This paper presents an approach to the use and interpretation of tests on mortar samples when res... more This paper presents an approach to the use and interpretation of tests on mortar samples when restoring historic masonry. It is largely based on the work performed by the former RILEM technical committee 167-COM, Characterisation of old mortars, closed in 2003, and the ongoing committee 203-RHM, Repair mortars for historic masonry. The focus of the present paper is on the decision process: what to test and how to interpret the test results.
Five different Self-Compacting Concrete (SCC) compositions, composed of three different types of ... more Five different Self-Compacting Concrete (SCC) compositions, composed of three different types of mineral additions (limestone powder, quartz powder and fly ash) and two types of cement (CEM I 52.5 R HES and CEM III/A 42.5 N LA), were exposed to a continuous immersion in a H2SO4-solution (pH ~ 1.7) for 26 weeks. Rate of attack was estimated by means of mass variation versus time. Microstructural degradation was investigated using polarising light microscope and scanning electron microscope. SCC containing CEM I and limestone powder gives better resistance to sulphuric acid attack compared to the traditionally vibrated concrete (TC) and SCC compositions with fly ash and quartz powder due to the buffering effect of calcium carbonate (CaCO3) under acidic conditions. The extent of damage is greater in SCC incorporating CEM I-fly ash, CEM I-quartz powder and CEM III/A-limestone powder despite the presence of CaCO3 in the latter. With the inward movement of the acid attack from the surface...
Carbonation of lime binders has been studied using a carbonation set-up combined with in-situ XRD... more Carbonation of lime binders has been studied using a carbonation set-up combined with in-situ XRD analysis in order to follow the real-time modification in portlandite and calcite phases while measuring the reaction kinetics. Accelerated carbonation was carried out in ...
h i g h l i g h t s " Carbonation of lime is followed up via CO 2 uptake and in situ mineral phas... more h i g h l i g h t s " Carbonation of lime is followed up via CO 2 uptake and in situ mineral phase modifications. " Carbonation reaction is initially rapid and chemically controlled on the exposed surface. " CO 2 -diffusion controlled regime occurs through the carbonated layer at a lower rate. " Lime putty carbonates faster than lime hydrate due to the morphology properties of portlandite crystals. " The rate of carbonation reaction is independent from the CO 2 gas concentration within the limits tested.
Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RH... more Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RHA) and lime in different compositions were studied with mechanical strength, mercury intrusion porosimetry, thermal analysis and SEM. When cement is partially replaced with RHA and lime, hardening occurs as a result of combined hydration, pozzolanic reaction and carbonation reaction. While hydration of cement contributes to the early strength development of the mortars, carbonation is much more pronounced at later stage with the decrease in the cement content in the mortar and the increase in the porosity of the mortars. RHA-cement mortars indicated a long-term strength development, which is lower than that of the reference cement mortar. This was attributed to the high water demand of the blended mortars due to the porous RHA grains, which resulted in an increase in their porosity. Strength reduction was recorded at the very early stage for RHA-cement-lime mortars containing 10%-wt cement. This has been explained with the insufficient cement content, destructive effect of the calcium carbonate phases on the initially hydrated cement phases and partial carbonation of the initially hydrated phases.
The morphology of calcium carbonate crystals has been studied at 20ºC during accelerated carbonat... more The morphology of calcium carbonate crystals has been studied at 20ºC during accelerated carbonation using 20% and 100% volume CO2 concentrations at~ 95% RH for lime pastes. Accelerated carbonation resulted in precipitation of calcite crystals with a habit and ...
Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RH... more Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RHA) and lime in different compositions were studied with mortars using thermal analysis, mechanical strength and SEM. When cement is partially replaced with RHA and ...
A study of breakthrough curves for cations usually found in acid mine drainage (Pb 2+ , Cu 2+ , Z... more A study of breakthrough curves for cations usually found in acid mine drainage (Pb 2+ , Cu 2+ , Zn 2+ and H + ) and municipal wastewater (NH 4 + ) have been conducted on some natural zeolitic tuffs. The zeolitic tuffs used in this study are: three zeolitic tuffs from Cayo Formation, Guayaquil (Ecuador), characterized by Xray diffraction as clinoptilolite (sample CLI-1) and heulandite (samples HEU-1 and HEU-2)-rich tuffs, and two zeolitic tuffs from Parnaiba Basin, Belem do Pará (Brazil), characterized as stilbite-rich tuffs (samples STI-1 and STI-2). The clinoptilolite sample CLI-1 shows an exceedingly good exchange capacities for Pb 2+ and NH 4 + as received, and also a very high exchange capacity for Cu 2+ and Zn 2+ when conditioned with 2 M sodium chloride, with much higher values than those reported in the literature for other clinioptilolite ores. A general order of effective cation exchange capacity could be inferred from breakthrough curves on these zeolitic tuffs:
Disintegration of stainless-steel slag during cooling is caused by the β→γ transformation of dica... more Disintegration of stainless-steel slag during cooling is caused by the β→γ transformation of dicalcium silicate (2CaO·SiO2 or C2S). It is well established that disintegration can be avoided by borate additions, which are commonly believed to stabilize the high-temperature polymorphs by forming a solid solution with C2S. In this study, the borate distributions in slowly cooled synthetic and industrial slag samples are determined. The slag microstructures are characterized using electron probe microanalysis (EPMA), quantitative X-ray diffraction (QXRD), and wavelength dispersive spectroscopy (WDS). The results show that only a limited fraction of the added borates forms a solid solution with the C2S phase, while the main fraction is found in a calcium borosilicate phase. In combination with literature data, this suggests that slag stabilization involves more than the chemical stabilization of the high-temperature C2S polymorphs.
ABSTRACT A thorough characterization of the mineralogy and detailed clay mineralogy is an importa... more ABSTRACT A thorough characterization of the mineralogy and detailed clay mineralogy is an important tool in scientific research and industrial applications of shales. It helps to understand the geological history of the deposits and significantly contributes to solving specific geological problems. In three separate examples, it is demonstrated how the clay mineralogy of fine-grained deposits during different stages of diagenesis is characterized in detail. In a first example, clay minerals are used as provenance indicators in recent muds of the Belgian North Sea. A second example handles on the detailed clay mineralogy of early diagenetic Ypresian clays which are currently being researched as possible host rock for radioactive waste disposal. A third example involves the mineralogical characterization of a later diagenetic potential shale gas play in Belgium.
Natural clay-sized glauconite has the same mineralogical composition as sand-sized glauconite pel... more Natural clay-sized glauconite has the same mineralogical composition as sand-sized glauconite pellets but occurs in d 060 values ranging between 1.513 Å and 1.519 Å. Clay-sized glauconite was not neoformed but formed by the disintegration of sandsized glauconite pellets which were abraded or broken up during short-distance transport within the sedimentary basin or over the hinterland. Even in an environment where authigenic glauconite pellets occur, minimal transport over transgressive surfaces is sufficient to produce clay-sized glauconite. Furthermore, clay-sized glauconite can be eroded from marine deposits and subsequently resedimented in estuarine deposits. Clay-sized glauconite is, therefore, a proxy for the transport intensity of pelletal glauconite in energetic depositional environments and, moreover, indicates reworking in such deposits which lack pelletal glauconite.
Mineral carbonation involves the capture of carbon dioxide in a mineral form. The principal aim a... more Mineral carbonation involves the capture of carbon dioxide in a mineral form. The principal aim and advantage of this approach is the chemical stability (reduced free lime and improved leaching resistance) and storage safety of mineral carbonates, the opportunities for process integration presented by the technology, and the potential for valorisation of otherwise low-value resources (virgin or waste) into useful products. A class of waste materials that has good potential for implementation as a feed material for mineral carbonation are steel slags. An integrated on-site mineral carbonation approach is envisaged as a possibly economically favourable solution in this work.
Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RH... more Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RHA) and lime in different compositions were studied with mortars using thermal analysis, mechanical strength and SEM. When cement is partially replaced with RHA and lime, hardening occurs as a result of combined hydration, pozzolanic reaction and carbonation reaction. While hydration of cement contributes to the early strength development of the mortars, carbonation is much more pronounced at later stage with the decrease in the cement content and increase in the porosity of the mortars. RHA-cement mortars indicated a long-term strength development, which is lower than that of the reference cement mortar. This was attributed to their higher porosity due to the high water demand of the porous RHA grains. Strength reduction was recorded at the very early stage for RHA-cement-lime mortars containing 10%-wt cement as well as RHA-lime mortars. This has been explained with the insufficient ceme...
Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RH... more Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RHA) and lime in different compositions were studied with mechanical strength, mercury intrusion porosimetry, thermal analysis and SEM. When cement is partially replaced with RHA and lime, hardening occurs as a result of combined hydration, pozzolanic reaction and carbonation reaction. While hydration of cement contributes to the early strength development of the mortars, carbonation is much more pronounced at later stage with the decrease in the cement content in the mortar and the increase in the porosity of the mortars. RHA-cement mortars indicated a long-term strength development, which is lower than that of the reference cement mortar. This was attributed to the high water demand of the blended mortars due to the porous RHA grains, which resulted in an increase in their porosity. Strength reduction was recorded at the very early stage for RHA-cement-lime mortars containing 10%-wt ceme...
Carbonation of lime binders has been studied using a carbonation set-up combined with in-situ XRD... more Carbonation of lime binders has been studied using a carbonation set-up combined with in-situ XRD analysis in order to follow the real-time modification in portlandite and calcite phases while measuring the reaction kinetics. Accelerated carbonation was carried out in a 100% CO 2 atmosphere at ~95% RH using lime pastes at different water contents. XRD results indicated that carbonation reaction initiated immediately with the uptake of CO 2 by the water film and the precipitation of calcite crystals on the sample surface. At the initial stage, the reaction was limited by this water film on the sample surface, hindering the CO 2 diffusion through the sample thickness. Upon drying, carbonation was accelerated through this diffusion process and resulted in a complete precipitation of calcite crystals on the sample surface while the reaction continued along the sample thickness at a reduced rate. Continuous measurement of RH during carbonation evidenced the acceleration of the reaction w...
The morphology of calcium carbonate crystals has been studied at 20ºC during accelerated carbonat... more The morphology of calcium carbonate crystals has been studied at 20ºC during accelerated carbonation using 20% and 100 % volume CO 2 concentrations at ~95% R.H. for lime pastes. Accelerated carbonation resulted in precipitation of calcite crystals with a habit and morphology similar on the sample surface but different along the sample thickness, depending on the lime type and CO 2 concentration. Micrometer-sized rhombohedral calcite crystals precipitated on the sample surface in 100% CO 2 atmosphere while the crystals were sub-micrometer-sized rhombohedral in the 20% CO 2 atmosphere. Through the sample thickness, the carbonated profile was composed of scalenohedral calcite crystals with cracked/corroded surfaces that were disintegrated into nanometer-sized rhombohedra. It has been found that scalenohedral calcite undergoes a significant modification to rhombohedral when exposed to high CO 2 concentrations. This can be explained with a dissolution-reprecipitation process under excess...
This paper presents an approach to the use and interpretation of tests on mortar samples when res... more This paper presents an approach to the use and interpretation of tests on mortar samples when restoring historic masonry. It is largely based on the work performed by the former RILEM technical committee 167-COM, Characterisation of old mortars, closed in 2003, and the ongoing committee 203-RHM, Repair mortars for historic masonry. The focus of the present paper is on the decision process: what to test and how to interpret the test results.
Five different Self-Compacting Concrete (SCC) compositions, composed of three different types of ... more Five different Self-Compacting Concrete (SCC) compositions, composed of three different types of mineral additions (limestone powder, quartz powder and fly ash) and two types of cement (CEM I 52.5 R HES and CEM III/A 42.5 N LA), were exposed to a continuous immersion in a H2SO4-solution (pH ~ 1.7) for 26 weeks. Rate of attack was estimated by means of mass variation versus time. Microstructural degradation was investigated using polarising light microscope and scanning electron microscope. SCC containing CEM I and limestone powder gives better resistance to sulphuric acid attack compared to the traditionally vibrated concrete (TC) and SCC compositions with fly ash and quartz powder due to the buffering effect of calcium carbonate (CaCO3) under acidic conditions. The extent of damage is greater in SCC incorporating CEM I-fly ash, CEM I-quartz powder and CEM III/A-limestone powder despite the presence of CaCO3 in the latter. With the inward movement of the acid attack from the surface...
Carbonation of lime binders has been studied using a carbonation set-up combined with in-situ XRD... more Carbonation of lime binders has been studied using a carbonation set-up combined with in-situ XRD analysis in order to follow the real-time modification in portlandite and calcite phases while measuring the reaction kinetics. Accelerated carbonation was carried out in ...
h i g h l i g h t s " Carbonation of lime is followed up via CO 2 uptake and in situ mineral phas... more h i g h l i g h t s " Carbonation of lime is followed up via CO 2 uptake and in situ mineral phase modifications. " Carbonation reaction is initially rapid and chemically controlled on the exposed surface. " CO 2 -diffusion controlled regime occurs through the carbonated layer at a lower rate. " Lime putty carbonates faster than lime hydrate due to the morphology properties of portlandite crystals. " The rate of carbonation reaction is independent from the CO 2 gas concentration within the limits tested.
Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RH... more Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RHA) and lime in different compositions were studied with mechanical strength, mercury intrusion porosimetry, thermal analysis and SEM. When cement is partially replaced with RHA and lime, hardening occurs as a result of combined hydration, pozzolanic reaction and carbonation reaction. While hydration of cement contributes to the early strength development of the mortars, carbonation is much more pronounced at later stage with the decrease in the cement content in the mortar and the increase in the porosity of the mortars. RHA-cement mortars indicated a long-term strength development, which is lower than that of the reference cement mortar. This was attributed to the high water demand of the blended mortars due to the porous RHA grains, which resulted in an increase in their porosity. Strength reduction was recorded at the very early stage for RHA-cement-lime mortars containing 10%-wt cement. This has been explained with the insufficient cement content, destructive effect of the calcium carbonate phases on the initially hydrated cement phases and partial carbonation of the initially hydrated phases.
The morphology of calcium carbonate crystals has been studied at 20ºC during accelerated carbonat... more The morphology of calcium carbonate crystals has been studied at 20ºC during accelerated carbonation using 20% and 100% volume CO2 concentrations at~ 95% RH for lime pastes. Accelerated carbonation resulted in precipitation of calcite crystals with a habit and ...
Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RH... more Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RHA) and lime in different compositions were studied with mortars using thermal analysis, mechanical strength and SEM. When cement is partially replaced with RHA and ...
A study of breakthrough curves for cations usually found in acid mine drainage (Pb 2+ , Cu 2+ , Z... more A study of breakthrough curves for cations usually found in acid mine drainage (Pb 2+ , Cu 2+ , Zn 2+ and H + ) and municipal wastewater (NH 4 + ) have been conducted on some natural zeolitic tuffs. The zeolitic tuffs used in this study are: three zeolitic tuffs from Cayo Formation, Guayaquil (Ecuador), characterized by Xray diffraction as clinoptilolite (sample CLI-1) and heulandite (samples HEU-1 and HEU-2)-rich tuffs, and two zeolitic tuffs from Parnaiba Basin, Belem do Pará (Brazil), characterized as stilbite-rich tuffs (samples STI-1 and STI-2). The clinoptilolite sample CLI-1 shows an exceedingly good exchange capacities for Pb 2+ and NH 4 + as received, and also a very high exchange capacity for Cu 2+ and Zn 2+ when conditioned with 2 M sodium chloride, with much higher values than those reported in the literature for other clinioptilolite ores. A general order of effective cation exchange capacity could be inferred from breakthrough curves on these zeolitic tuffs:
Disintegration of stainless-steel slag during cooling is caused by the β→γ transformation of dica... more Disintegration of stainless-steel slag during cooling is caused by the β→γ transformation of dicalcium silicate (2CaO·SiO2 or C2S). It is well established that disintegration can be avoided by borate additions, which are commonly believed to stabilize the high-temperature polymorphs by forming a solid solution with C2S. In this study, the borate distributions in slowly cooled synthetic and industrial slag samples are determined. The slag microstructures are characterized using electron probe microanalysis (EPMA), quantitative X-ray diffraction (QXRD), and wavelength dispersive spectroscopy (WDS). The results show that only a limited fraction of the added borates forms a solid solution with the C2S phase, while the main fraction is found in a calcium borosilicate phase. In combination with literature data, this suggests that slag stabilization involves more than the chemical stabilization of the high-temperature C2S polymorphs.
ABSTRACT A thorough characterization of the mineralogy and detailed clay mineralogy is an importa... more ABSTRACT A thorough characterization of the mineralogy and detailed clay mineralogy is an important tool in scientific research and industrial applications of shales. It helps to understand the geological history of the deposits and significantly contributes to solving specific geological problems. In three separate examples, it is demonstrated how the clay mineralogy of fine-grained deposits during different stages of diagenesis is characterized in detail. In a first example, clay minerals are used as provenance indicators in recent muds of the Belgian North Sea. A second example handles on the detailed clay mineralogy of early diagenetic Ypresian clays which are currently being researched as possible host rock for radioactive waste disposal. A third example involves the mineralogical characterization of a later diagenetic potential shale gas play in Belgium.
Natural clay-sized glauconite has the same mineralogical composition as sand-sized glauconite pel... more Natural clay-sized glauconite has the same mineralogical composition as sand-sized glauconite pellets but occurs in d 060 values ranging between 1.513 Å and 1.519 Å. Clay-sized glauconite was not neoformed but formed by the disintegration of sandsized glauconite pellets which were abraded or broken up during short-distance transport within the sedimentary basin or over the hinterland. Even in an environment where authigenic glauconite pellets occur, minimal transport over transgressive surfaces is sufficient to produce clay-sized glauconite. Furthermore, clay-sized glauconite can be eroded from marine deposits and subsequently resedimented in estuarine deposits. Clay-sized glauconite is, therefore, a proxy for the transport intensity of pelletal glauconite in energetic depositional environments and, moreover, indicates reworking in such deposits which lack pelletal glauconite.
Mineral carbonation involves the capture of carbon dioxide in a mineral form. The principal aim a... more Mineral carbonation involves the capture of carbon dioxide in a mineral form. The principal aim and advantage of this approach is the chemical stability (reduced free lime and improved leaching resistance) and storage safety of mineral carbonates, the opportunities for process integration presented by the technology, and the potential for valorisation of otherwise low-value resources (virgin or waste) into useful products. A class of waste materials that has good potential for implementation as a feed material for mineral carbonation are steel slags. An integrated on-site mineral carbonation approach is envisaged as a possibly economically favourable solution in this work.
Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RH... more Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RHA) and lime in different compositions were studied with mortars using thermal analysis, mechanical strength and SEM. When cement is partially replaced with RHA and lime, hardening occurs as a result of combined hydration, pozzolanic reaction and carbonation reaction. While hydration of cement contributes to the early strength development of the mortars, carbonation is much more pronounced at later stage with the decrease in the cement content and increase in the porosity of the mortars. RHA-cement mortars indicated a long-term strength development, which is lower than that of the reference cement mortar. This was attributed to their higher porosity due to the high water demand of the porous RHA grains. Strength reduction was recorded at the very early stage for RHA-cement-lime mortars containing 10%-wt cement as well as RHA-lime mortars. This has been explained with the insufficient ceme...
Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RH... more Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RHA) and lime in different compositions were studied with mechanical strength, mercury intrusion porosimetry, thermal analysis and SEM. When cement is partially replaced with RHA and lime, hardening occurs as a result of combined hydration, pozzolanic reaction and carbonation reaction. While hydration of cement contributes to the early strength development of the mortars, carbonation is much more pronounced at later stage with the decrease in the cement content in the mortar and the increase in the porosity of the mortars. RHA-cement mortars indicated a long-term strength development, which is lower than that of the reference cement mortar. This was attributed to the high water demand of the blended mortars due to the porous RHA grains, which resulted in an increase in their porosity. Strength reduction was recorded at the very early stage for RHA-cement-lime mortars containing 10%-wt ceme...
Carbonation of lime binders has been studied using a carbonation set-up combined with in-situ XRD... more Carbonation of lime binders has been studied using a carbonation set-up combined with in-situ XRD analysis in order to follow the real-time modification in portlandite and calcite phases while measuring the reaction kinetics. Accelerated carbonation was carried out in a 100% CO 2 atmosphere at ~95% RH using lime pastes at different water contents. XRD results indicated that carbonation reaction initiated immediately with the uptake of CO 2 by the water film and the precipitation of calcite crystals on the sample surface. At the initial stage, the reaction was limited by this water film on the sample surface, hindering the CO 2 diffusion through the sample thickness. Upon drying, carbonation was accelerated through this diffusion process and resulted in a complete precipitation of calcite crystals on the sample surface while the reaction continued along the sample thickness at a reduced rate. Continuous measurement of RH during carbonation evidenced the acceleration of the reaction w...
The morphology of calcium carbonate crystals has been studied at 20ºC during accelerated carbonat... more The morphology of calcium carbonate crystals has been studied at 20ºC during accelerated carbonation using 20% and 100 % volume CO 2 concentrations at ~95% R.H. for lime pastes. Accelerated carbonation resulted in precipitation of calcite crystals with a habit and morphology similar on the sample surface but different along the sample thickness, depending on the lime type and CO 2 concentration. Micrometer-sized rhombohedral calcite crystals precipitated on the sample surface in 100% CO 2 atmosphere while the crystals were sub-micrometer-sized rhombohedral in the 20% CO 2 atmosphere. Through the sample thickness, the carbonated profile was composed of scalenohedral calcite crystals with cracked/corroded surfaces that were disintegrated into nanometer-sized rhombohedra. It has been found that scalenohedral calcite undergoes a significant modification to rhombohedral when exposed to high CO 2 concentrations. This can be explained with a dissolution-reprecipitation process under excess...
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