Papers by Lourdes Gisell Puchoc Soriano
Materials & Design, 2014
The reduction in Portland cement consumption means lower CO 2 emissions. Partial replacement of P... more The reduction in Portland cement consumption means lower CO 2 emissions. Partial replacement of Portland cement by pozzolans such as fly ash has its limitations due to the quantity of calcium hydroxide generated in the mix. In this work we have studied the contribution of the addition of hydrated lime to Portland cement + fly ash systems. We have also studied several levels of cement replacement, ranging from 15% to 75%. The best mechanical results were obtained replacing 50% of Portland cement by the same amount of fly ash plus the addition of hydrated lime (20% respect to the amount of fly ash). In these systems, an acidbase self-neutralization of the matrix has occurred through a pozzolanic reaction of fly ash with portlandite liberated in the hydration of Portland cement and the added hydrated lime. It has been identified for these mixtures a significant amount of hydrated gehlenite, typical reaction product from rich-alumina pozzolans.
SPIE Proceedings, 2014
ABSTRACT Frost resistance of concrete is a major concern in cold regions. RILEM (International un... more ABSTRACT Frost resistance of concrete is a major concern in cold regions. RILEM (International union of laboratories and experts in construction materials, systems and structures) recommendations provide two alternatives for evaluating frost damage by nondestructive evaluation methods for concrete like materials. The first method is based on the ultrasonic pulse velocity measurement, while the second alternative technique is based on the resonant vibration test. In this study, we monitor the frost damage in Portland cement mortar samples with water to cement ratio of 0.5 and aggregate to cement ratio of 3. The samples are completely saturated by water and are frozen for 24 hours at -25°C. The frost damage is monitored after 0, 5, 10, 15 and 20 freezing-thawing cycles by nonlinear impact resonance acoustic spectroscopy (NIRAS). The results obtained are compared with those obtained by resonant vibration tests, the second alternative technique recommended by RILEM. The obtained results show that NIRAS is more sensitive to early stages of damage than the standard resonant vibration tests.
Journal of Thermal Analysis and Calorimetry, 2015
Thermogravimetric analysis (TG) is one of the most common instrumental techniques used for the ch... more Thermogravimetric analysis (TG) is one of the most common instrumental techniques used for the characterization of pastes, mortars and concretes based on both calcium hydroxide or Portland cement. Important information about pozzolanic materials can be assessed concerning to calcium hydroxide consumption and the formation of new hydrated products. Nevertheless, in some cases, problems associated to the overlapped decomposition processes for hydrates difficult the analysis of obtained data. In this paper the use of high resolution thermogravimetric analysis (HRTG), a powerful technique that allows separating decomposition processes in analysis of hydrated binders, was performed for spent FCC catalyst-Portland cement pastes. These pastes were monitored for 1, 4, 8 hours and 1, 2, 3, 7 and 28 curing days. In order to study the influence of the pozzolanic material (spent FCC catalyst), Portland cement replacements of 5, 15 and 30 % by mass were carried out. The presence of spent FCC catalyst in blended pastes modified the amount and the nature of the formed hydrates, mainly ettringite and stratlingite.
Construction and Building Materials, 2015
The scope of this paper is to study the sulphate attack on concrete with new testing methods base... more The scope of this paper is to study the sulphate attack on concrete with new testing methods based on vibrational spectroscopy with mechanical waves. These are based on Non-linear Impact Resonance Acoustic Spectroscopy (NIRAS) that allows detecting the frequency shift of its resonant modes. Both, signal quality factor and alpha, are measured to monitor the increase of the non-linearity of the material due to the stiffness change on the matrix after being attacked. Different Portland cement matrices were assessed and results between vibrational tests and the traditional expansion ASTM method were compared. Two types of cement with different C 3 A content were tested for external sulphate attack and one cement with high C 3 A content with different amount of addition of SO 3 on the original mix was tested for internal attack. NIRAS was suitable for monitoring external sulphate attack process. A microstructual analysis was carried out with thermogravimetry (TG), scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques in order to detect harmful products on damaged series.
Construction and Building Materials, 2015
This paper describes a study of the damage caused by corrosion to the reinforcement rebars of a 4... more This paper describes a study of the damage caused by corrosion to the reinforcement rebars of a 40year old building used as a car park at a distance of 20 metres from the sea. The corrosion levels of d by optical and electron microscopy. Carbonation depths and chloride contents (Vorhard method) of the concrete cover were measured in situ. EDX was used to analyze the condition of the reinforcement surfaces and the morphology and composition of the oxides. A high degree of corrosion was observed in all the above elements, carbonation had reached the depth of the reinforcement in all the samples studied, and the concrete chloride levels were far in excess of the recommended maximums. The study of the reinforcement rebars revealed different types of oxides of varying morphologies, compaction and colouring according to chloride content. A comparison with previous studies allowed us to verify the presence of crystals of at least akaganeite, lepidocrocite and goethite.
Journal of Sustainable Cement-Based Materials, 2012
The properties and microstructure of alkali-activated vitreous calcium aluminosilicate (VCAS) are... more The properties and microstructure of alkali-activated vitreous calcium aluminosilicate (VCAS) are presented in this paper. VCAS is manufactured from a by-product of the glass fibre industry and has been activated using NaOH and KOH solutions. The microstructure and mechanical properties of alkali-activated VCAS pastes and mortars are reported. The results show that depending on the type and concentration of hydroxide solution used, mortar samples with compressive strengths up to 77 MPa can be formed after curing for 3 days at 65ºC. The research demonstrates the potential of VCAS to produce alkali-activated cements and the importance of alkali type and concentration in optimising properties and microstructure.
Microscopy and Microanalysis, 2015
Agrowastes are produced worldwide in huge quantities and they contain interesting elements for pr... more Agrowastes are produced worldwide in huge quantities and they contain interesting elements for producing inorganic cementing binders, especially silicon. Conversion of agrowastes into ash is an interesting way of yielding raw material used in the manufacture of low-CO2binders. Silica-rich ashes are preferred for preparing inorganic binders. Sugarcane leaves (Saccharum officinarum, SL) and bamboo leaves (Bambusa vulgaris, BvL andBambusa gigantea, BgL), and their corresponding ashes (SLA, BvLA, and BgLA), were chosen as case studies. These samples were analyzed by means of optical microscopy, Cryo-scanning electron microscopy (SEM), SEM, and field emission scanning electron microscopy. Spodograms were obtained for BvLA and BgLA, which have high proportions of silicon, but no spodogram was obtained for SLA because of the low silicon content. Different types of phytoliths (specific cells, reservoirs of silica in plants) in the studied leaves were observed. These phytoliths maintained th...
Portland Cement based materials are susceptible to attack by sulfates greater or lesser extent de... more Portland Cement based materials are susceptible to attack by sulfates greater or lesser extent depending on tricalcium aluminate content in the chemical composition of the cement. The sulfate ion produces secondary ettringite from hydrated calcium aluminate and, also, calcium sulfate dihydrate with portlandite. Given the expansive nature of these products containing sulfate, the attack starts with an initial densification that results in internal microcracking until the material breaks just when the attack is severe. In this study we have chosen two types of cement with different tricalcium aluminate content to produce cement mortar with water to cement ratio of 0.6. These mortars are subjected to an external attack of sulfates when they are immersed in a solution of sodium sulfate with a concentration of 15% by weight. We assessed the evolution of sulfate attack by expansion measures and by testing the flexural resonance. We have obtained the natural frequencies of vibration and th...
ABSTRACT La ceniza volante se trata de un material inorgánico procedente de la combustión del car... more ABSTRACT La ceniza volante se trata de un material inorgánico procedente de la combustión del carbón en las centrales termoeléctricas. Este material presenta reactividad puzolánica, lo que permite reducir la cantidad de cemento en la fabricación de morteros y hormigones produciendo beneficios medioambientales, y mejora en las propiedades físicas, mecánicas y de durabilidad. En este estudio se evalúa los efectos de una ceniza volante en pastas y morteros de cemento Portland. Para ello se elaboran pastas y morteros de sólo cemento Portland y otras con sustitución de cemento por ceniza volante en un porcentaje de 40%, curados a temperatura ambiente. En pastas se realizan ensayos de termogravimetría y microscopía electrónica de barrido mientras que en morteros se evalúa la evolución de la resistencia mecánica y la frecuencia de resonancia a flexión con la edad de curado. Los resultados muestran la reactividad puzolánica de la ceniza volante, sobre todo a tiempos medios y largos de curado.
Construction and Building Materials, 2014
Porcelain stoneware tiles are produced in large quantities in Spain. The aim of this research was... more Porcelain stoneware tiles are produced in large quantities in Spain. The aim of this research was to investigate the influence of the alkali activator concentration and calcium dosage on the fresh behavior, compressive strength and microstructure of the binder produced by the alkali activation of porcelain stoneware waste. The results show that the activator concentration strongly influences the fresh behavior of mortars. The calcium to sodium molar ratio (M Ca) greatly influenced the hardening process so that the mortars mixed with a constant M Ca ratio exhibited similar setting times. Furthermore, when keeping the SiO 2 concentration constant, a linear evolution of compressive strength with sodium addition was observed. Mortar samples with up to 36 MPa under compression were obtained after curing for 7 days at 65°C.
Key Engineering Materials, 2014
Spent FCC catalyst is a waste from the petrochemical industry which has excellent pozzolanic prop... more Spent FCC catalyst is a waste from the petrochemical industry which has excellent pozzolanic properties, containing more than 90% silica and alumina. Its similarity to metakaolin creates interesting prospects for its use in the production of alkali-activated binders. In this study, the alkali activation of this residue, spent FCC catalyst, through mixtures with alkali hydroxide and silicate solutions (both sodium and potassium) has been carried out. The alkali cation had an important role in the nature of AA-FCC pastes: some differences in the mass loss in the thermogravimetric tests and in the X-ray mineral characterization were found. No significant differences in compressive strength were observed for mortars cured for 3 days in several conditions: room temperature and 65oC. Prepared AA-FCC mortars had a compressive strength of about 65-70 MPa. Microstructural studies showed that an amorphous, dense and compact microstructure was obtained, independent of the activating solution a...
Waste and Biomass Valorization, 2013
Ceramic materials represent around 45% of construction and demolition waste, and originate not on... more Ceramic materials represent around 45% of construction and demolition waste, and originate not only from the building process, but also as bricks and tiles rejected from the industry. Despite the fact that these wastes are mostly used as road sub-base or construction backfill materials, they can also be employed as supplementary cementitious materials, or even as raw material for alkali-activated binders. The aim of this research was to investigate the properties and microstructure of alkali-activated cement pastes and mortars produced from ceramic waste materials of various origins. Sodium hydroxide and sodium silicate were used to prepare the activating solution. The compressive strength of the developed mortars ranged between 22 and 41 MPa after 7 days of curing at 65ºC, depending on the sodium concentration in the solution and the water/binder ratio. These results demonstrate the possibility of using alkali-activated ceramic materials in building applications.
Materials Letters, 2012
This paper provides information about the synthesis and mechanical properties of geopolymers base... more This paper provides information about the synthesis and mechanical properties of geopolymers based on fluid catalytic cracking catalyst residue (FCC). FCC was alkali activated with solutions containing different SiO 2 /Na 2 O ratios. The microstructure and mechanical properties were analysed by using several instrumental techniques. FCC geopolymers are mechanically stable, yielding compressive strength about 68MPa when mortars are cured at 65ºC during three days. The results confirm the viability of producing geopolymers based on FCC.
Materials Letters, 2012
This paper evaluates the use of hydrated Portland cement as the raw material in the production of... more This paper evaluates the use of hydrated Portland cement as the raw material in the production of geopolymers. The silicon and aluminium oxides needed for the geopolymerization process were produced by the carbonation of hydrated Portland cement, which transforms CSH and CAH (Portland cement hydrates) into silica and alumina gels. Hydrated-carbonated Portland cement was alkali activated with a NaOH/waterglass solution. Pastes and mortars were prepared, and micro-structural and mechanical properties were analyzed. It has been noted that geopolymers are mechanically stable and yield compressive strength higher than 10MPa when mortars are cured at 65º C for three days. The results have shown that there are interesting possibilities for re-using the cement-rich fraction of construction and demolition waste. Alkaline activation of hydrated-carbonated Portland cement could be considered a low CO 2-emission binder.
Materials Letters, 2014
Geopolymers simultaneously containing two waste materials have been developed: Fluid catalytic cr... more Geopolymers simultaneously containing two waste materials have been developed: Fluid catalytic cracking catalyst (FCC), as mineral admixture and Rice Husk Ash (RHA) for preparing alkaline activator. Alkaline activators were prepared by refluxing aqueous mixtures of ground or original RHA with NaOH. All mortars with alkaline activator containing RHA showed compressive strength (cured at 65ºC for one day) in the range of 31-41 MPa, which was similar to control mortar prepared using an equivalent mixture of NaOH and water glass. Refluxing times between 30 and 240 minutes yielded good performance mortars. This new way of valorisation would imply economic and environmental benefits in geopolymer production.
Materials, 2013
Blast furnace slag (BFS)/sugar cane bagasse ash (SCBA) blends were assessed for the production of... more Blast furnace slag (BFS)/sugar cane bagasse ash (SCBA) blends were assessed for the production of alkali-activated pastes and mortars. SCBA was collected from a lagoon in which wastes from a sugar cane industry were poured. After previous dry and grinding processes, SCBA was chemically characterized: it had a large percentage of organic matter (ca. 25%). Solutions of sodium hydroxide and sodium silicate were used as activating reagents. Different BFS/SCBA mixtures were studied, replacing part of the BFS by SCBA from 0 to 40% by weight. The mechanical strength of mortar was measured, obtaining values about 60 MPa of compressive strength for BFS/SCBA systems after 270 days of curing at 20 °C. Also, microstructural properties were assessed by means of SEM, TGA, XRD, pH, electrical conductivity, FTIR spectroscopy and MIP. Results showed a good stability of matrices developed by means of alkali-activation. It was demonstrated that sugar cane bagasse ash is an interesting source for preparing alkali-activated binders.
Materiales de Construcción, 2009
Estudio del comportamiento de diversos residuos de catalizadores de craqueo catalítico (FCC) en c... more Estudio del comportamiento de diversos residuos de catalizadores de craqueo catalítico (FCC) en cemento Portland
Journal of Thermal Analysis and Calorimetry, 2010
In this paper the methodology to utilization of High Resolution Thermogravimetric (HRTG) software... more In this paper the methodology to utilization of High Resolution Thermogravimetric (HRTG) software for construction materials like Portland cement pastes is presented. The aim of this technique is to make easier the changes identification of the decomposition reactions that frequently are overlapping on conventional Thermogravimetric Analysis (TG). The optimum parameters about sample mass and purge flow gas were established. It is necessary to work with high quantity of sample and without purge gas was concluded in order to get better results and excellent reproducibility. The tests have average velocity higher to 3 °C.min-1 in the temperature range selected (35-300°C), it shows that the HRTG is not an expensive spent-time technique.
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Papers by Lourdes Gisell Puchoc Soriano