasets: one measured by a portable spectrophotometer (410-Solar, Surface Optics Corp.) and the other by an FTIR spectrometer (Jasco 6300) with an integrated sphere (PIKE). We extracted the data using SolarData and SpectraManager software, then merged it with KaleidaGraph software. The final merged data were exported to a .txt file.

We measured the reflectivity of Portlandite fine powder across a frequency range of 0.36-15 microns. The results are a combination of two datasets: one measured by a portable spectrophotometer (410-Solar, Surface Optics Corp.) and the other by an FTIR spectrometer (Jasco 6300) with an integrated sphere (PIKE). We extracted the data using SolarData and SpectraManager software, then merged it with KaleidaGraph software. The final merged data were exported to a .txt file.

Energy storage provides a greener path of efficient energy utilization. Recent trends of research suggest concrete as a potential thermal energy storage (TES) material. Its cheap commercial availability makes it one of the most deserving candidates. Cement paste is the key glue of concrete, hence performance of its major components in thermal conduction seeks thorough scientific study. Portlandite or calcium hydroxide is the second major component of cement paste, microscopically visible at a scale length of <10−4 m. Molecular dynamics (MD) simulation has been utilized to investigate the thermal transport mechanism of portlandite at an atomistic scale. The thermal conductivity of this component has been computed using three major force fields which are compared with the experimental outcome using modulated differential scanning calorimetry (MDSC). It has been observed that the simulation outcomes are in order with the experimental value but the results are sensitive to the choice of force fields. Excitation of molecules during thermal transport is predominantly governed by lower-frequency molecular vibration indicating the existence of Boson Peaks. This manuscript presents the full thermal conductivity tensor of portlandite along with the possible mechanism associated with thermal transport.

Although concrete and cement-based materials are the most engineered materials employed by mankind, their potential for use in daytime radiative cooling applications has yet to be fully explored. Due to its complex structure, which is composed of multiple phases and textural details, fine-tuning of concrete is impossible without first analyzing its most important ingredients. Here, the radiative cooling properties of Portlandite (Ca(OH)2) and Tobermorite (Ca5Si6O16(OH)2·4H2O) are studied due to their crucial relevance in cement and concrete science and technology. Our findings demonstrate that, in contrast to concrete (which is a strong infrared emitter but a poor sun reflector), both Portlandite and Tobermorite exhibit good radiative cooling capabilities. These results provide solid evidence that, with the correct optimization of composition and porosity, concrete can be transformed into a material suitable for daytime radiative cooling.

Current wastewater treatment technologies struggle to remove antibiotics from wastewaters, leading to contamination of surface and groundwater. Therefore, more effective and efficient processes for removing antibiotics from water are needed. The present study reports for the first time that three widely used antibiotics (amoxicillin, ceftriaxone, cefazoline) can be successfully removed from water under ambient conditions by using aqueous carbonation of portlandite. Breakthrough curves acquired from flow-through experiments and their respective removal isotherms were mainly used to determine quantitative equilibrium parameters. In this way, the removal of antibiotics using aqueous portlandite carbonation is very efficient for amoxicillin (9.5 mg/g), followed by cefazoline (4.3 mg/g) and ceftriaxone (2.7 mg/g). In a comparison perspective, nanomagnetite-interfacial Fenton reaction is more effective in removing amoxicillin (76.5 mg/g); however, the process is slower and chemically more complex. However, both investigated methods offer promising results at the laboratory scale and are technically feasible to be implemented in conventional and/or advanced wastewater treatment plants.

Pervious concrete (PCO) has many advantages and applications, such as water pooling reduction, noise attenuation, replenishment of groundwater reserves, etc. However, the use of pervious concrete is limited due to its low compressive strength and durability, especially as a result of portlandite leaching from concrete exposed to flowing water. The effects of active additives (nano SiO2 (NS) spent catalyst generated at the fluid catalytic cracking unit (FCCCw) and paper sludge waste burned at 700 °C (PSw)) along with particle size distribution of the coarse aggregate on the properties and durability of pervious concrete were determined in the research. Active additives used in the binder were found to reduce portlandite leaching from concrete exposed to flowing water to significantly increase the resistance of concrete to freezing and thawing cycles and to increase sound absorption, compressive strength and infiltration rate. In addition, industrial waste (FCCCw and PSw) used as active additives significantly reduced the use of clinker in concrete applied in the construction of water pervious systems. The coarse aggregate size distribution had the greatest effect on the density, ultrasound pulse velocity (UPV), porosity, compressive strength and infiltration rate of pervious concrete.

Pervious concrete (PCO) has many advantages and applications, such as water pooling reduction, noise attenuation, replenishment of groundwater reserves, etc. However, the use of pervious concrete is limited due to its low compressive strength and durability, especially as a result of portlandite leaching from concrete exposed to flowing water. The effects of active additives (nano SiO2 (NS) spent catalyst generated at the fluid catalytic cracking unit (FCCCw) and paper sludge waste burned at 700 °C (PSw)) along with particle size distribution of the coarse aggregate on the properties and durability of pervious concrete were determined in the research. Active additives used in the binder were found to reduce portlandite leaching from concrete exposed to flowing water to significantly increase the resistance of concrete to freezing and thawing cycles and to increase sound absorption, compressive strength and infiltration rate. In addition, industrial waste (FCCCw and PSw) used as active additives significantly reduced the use of clinker in concrete applied in the construction of water pervious systems. The coarse aggregate size distribution had the greatest effect on the density, ultrasound pulse velocity (UPV), porosity, compressive strength and infiltration rate of pervious concrete.

This paper aims to evaluate lightweight aggregates produced with hydrated cement paste powder (HCP) using both carbonation and normal curing. The comparative study was conducted to figure out the effects of the portlandite amount in HCP I and HCP III on the aggregates during carbonation curing. The addition of up to 10 wt% silica fume to HCP I was attempted to make full use of the considerable amount of portlandite to prepare artificial aggregates under normal curing. The mechanical properties, reaction products and microstructure were analysed and the results show that the optimal carbonation periods for HCP I- and HCP III-type aggregates are different due to different amount of portlandite. HCP I-type aggregates can gain 3.14 MPa after 7-day carbonation and contain 35.60 wt% calcium carbonates. The remaining 13.95 wt% portlandite shows the enormous potential in elevating the strength and CO2 capture capacity jointly via the optimized carbonation curing method. On the contrary, HCP III-type aggregates gained 2.97 MPa after 1-day carbonation and further carbonation decomposed C–S–H and lead to the formation of calcite and amorphous silica gel with significantly elevated specific surface area (from 10.69 m2/g to 42.96 m2/g). Additionally, the individual strength development of the prepared aggregates containing silica fume benefits from the sufficiently available portlandite due to the formation of secondary C–S–H, obtaining 2.39 MPa after 28-day normal curing.

The nucleation of the C-S-H gel is a complex process, key to controlling the hydration kinetics and microstructure development of cement. In this paper, a mechanism for the crystallization step during the C-S-H gel non-classical nucleation is proposed and explored by atomistic simulation methods. In the proposed mechanism portlandite precursor monolayers undergo a chemically induced transformation by condensation of silicate dimmers, forming C-S-H monolayers. We studied by DFT and nudged elastic band the structural transformation from bulk portlandite to a tobermorite-like calcium hydroxide polymorph, and the silicate condensation reaction at portlandite surface. Then, both processes are studied together, investigating the topochemical transformation from a portlandite monolayer to a C-S-H monolayer at room conditions using targeted molecular dynamics and umbrella sampling methods. Comparing the free energy of the process with thermodynamic data we conclude that the proposed mechanism is a potential path for C-S-H formation.

Pervious concrete (PCO) has many advantages and applications, such as water pooling reduction, noise attenuation, replenishment of groundwater reserves, etc. However, the use of pervious concrete is limited due to its low compressive strength and durability, especially as a result of portlandite leaching from concrete exposed to flowing water. The effects of active additives (nano SiO2 (NS) spent catalyst generated at the fluid catalytic cracking unit (FCCCw) and paper sludge waste burned at 700 °C (PSw)) along with particle size distribution of the coarse aggregate on the properties and durability of pervious concrete were determined in the research. Active additives used in the binder were found to reduce portlandite leaching from concrete exposed to flowing water to significantly increase the resistance of concrete to freezing and thawing cycles and to increase sound absorption, compressive strength and infiltration rate. In addition, industrial waste (FCCCw and PSw) used as active additives significantly reduced the use of clinker in concrete applied in the construction of water pervious systems. The coarse aggregate size distribution had the greatest effect on the density, ultrasound pulse velocity (UPV), porosity, compressive strength and infiltration rate of pervious concrete.

In this study, it is investigated the effect of Ca ion on dissolution and reaction products in alkaline environment using Pyrex glass showing ASR expansion and blast furnace slag fine aggregate suppressing ASR. It is reported that Ca plays a role in the dissolution and polymerization of silica, and is therefore an important factor in ASR. For each sample, calculation of dissolution rate and analysis of solid phase product by 29Si MAS NMR and XRD/Rietveld analysis, and liquid phase analysis by ICP-AES were performed. As a result, it was confirmed that addition of Ca has an influence on dissolution behavior of PG and BFS. In the reaction of PG, addition of Ca promotes the polymerization reaction of silica and increases the amount of N-S-H which has expandable and contributes to deterioration mechanism. On the other hand, in BFS, the dissolved silica did not polymerize and N-S-H did not form. It was suggested that the difference in ASR reactivity between PG and BFS is due to the difference in the reaction behavior.

The oxygen-isotope fractionations between brucite and water, portlandite and water, and brucite and portlandite have been calculated over the temperature range of 0 to 450 °C using quantum-chemical methods and several basis sets and functionals. The calculations also employ embedded clusters that are chosen using the Pauling-bond-strength-conserving termination method that maintains a neutral cluster with fractional charges assigned to terminal atoms. These calculations improve upon the previous semiempirical methods for predicting mineral-mineral fractionations. These semiempirical methods fail to accurately predict the relative enrichment and depletion of oxygen isotopes for the brucite-portlandite pair. The quantum calculations presented here also fail to predict at the absolute values for enrichment of oxygen isotopes between minerals and water, and a simple correction must be employed to achieve agreement with experiments if water is in the reaction. No such correction is needed to predict fractionation between minerals. The trends derived from the calculations are robust to changes in basis sets and functionals.

The oxygen-isotope fractionations between brucite and water, portlandite and water, and brucite and portlandite have been calculated over the temperature range of 0 to 450 °C using quantum-chemical methods and several basis sets and functionals. The calculations also employ embedded clusters that are chosen using the Pauling-bond-strength-conserving termination method that maintains a neutral cluster with fractional charges assigned to terminal atoms. These calculations improve upon the previous semiempirical methods for predicting mineral-mineral fractionations. These semiempirical methods fail to accurately predict the relative enrichment and depletion of oxygen isotopes for the brucite-portlandite pair. The quantum calculations presented here also fail to predict at the absolute values for enrichment of oxygen isotopes between minerals and water, and a simple correction must be employed to achieve agreement with experiments if water is in the reaction. No such correction is needed to predict fractionation between minerals. The trends derived from the calculations are robust to changes in basis sets and functionals.

Cementitious materials, used in a nuclear waste repository in the form of concrete or grout to ensure mechanical stability and sealing of disposal tunnels, constitute an important containment barrier for radionuclides in the event of water intrusion into a disposal site. The immobilization potential of hardened cement paste (HCP) as well as of calcium silicate hydrate (C-S-H), as main component of HCP, towards radionuclides such as Cm(III) or U(VI) has been demonstrated in a number of studies, e.g. [1-3]. To evaluate the retention potential of cementitious materials towards radionuclides at saline conditions, U(VI) and Cm(III) doped C-S-H phases were exposed to background electrolytes with salinities comparable to those reported for pore waters of North German clay formations, which are considered as potential host rocks. U(VI) and Cm(III) doped C-S-H phases with calcium-to-silicon (C/S) ratios ranging from 2.0 to 1.0, representing a portlandite saturated C-S-H system as well as chemically degraded cement paste, were synthesized directly in presence of either U(VI) or Cm(III). These phases were characterized by time-resolved laser-induced luminescence spectroscopy (TRLFS), infrared (IR) spectroscopy, powder X-ray diffraction (XRD), and scanning electron microscopy (SEM). Batch leaching experiments were performed for U(VI) doped CSH phases applying 2.5 M NaCl, 2.5 M NaCl/0.02 M Na2SO4, 2.5 M NaCl/0.02 M NaHCO3 or 0.02 M NaHCO3 and for Cm(III) doped CSH phases applying 2.5 M NaCl/0.02 M NaHCO3 or 0.02 M NaHCO3. The time-dependent release of Ca, Si, U or Cm from CSH phases into brines was followed up to 60 days. Leaching induced changes of the C-S-H structure and of the U(VI) or Cm(III) coordination environment were studied mainly with XRD and TRLFS or IR spectroscopy, respectively. Generally, the high immobilization potential of C-S-H gel towards U(VI) and Cm(III), reported in the literature, was verified. In the presence of saline solutions, the C-S-H phases showed d

Cementitious materials, used in a nuclear waste repository in the form of concrete or grout to ensure mechanical stability and sealing of disposal tunnels, constitute an important containment barrier for radionuclides in the event of water intrusion into a disposal site. The immobilization potential of hardened cement paste (HCP) as well as of calcium silicate hydrate (C-S-H), as main component of HCP, towards radionuclides such as Cm(III) or U(VI) has been demonstrated in a number of studies, e.g. [1-3]. To evaluate the retention potential of cementitious materials towards radionuclides at saline conditions, U(VI) and Cm(III) doped C-S-H phases were exposed to background electrolytes with salinities comparable to those reported for pore waters of North German clay formations, which are considered as potential host rocks. U(VI) and Cm(III) doped C-S-H phases with calcium-to-silicon (C/S) ratios ranging from 2.0 to 1.0, representing a portlandite saturated C-S-H system as well as chemically degraded cement paste, were synthesized directly in presence of either U(VI) or Cm(III). These phases were characterized by time-resolved laser-induced luminescence spectroscopy (TRLFS), infrared (IR) spectroscopy, powder X-ray diffraction (XRD), and scanning electron microscopy (SEM). Batch leaching experiments were performed for U(VI) doped CSH phases applying 2.5 M NaCl, 2.5 M NaCl/0.02 M Na2SO4, 2.5 M NaCl/0.02 M NaHCO3 or 0.02 M NaHCO3 and for Cm(III) doped CSH phases applying 2.5 M NaCl/0.02 M NaHCO3 or 0.02 M NaHCO3. The time-dependent release of Ca, Si, U or Cm from CSH phases into brines was followed up to 60 days. Leaching induced changes of the C-S-H structure and of the U(VI) or Cm(III) coordination environment were studied mainly with XRD and TRLFS or IR spectroscopy, respectively. Generally, the high immobilization potential of C-S-H gel towards U(VI) and Cm(III), reported in the literature, was verified. In the presence of saline solutions, the C-S-H phases showed d

We studied the Cm(III) retention by calcium silicate hydrate (C-S-H), portlandite (Ca(OH)2) and their alteration products calcite, vaterite, and aragonite in high ionic strength carbonate-containing solutions representing specific formation waters. For this, we synthesized C-S-H gels with calcium to silicon (C/S) ratios of 1.0 and 2.0 in the absence and presence of Cm(III), resulting in Cm(III)-free and Cm(III) doped C-S-H gel, respectively. For phase identification purposes we applied X-ray diffraction (XRD) while for the identification of the Cm(III)/C-S-H binding mode we applied site-selective time-resolved laser-induced luminescence spectroscopy (TRLFS). The stability of Cm(III) doped phases under repository-relevant conditions was evaluated by studying the time-dependent release of Cm(III) from the Cm(III) doped C-S-H gel into leaching solutions containing 0.02 M NaHCO3 or 2.5 M NaCl/0.02 M NaHCO3 over 60 d. Speciation changes of Cm(III) due to leaching were followed with TRLFS while C-S-H structure alterations and secondary phase formation were monitored with XRD. From the results it could be concluded that Cm(III) is not mobilized by aqueous carbonate but either remains incorporated in the C-S-H structure and portlandite or becomes partially re-immobilized into secondary CaCO3 phases. The presence of NaCl led to an accelerated conversion of metastable secondary CaCO3 phases into calcite.

The stability of calcium silicate hydrate (C-S-H) gel doped with uranium to form calcium uranium silicate hydrate (C-U-S-H) gel was investigated in 2.5 M NaCl, 2.5 M NaCl/0.02 M Na2SO4, 2.5 M NaCl/0.02 M NaHCO3 or 0.02 M NaHCO3 solutions relevant to the geological disposal of radioactive waste. The C-U-S-H gel samples were synthesized by direct U(VI) incorporation and characterized with time-resolved laser-induced luminescence spectroscopy (TRLFS), infrared (IR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Time-dependent pH changes as well as the Ca, Si and U release from C-U-S-H gels into the brines, determined by inductively coupled plasma mass spectrometry (ICP-MS), were monitored for three calcium-to-silicon (C/S) ratios (0.99, 1.55 and 2.02) over 32 d. Subsequently, changes of the U(VI) speciation and C-S-H mineralogy caused by leaching were investigated with TRLFS, IR spectroscopy and XRD. Results indicated that composition and pH value of the leaching solution, the presence of portlandite as well as formation and solubility of calcite as secondary phase determine the U(VI) retention by C-S-H gel under high saline and alkaline conditions. At high ionic strengths, the Ca release from C-S-H and secondary phases like calcite is increased. Under hyperalkaline conditions only small amounts of U(VI) were released during leaching. A decrease of the pH due to the additional presence of carbonate was linked with an increased U(VI) release from C-S-H gel leading to the formation of aqueous calcium uranyl carbonate in the supernatant solution.

The stability of calcium silicate hydrate (C-S-H) gel doped with uranium to form calcium uranium silicate hydrate (C-U-S-H) gel was investigated in 2.5 M NaCl, 2.5 M NaCl/0.02 M Na2SO4, 2.5 M NaCl/0.02 M NaHCO3 or 0.02 M NaHCO3 solutions relevant to the geological disposal of radioactive waste. The C-U-S-H gel samples were synthesized by direct U(VI) incorporation and characterized with time-resolved laser-induced luminescence spectroscopy (TRLFS), infrared (IR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Time-dependent pH changes as well as the Ca, Si and U release from C-U-S-H gels into the brines, determined by inductively coupled plasma mass spectrometry (ICP-MS), were monitored for three calcium-to-silicon (C/S) ratios (0.99, 1.55 and 2.02) over 32 d. Subsequently, changes of the U(VI) speciation and C-S-H mineralogy caused by leaching were investigated with TRLFS, IR spectroscopy and XRD. Results indicated that composition and pH value of the leaching solution, the presence of portlandite as well as formation and solubility of calcite as secondary phase determine the U(VI) retention by C-S-H gel under high saline and alkaline conditions. At high ionic strengths, the Ca release from C-S-H and secondary phases like calcite is increased. Under hyperalkaline conditions only small amounts of U(VI) were released during leaching. A decrease of the pH due to the additional presence of carbonate was linked with an increased U(VI) release from C-S-H gel leading to the formation of aqueous calcium uranyl carbonate in the supernatant solution.

In this study, it is investigated the effect of Ca ion on dissolution and reaction products in alkaline environment using Pyrex glass showing ASR expansion and blast furnace slag fine aggregate suppressing ASR. It is reported that Ca plays a role in the dissolution and polymerization of silica, and is therefore an important factor in ASR. For each sample, calculation of dissolution rate and analysis of solid phase product by 29Si MAS NMR and XRD/Rietveld analysis, and liquid phase analysis by ICP-AES were performed. As a result, it was confirmed that addition of Ca has an influence on dissolution behavior of PG and BFS. In the reaction of PG, addition of Ca promotes the polymerization reaction of silica and increases the amount of N-S-H which has expandable and contributes to deterioration mechanism. On the other hand, in BFS, the dissolved silica did not polymerize and N-S-H did not form. It was suggested that the difference in ASR reactivity between PG and BFS is due to the difference in the reaction behavior.

The stability of U(VI) doped calcium silicate hydrate (CSH) phases was evaluated in claystone formation waters that possess high ionic strengths and carbonate contents. Such phases were synthesized by direct U(VI) incorporation and characterized with time-resolved laser-induced fluorescence spectroscopy (TRLFS), infrared (IR) spectroscopy, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The time-dependent release of Ca, Si and U from U(VI) doped CSH phases into brines that contained 2.5 M NaCl, 2.5 M NaCl/0.02 M Na2SO4, 2.5 M NaCl/0.02 M NaHCO3 or 0.02 M NaHCO3 was monitored for three calcium-to-silicon (C/S) ratios over 32 days. Subsequently, changes of the U(VI) speciation and CSH phase mineralogy caused by leaching were investigated with TRLFS, IR spectroscopy and XRD. Results indicated that composition and pH of the leaching solution as well as presence and solubility of secondary phases such as portlandite and calcite determine the U(VI) retention by CSH phases under high saline and alkaline conditions. At high ionic strengths, the Ca release from CSH and secondary phases like calcite is increased. Under hyperalkaline conditions only small amounts of U(VI) were release during leaching. A decrease of the pH due to the additional presence of carbonate was linked with an increased U(VI) release from CSH phases caused by the occurrence of a calcium uranyl carbonate in the supernatant solution.

The transformation of industrial wastes into useful products attracts more researches to work upon for sustainable of natural resources. In this paper, industrial wastes such as treated textile effluent and fly ash were used in the preparation of plain cement concrete with the intention of reducing the environmental pollution caused by these materials. The partially treated textile effluent was used as mixing water and fly ash was used as 30% partial replacement by weight of cement in concrete. The textile effluents were collected after anaerobic treatment and tertiary treatment from textile industry. Class F Fly ash was collected from Mettur thermal power plant. The physical and chemical properties of treated textile effluent were studied. The control concrete was prepared with potable water available in the laboratory. Experimental test was performed for compressive strength of concrete at 28 days. The powdered concrete samples were examined through infrared spectroscopy, X-ray diffraction and scanning electron microscopy to study the microstructure of concrete. The compressive strength test results revealed that anaerobic effluent water (AAE) concrete accomplished higher compressive strength than control concrete. This was also in affirmation with microscopic analysis in which the formations of hydration products were well established when compared to control concrete.

Plane and crossed polarization are the two standard light modes in polarized light microscopy that are widely used to characterize crystalline and amorphous phases in cement-based materials. However, the use of the crossed polarized light mode has been found to be restrictive for studying birefringent phases quantitatively due to the extinction phenomenon that arises depending on the crystal orientation. This paper introduces circular polarization microscopy as an alternative technique to overcome the extinction problem during the examination of cementitious materials’ microstructure with optical microscopy. In order to evaluate the feasibility of this technique, selected optical and micromorphological features of portlandite clusters were investigated in cement paste. Image analysis results showed that compared to the conventional crossed polarization technique, circular polarization offers significant advantages when portlandite quantification is of interest, and it stands out as a promising low-cost alternative to backscattered electron microscopy., Structural Engineering, Civil Engineering and Geosciences

Plane and crossed polarization are the two standard light modes in polarized light microscopy that are widely used to characterize crystalline and amorphous phases in cement-based materials. However, the use of the crossed polarized light mode has been found to be restrictive for studying birefringent phases quantitatively due to the extinction phenomenon that arises depending on the crystal orientation. This paper introduces circular polarization microscopy as an alternative technique to overcome the extinction problem during the examination of cementitious materials’ microstructure with optical microscopy. In order to evaluate the feasibility of this technique, selected optical and micromorphological features of portlandite clusters were investigated in cement paste. Image analysis results showed that compared to the conventional crossed polarization technique, circular polarization offers significant advantages when portlandite quantification is of interest, and it stands out as a promising low-cost alternative to backscattered electron microscopy., Structural Engineering, Civil Engineering and Geosciences

Within the framework of the GTS-LCS project (Grimsel Test Site – Long-Term Cement Studies), an in-situ experiment lasting about 5 years was started in 2009 to study water-cement-rock interactions in fractured granite. A solid cement source (OPC) was installed in a borehole intersecting a water conducting fracture. Two other boreholes at about 0.56 m (observation) and 1.12 m (extraction) from the emplacement borehole were used to monitor the evolution of water composition in the fracture. Prior to the experiment, a tracer test was performed to characterize the initial flow and transport properties of the rock around the experimental boreholes. The flow and reactive transport calculations have been performed using the Retraso-CodeBright code. Solute transport is assumed to be controlled by diffusion in the cement and by advection-dispersion in the rock fracture. Initially, the flow model calculated from the results of the pre-emplacement tracer test, assuming a homogeneous fracture, was used to model reactive transport after emplacement of the cement. Since the small grid size from the flow model led to excessive computational times, the domain was divided into (a) a 1D radial model for the emplacement borehole and a small volume of rock around it, and (b) a 2D model for the rest of the domain. The results from (a) were used as input for (b). The model results show dissolution of portlandite and C-S-H in a thin (mm) external layer of the cement (emplacement borehole). In the rock fracture there is dissolution of the primary silicates (except phlogopite) and precipitation of C-S-H, C-A-S-H and calcite. Fracture porosity is reduced in a belt around the 3 boreholes, converging at the extraction borehole (due to the magnitude of the extraction flow rate). The decrease in porosity, due mainly to the precipitation of calcite, is stronger right next to the extraction borehole, due to the more favorable mixing conditions between Grimsel groundwater and cement porewater. The c, Preprint

TiN thin films prepared by magnetron sputtering have been evaluated as corrosion protective coatings for potential applications in concrete reinforcing steel. The interface between the cement paste and the TiN at several curing temperatures has been investigated by means of X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. Potentiodynamic polarization scans in a chloride buffer have been applied to establish the corrosion resistance modification of the nitride coatings after cement paste curing and setting. The results show that the augmented portlandite formation at the cement-TiN interface exhibits a clearly preferred orientation with (0 0 1) plane parallel to the interface. Nanosized C-S-H crystals are detected on the TiN coating, arranged in clusters. The local increase in the w/c ratio occurring at the interface promotes, along with high temperature exposition, the formation of micrometric ettringite dominantly at the interfacial zone. Electrochemical measurements reveal that TiN coatings show a superior corrosion behavior after cement paste setting.

Les objectifs de cette thèse sont de mieux comprendre le phénomène d’autocicatrisation naturelle et d’initier une démarche en vue de proposer des approches technologiques pratiques, fiables et peu couteuses qui permettront d’optimiser et de favoriser le potentiel d’autocicatrisation des bétons et des matériaux cimentaires en général. Les approches proposées consistent à introduire, dans les formulations des matériaux cimentaires, des réactifs internes latents qui permettront d’augmenter le potentiel d’autocicatrisation par différents mécanismes. Trois types de réactifs sont étudiés; des ajouts cimentaires riches en chaux libre, des ajouts granulés riches en ciment anhydre et/ou en chaux libre et des micro-granulats de verre riches en silice amorphe. L’ajout des ajouts cimentaire et des granulés visent à augmenter le potentiel d’autocicatrisation par carbonatation. L’ajout des micro-granulats de verre a pour objectif de créer, dans les fissures un gel silico-calcaire alcalin expansif. Il en ressort que l’augmentation de la teneur en portlandite de la matrice en ajoutant de réactifs riches en chaux libre augmente considérablement le potentiel d’autocicatrisation de fissures larges (>200 µm). L’ajout de granulés faiblement hydratés à base de ciment ou de ciment avec agent expansif à base de chaux libre confère aux mortiers une capacité de cicatrisation accrue. La formation de gel expansif dans les fissures suite à l’activation de la réaction alcali-silice des micro-granulats de verre ne confère pas à la matrice cimentaire un fort potentiel d’autocicatrisation entre 0 et 12 mois.

Mineralogical analysis on pastes of Spanish Portland cement Type I, blended with nanosilica was carried out by conventional and high-resolution thermogravimetric analysis (TG-HRTG) and X-ray diffraction (XRD) in order to determine the quantity of the different mineralogical phases obtained during the hydration process. Simultaneously, mortars with the same materials and replacement ratio were made in order to assess their compressive strength for up to 28 days of curing time. In this paper, the rate and quantity of each one of the main constituent phases of the cement during its hydration process (CSH, portlandite, stratlingite, etc.) were determined. A correlation between the quantity of CSH and the development of compressive strength was established. Additionally, the pozzolanic activity of nanosilica was evaluated by quantifying the fixation of calcium hydroxide and its impact on the development of the compressive strength. © 2012 Elsevier Ltd. All rights reserved.

Mineralogical analysis on pastes of Spanish Portland cement Type I, blended with nanosilica was carried out by conventional and high-resolution thermogravimetric analysis (TG-HRTG) and X-ray diffraction (XRD) in order to determine the quantity of the different mineralogical phases obtained during the hydration process. Simultaneously, mortars with the same materials and replacement ratio were made in order to assess their compressive strength for up to 28 days of curing time. In this paper, the rate and quantity of each one of the main constituent phases of the cement during its hydration process (CSH, portlandite, stratlingite, etc.) were determined. A correlation between the quantity of CSH and the development of compressive strength was established. Additionally, the pozzolanic activity of nanosilica was evaluated by quantifying the fixation of calcium hydroxide and its impact on the development of the compressive strength. © 2012 Elsevier Ltd. All rights reserved.

The hydration process of the cements induces the formation of different kinds of hydration products. The main products of hydration are C–S–H gel and portlandite [Ca(OH)2]. The C–S–H gel is an amorphous compound that is discomposed progressivity with the temperature until approximately 1,000 °C, while the portlandite is discomposed between 450 and 550 °C. Also, calcium carbonate can be formed as a consequence of the portlandite carbonation. All of these processes can be analysed and quantified by simultaneous differential thermal analysis and thermogravimetric analysis. And by X-ray diffraction it is possible to identify the crystalline phases. Some authors have corroborated that the portlandite can be rehydrated, after dehydration processes due to thermal exposition of the cement paste. But all of these experiments have been made with young cement pastes or at temperatures lower than 650 °C. In this work the behaviour of young and mature cement pastes have been studied in relation with the portlandite decomposition and the possibility of the rehydration of it in water presence. We found that young pastes and old pastes, stored at laboratory conditions, and later burned, show a certain grade of rehydration, specially the pastes burned at 650 °C (with ≈80% of reformation of portlandite) with respect to the pastes burned at 1,000 °C (between 20 and 40%). It is corroborate that the rehydration process is directly related to the formation of CaO during the burning. Also, a formation of unstable portlandite is detected in young pastes burned at 650 °C, which can be rehydrated easily. Although, the mature pastes that have been burned initially and stored under laboratory conditions cannot be rehydrated, due to the formation of stable products during the storage.

Processes of carbonation of calcium-rich aqueous industrial wastes from acetylene production were performed mimicking rock weathering, using the atmospheric carbon dioxide as reactant. This residue was carbonated exposing it to the air in artificial pools with controlled solid-to-liquid and surface-to-volume ratios, and the efficiency of this simple mineral carbonation process was maximized. Considering realistic values of just one acetylene production plant, the intelligent handling of the calcium-rich waste would make it possible to counteract the emission of around 800t of carbon dioxide per year, so the CO2 emissions of the acetylene production could be completely compensated and its carbon footprint significantly reduced.X-ray diffraction patterns and thermogravimetric analyses reported the conversion, up to 88%, of the calcium hydroxide into calcium carbonate under atmospheric conditions. So, considering a realistic industrial scale-up, 476kg of CO2 could be captured with 1t of dry waste. The morphology of the grains is resolved by electron microscopy, and can be described as needles 15nm wide and 200nm long arranged in grains smaller than 1 micron. We exploit these nanometric textural parameters (nanometric pores and particles having a specific surface area ∼50m2/g) to design an efficient carbon fixation procedure. The aim of this work is to propose this simple carbonation technology, based on aqueous alkaline industrial waste, as a contribution to reducing global CO2 emissions.

Processes of carbonation of calcium-rich aqueous industrial wastes from acetylene production were performed mimicking rock weathering, using the atmospheric carbon dioxide as reactant. This residue was carbonated exposing it to the air in artificial pools with controlled solid-to-liquid and surface-to-volume ratios, and the efficiency of this simple mineral carbonation process was maximized. Considering realistic values of just one acetylene production plant, the intelligent handling of the calcium-rich waste would make it possible to counteract the emission of around 800t of carbon dioxide per year, so the CO2 emissions of the acetylene production could be completely compensated and its carbon footprint significantly reduced.X-ray diffraction patterns and thermogravimetric analyses reported the conversion, up to 88%, of the calcium hydroxide into calcium carbonate under atmospheric conditions. So, considering a realistic industrial scale-up, 476kg of CO2 could be captured with 1t of dry waste. The morphology of the grains is resolved by electron microscopy, and can be described as needles 15nm wide and 200nm long arranged in grains smaller than 1 micron. We exploit these nanometric textural parameters (nanometric pores and particles having a specific surface area ∼50m2/g) to design an efficient carbon fixation procedure. The aim of this work is to propose this simple carbonation technology, based on aqueous alkaline industrial waste, as a contribution to reducing global CO2 emissions.

Lime mortars have, up to a certain extent, a self-healing capacity which may contribute to their durability. Self-healing in lime mortars consists of a process of dissolution, transport and re-precipitation of calcium compounds to heal cracks and fissures. The spontaneous occurrence of self-healing in lime-based mortars is a well known phenomenon; to date, however, little research has been done on its occurrence in the practice. This study aims at gaining a better understanding of the self-healing mechanism in lime-based mortars through the investigation of case studies where self-healing has been observed. On the basis of the results obtained the relevance of the various controlling factors, the way in which they potentially interact, and how they affect the occurrence of self-healing is evaluated. Lime-based mortar samples collected from several case studies were studied. Thin sections were prepared and studied by means of Polarization & Fluorescence Microscopy (PFM). The influence of selected parameters (moisture content, degree of carbonation, binder-sand ratio, binder type, etc.) on the nature (calcium carbonate or calcium hydroxide) and crystal habits of the precipitated products has been investigated. The results obtained indicate that some recurrent patterns exist in the nature and the crystal habits of the re-precipitated products depending, among other factors, on the moisture content and on the degree of carbonation of the mortar.

Processes of carbonation of calcium-rich aqueous industrial wastes from acetylene production were performed mimicking rock weathering, using the atmospheric carbon dioxide as reactant. This residue was carbonated exposing it to the air in artificial pools with controlled solid-to-liquid and surface-to-volume ratios, and the efficiency of this simple mineral carbonation process was maximized. Considering realistic values of just one acetylene production plant, the intelligent handling of the calcium-rich waste would make it possible to counteract the emission of around 800t of carbon dioxide per year, so the CO2 emissions of the acetylene production could be completely compensated and its carbon footprint significantly reduced.X-ray diffraction patterns and thermogravimetric analyses reported the conversion, up to 88%, of the calcium hydroxide into calcium carbonate under atmospheric conditions. So, considering a realistic industrial scale-up, 476kg of CO2 could be captured with 1t of dry waste. The morphology of the grains is resolved by electron microscopy, and can be described as needles 15nm wide and 200nm long arranged in grains smaller than 1 micron. We exploit these nanometric textural parameters (nanometric pores and particles having a specific surface area ∼50m2/g) to design an efficient carbon fixation procedure. The aim of this work is to propose this simple carbonation technology, based on aqueous alkaline industrial waste, as a contribution to reducing global CO2 emissions.

Increasing global cement production faces challenges such as cost increases in energy supply, requirements to reduce CO2 emissions, and the supply of raw materials in sufficient quality and amounts. Worldwide cement manufacturing represents 5% of man-made CO2 emissions, from which 50% is related to chemical process of clinker production, 40% to burning fuel and 10% is split between electricity use and transportation. To conserve natural non-renewable resources and preventing unnecessary landfilling, wastes valorisation as raw materials has been suggested for partially substituting the portland clinker with alternative materials in cement manufacture process and also for using alternative fuels reducing fossil fuels consumption. Nowadays, SCMs are widely used in concrete either in blended cements or added separately in the concrete mixer (where no additional clinkering process is involved) to obtain sustainable or low-CO2 cements. In addition, cementitious solidification/stabilization –S/S- is a useful technique for most toxic elements disposal. Leaching tests and subsequent geochemical modelling are commonly used to investigate pollutants’ release behaviour. Just a few mechanistic studies have been developed so far to assess the role of cement hydrates in the sorption and fixation of oxyanions (As, Cr, Se, Mo, Sb, V and W) considering that important tonnes of hazardous wastes are generated worldwide. Classical studies have focused on suggesting that in highly alkaline systems, solid solution formation with these solid phases is most likely to control retention and release behaviour. However, the role of phases such as CSH and portlandite is poorly known, being both the major hydration products of cementitious materials. In addition to this, the increasing use of supplementary cementitious materials (SCMs) with the aim of producing more sustainable cements poses new questions on the geochemical behaviour of these elements under systems with significantly different mi

Processes of carbonation of calcium-rich aqueous industrial wastes from acetylene production were performed mimicking rock weathering, using the atmospheric carbon dioxide as reactant. This residue was carbonated exposing it to the air in artificial pools with controlled solid-to-liquid and surface-to-volume ratios, and the efficiency of this simple mineral carbonation process was maximized. Considering realistic values of just one acetylene production plant, the intelligent handling of the calcium-rich waste would make it possible to counteract the emission of around 800t of carbon dioxide per year, so the CO2 emissions of the acetylene production could be completely compensated and its carbon footprint significantly reduced.X-ray diffraction patterns and thermogravimetric analyses reported the conversion, up to 88%, of the calcium hydroxide into calcium carbonate under atmospheric conditions. So, considering a realistic industrial scale-up, 476kg of CO2 could be captured with 1t of dry waste. The morphology of the grains is resolved by electron microscopy, and can be described as needles 15nm wide and 200nm long arranged in grains smaller than 1 micron. We exploit these nanometric textural parameters (nanometric pores and particles having a specific surface area ∼50m2/g) to design an efficient carbon fixation procedure. The aim of this work is to propose this simple carbonation technology, based on aqueous alkaline industrial waste, as a contribution to reducing global CO2 emissions.

Processes of carbonation of calcium-rich aqueous industrial wastes from acetylene production were performed mimicking rock weathering, using the atmospheric carbon dioxide as reactant. This residue was carbonated exposing it to the air in artificial pools with controlled solid-to-liquid and surface-to-volume ratios, and the efficiency of this simple mineral carbonation process was maximized. Considering realistic values of just one acetylene production plant, the intelligent handling of the calcium-rich waste would make it possible to counteract the emission of around 800t of carbon dioxide per year, so the CO2 emissions of the acetylene production could be completely compensated and its carbon footprint significantly reduced.X-ray diffraction patterns and thermogravimetric analyses reported the conversion, up to 88%, of the calcium hydroxide into calcium carbonate under atmospheric conditions. So, considering a realistic industrial scale-up, 476kg of CO2 could be captured with 1t of dry waste. The morphology of the grains is resolved by electron microscopy, and can be described as needles 15nm wide and 200nm long arranged in grains smaller than 1 micron. We exploit these nanometric textural parameters (nanometric pores and particles having a specific surface area ∼50m2/g) to design an efficient carbon fixation procedure. The aim of this work is to propose this simple carbonation technology, based on aqueous alkaline industrial waste, as a contribution to reducing global CO2 emissions.

Lime mortars have, up to a certain extent, a self-healing capacity which may contribute to their durability. Self-healing in lime mortars consists of a process of dissolution, transport and re-precipitation of calcium compounds to heal cracks and fissures. The spontaneous occurrence of self-healing in lime-based mortars is a well known phenomenon; to date, however, little research has been done on its occurrence in the practice. This study aims at gaining a better understanding of the self-healing mechanism in lime-based mortars through the investigation of case studies where self-healing has been observed. On the basis of the results obtained the relevance of the various controlling factors, the way in which they potentially interact, and how they affect the occurrence of self-healing is evaluated. Lime-based mortar samples collected from several case studies were studied. Thin sections were prepared and studied by means of Polarization & Fluorescence Microscopy (PFM). The influence of selected parameters (moisture content, degree of carbonation, binder-sand ratio, binder type, etc.) on the nature (calcium carbonate or calcium hydroxide) and crystal habits of the precipitated products has been investigated. The results obtained indicate that some recurrent patterns exist in the nature and the crystal habits of the re-precipitated products depending, among other factors, on the moisture content and on the degree of carbonation of the mortar.

Portlandite, one of the main products of cement hydration and which normally comprises about 25% of the paste, is a principal buffer responsible for maintaining the high pH in response to interactions between the paste and its service environment. The kinetics of these environmentally - conditioned reactions are often important. However the present approach to kinetics is handicapped by lack of fundamental data. For example, we lack data on the kinetics of dissolution of portlandite. Portlandite is congruently soluble and its dissolution rate and mechanism are reported. Single crystals of portlandite have been grown and their effective surface area measured. Dissolution rates are reported into initially pure water as functions of calcium hydroxide concentration. The impacts of low concentration of other ions, e.g., chloride, on congruent dissolution kinetics are reported.

Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees., The reaction between a spent fluid cracking catalyst (FC3R) residue and portlandite was monitored over 56 days using several material characterisation techniques. The results showed that the residue was heterogeneous and composed of reactive and non-reactive fractions and that both fractions contained silicon and aluminium. After 56 days, the development of C-S-H gel was evident; part of the catalyst residue was pozzolanic. The CH combination could be monitored by thermogravimetry or X-ray diffraction, by measuring the signal corresponding to CH. However, due to the low crystallinity of cementing products and their complex stoichiometry, the above-mentioned techniques were less able to characterise C-A-S-H. However, nuclear magnetic resonance techniques allowed the evolution of the pozzolanic reaction to be evaluated and the hydrate products to be characterised. Thomas Telford Ltd & 2011.

Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees., The reaction between a spent fluid cracking catalyst (FC3R) residue and portlandite was monitored over 56 days using several material characterisation techniques. The results showed that the residue was heterogeneous and composed of reactive and non-reactive fractions and that both fractions contained silicon and aluminium. After 56 days, the development of C-S-H gel was evident; part of the catalyst residue was pozzolanic. The CH combination could be monitored by thermogravimetry or X-ray diffraction, by measuring the signal corresponding to CH. However, due to the low crystallinity of cementing products and their complex stoichiometry, the above-mentioned techniques were less able to characterise C-A-S-H. However, nuclear magnetic resonance techniques allowed the evolution of the pozzolanic reaction to be evaluated and the hydrate products to be characterised. Thomas Telford Ltd & 2011.

Calcium leaching is a degradation process that consists in the progressive dissolution of the cement paste as a consequence of the migration of the calcium ions to the aggressive solution. Although it is a well known phenomenon, a way of reducing it has not been found yet. The aim of this work is to prove how the addition of small amounts of silica nanoparticles to the cement paste can induce such reduction. The experimental results obtained have shown that nanosilica increases the strength of the cement paste about a 30% in cured samples and more than a 100% in the asymptotically leached ones. At the level of the structure of the C–S–H gel, silica nanoparticles increase the average length of the silicate chains and reduce their polymerization as calcium dissolves. An important decrease of the degradation in terms of porosity and amount of calcium lost has also been observed.

The hydration products in two aged cement pastes (DTA/DTG/TG) were compared with those in fresh ones (static heating, SH) and were also studied by mass spectrometry (MS), IR and thermo XRD-analysis. The products considered here were: the sorbed water, the CSH gel including hydrates, portlandite, calcite, aragonite and vaterite. Except carbonates their content was higher in the stronger paste C-43, than in C-33, but lowered with ageing (only the CSH gel water remained approximately unchanged). The sorbed water content became with time lower and similar in both pastes (it evaporated up to 155-185°C in TG); the escape of the rest moved to higher temperatures (500-700°C). The three DTG peaks at 200-400°C indicated jennite-like phase in the CSH gel; the mass loss (155-460°C) was higher on ageing due to development of organic matter, especially in C-43 (DTA, TG, IR). Portlandite content changed little and carbonate content increased considerably. They decomposed in air at 470 and 720-740°C, in argon at 450 and 680-710°C and in vacuum at 400 and 630°C, respectively (DTG peak, XRD). Between 500 and 700°C the simultaneous evolution of H2O and CO2was observed by MS, which is attributed to dehydroxylation of jennite-like phase and/or to decomposition of some carbonate hydrate and/or hydrocarbonate (three peaks on CO2evolution curve, MS). The d(001) peak of portlandite exceeded the nominal value and will be analyzed separately. © 2005 Akadémiai Kiadó, Budapest.

Práce se zabývá studiem karbonatace portlanditu pomocí in-situ rentgenové difrakční analýzy. Karbonatace portlanditu probíhá v betonových konstrukcích a je již poměrně široce popsána. Je zodpovědná za korozi a degradaci železobetonových stavebních prvků, a tím pádem je její vliv vnímán velmi negativně. Cílem této práce je určení ideálních podmínek pro průběh karbonatace portlanditu. V práci je sledován průběh karbonatace v závislosti na relativní vlhkosti a teplotě, který je následně vyhodnocován pomocí termických analýz (TG/DTA) a rentgenové práškové difrakce., Thesis deals with carbonation of portlandite using in-situ X-ray diffraction analysis. The carbonation of portlandite progress in concrete structures and it is already quite widely discussed. It is responsible for corrosion and degradation of reinforced concrete elements, and thus its influence is perceived very negatively. The main goal of this work is to determine the ideal conditions for the progress of carbonation of portlandite. In this work the progress of carbonation depending on the relative humidity and temperature was observated. The amount of carbonated portlandite was evaluated by means of thermal analyzes (TG / DTA) and X-ray analysis.

V tejto práci bol skúmaný mechanizmus a kinetika procesu suchej karbonatácie portlanditu. Úvodná časť práce oboznamuje čitateľa o základných teoretických informáciách štúdia kinetiky, mechanizmu a o samotných analýzach. V experimentálnej časti čitateľa oboznamuje o použitých metódach a o použitom postupe vyhodnocovania kinetiky a mechanizmu. V poslednej kapitole sú interpretované výsledky štúdia práce aj s diskusiou a analýzami použitej vzorky., The main goal of this work, is study of kinetics and mechanism of gas-solid carbonation of portlandit. The introduction part of the thesis acquaints the reader with basic theoretical information about the study of kinetics, mechanism and the analyses themselves. In the experimental part, the reader is acquainted with the methods and procedures used to evaluate the kinetics and mechanism. The last chapter interprets the results of the study, with discusion about results and analysis of the used sample.

Diplomová práce se zabývá studiem vysokopevnostních betonů s vysokým obsahem elektrárenských popílků. V teoretické části jsou postupně rozebrány hlavní principy a charakteristiky vysokopevnostních a vysokopopílkových betonů. Dále byla dle zjištěných poznatků popsána technologie vysokopevnostních vysokopopílkových betonů, včetně principů dosažení vysoké pevnosti. Na základě zjištěných poznatků byly v experimentální části navrženy a vytvořeny vysokopevnostní, vysokopopílkové betony pro specifické pevnosti v tlaku. Tyto betony pak byly podrobeny řadě zkoušek., This diploma thesis deals with the study of high-strength, high-volume fly ash concrete. The theoretical part of this thesis focuses on the detailed characteristic and main principles of high-strength concrete, high-volume fly ash concrete. In addition, according to the findings, the technology of high-strength and high-volume fly ash concrete, including principles of high strength, has been described. On the basis of the findings, high-strength, high-volume fly ash concrete for specific compressive strengths has been designed and created in the experimental section. These concretes were then subjected to a number of tests.

Práce se zabývá studiem karbonatace portlanditu pomocí in-situ rentgenové difrakční analýzy. Karbonatace portlanditu probíhá v betonových konstrukcích a je již poměrně široce popsána. Je zodpovědná za korozi a degradaci železobetonových stavebních prvků, a tím pádem je její vliv vnímán velmi negativně. Cílem této práce je určení ideálních podmínek pro průběh karbonatace portlanditu. V práci je sledován průběh karbonatace v závislosti na relativní vlhkosti a teplotě, který je následně vyhodnocován pomocí termických analýz (TG/DTA) a rentgenové práškové difrakce., Thesis deals with carbonation of portlandite using in-situ X-ray diffraction analysis. The carbonation of portlandite progress in concrete structures and it is already quite widely discussed. It is responsible for corrosion and degradation of reinforced concrete elements, and thus its influence is perceived very negatively. The main goal of this work is to determine the ideal conditions for the progress of carbonation of portlandite. In this work the progress of carbonation depending on the relative humidity and temperature was observated. The amount of carbonated portlandite was evaluated by means of thermal analyzes (TG / DTA) and X-ray analysis.

Autoklávovaný pórobeton je využívaným stavebním materiálem, zejména pro jeho tepelně izolační vlastnosti. Během autoklávování dochází v mikrostruktuře pórobetonu ke vzniku krystalických CSH fází, především tobermoritu. Vstupními látkami jsou oxid vápenatý a oxid křemičitý. Mimo běžně používané suroviny, je možné pro výrobu použít suroviny druhotné, bohaté na oxid křemičitý. Využití druhotných surovin dává příležitost, aby stavební průmysl byl ekologičtější k životnímu prostředí. Dalším přínosem je snížení finančních nákladů. V práci je zkoumán vliv jednotlivých druhotných surovin na mikrostrukturu. Byl použit vysokoteplotní popílek, fluidní popílek, škvára, mleté obalové sklo a zeolit. Suroviny byly míchány s nehašeným vápnem v molárním poměru oxidu vápenatého k oxidu křemičitému 0,73 a 1,0. Pro syntézu tobermoritu v laboratorních podmínkách bylo využito autoklávovacích kapslí. Autoklávování probíhalo při teplotách 170 a 190 °C s hydrotermální výdrží 4, 8 a 16 hodin. Nejvýznamnější vliv na mikrostrukturu vykázal vysokoteplotní popílek, naopak největší vliv na mechanické vlastnosti, je připisováno mletému obalovému sklu., Autoclaved aerated concrete is a used building material, especially for its thermal insulating properties. During autoclaving, an aerated concrete microstructure produces crystalline CSH phases, primarily tobermorite. The ingoing substances are calcium oxide and silica. In addition to commonly used raw materials, secondary raw materials rich in silicon dioxide can be used for production. The use of secondary raw materials gives the opportunity for the construction industry to be more environmentally friendly. Another benefit is the reduction of financial costs. The work explores the influence of individual secondary raw materials on the microstructure. High-temperature fly ash, fluid fly ash, cinder, ground glass and zeolite were used The raw materials were mixed with unalloyed lime at a molar ratio of calcium oxide to silicon dioxide of 0.73 and 1.0. Autoclaving capsules were used to synthesize tobermorite under laboratory conditions. Autoclave was performed at 170 °C and 190 °C with hydrothermal durations of 4, 8 and 16 hours. The most important influence on the microstructure was high-temperature fly ash, on the contrary, the greatest influence on the mechanical properties is attributed to the ground glass.

V tejto práci bol skúmaný mechanizmus a kinetika procesu suchej karbonatácie portlanditu. Úvodná časť práce oboznamuje čitateľa o základných teoretických informáciách štúdia kinetiky, mechanizmu a o samotných analýzach. V experimentálnej časti čitateľa oboznamuje o použitých metódach a o použitom postupe vyhodnocovania kinetiky a mechanizmu. V poslednej kapitole sú interpretované výsledky štúdia práce aj s diskusiou a analýzami použitej vzorky., The main goal of this work, is study of kinetics and mechanism of gas-solid carbonation of portlandit. The introduction part of the thesis acquaints the reader with basic theoretical information about the study of kinetics, mechanism and the analyses themselves. In the experimental part, the reader is acquainted with the methods and procedures used to evaluate the kinetics and mechanism. The last chapter interprets the results of the study, with discusion about results and analysis of the used sample.

Ettringite is a hydrous calcium sulphoaluminate of formula Ca6Al2(SO4)3(OH)12.26H2O and belongs to a larger group of 13 minerals, the ettringite group. The mineral has first been described in 1874 in calcareous xenoliths in volcanic lava from the Eifel massif in Germany. It is a major constituent of cement, a stabiliser of pollutants, and a whitening agent in paper and paints, known as 'white satin'. Its crystal structure has been established and numerous substitutions can potentially be synthesised. Natural analogues known in cements have been observed frequently, such as: jennite with a crystal structure used as a model for hydrous calcium silicates (C-S-H) in cements; katoite which is a hydrogarnet; and portlandite formed from hydration of lime. Ettringite is also known near contact metamorphism and hydrothermal processes. In France, it is found in the porcelanites of Boissejour in the Puy-de-Dome. It is also frequently associated with mine waste. Apart from its uses it can also prove extremely damaging in concrete, known as Delayed Ettringite Formation (DEF), where crystals fill the cracks left after swelling and drying of cement paste., Ettringite is a hydrous calcium sulphoaluminate of formula Ca6Al2(SO4)3(OH)12.26H2O and belongs to a larger group of 13 minerals, the ettringite group. The mineral has first been described in 1874 in calcareous xenoliths in volcanic lava from the Eifel massif in Germany. It is a major constituent of cement, a stabiliser of pollutants, and a whitening agent in paper and paints, known as 'white satin'. Its crystal structure has been established and numerous substitutions can potentially be synthesised. Natural analogues known in cements have been observed frequently, such as: jennite with a crystal structure used as a model for hydrous calcium silicates (C-S-H) in cements; katoite which is a hydrogarnet; and portlandite formed from hydration of lime. Ettringite is also known near contact metamorphism and hydrothermal processes. In France, it is found in the porcelanites of Boissejour in the Puy-de-Dome. It is also frequently associated with mine waste. Apart from its uses it can also prove extremely damaging in concrete, known as Delayed Ettringite Formation (DEF), where crystals fill the cracks left after swelling and drying of cement paste.