Open Access
Project risk management methodology for small firms
(Elsevier, 2014) Marcelino Sádaba, Sara; Pérez Ezcurdia, Amaya; Echeverría Lazcano, Amparo; Villanueva Roldán, Pedro; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería
Open Access
Technical and environmental characterization of hydraulic and alkaline binders
(Elsevier, 2018) Espuelas Zuazu, Sandra; Echeverria Lazcano, Angel María; Marcelino Sádaba, Sara; Prieto Cobo, Eduardo; Seco Meneses, Andrés; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak; Gobierno de Navarra / Nafarroako Gobernua, 0011-1365-2017-000176
Portland cement is a widely used binder in construction and building applications because of its good properties. Despite its convenience as construction material, the social demands and policies trends are requesting a lower impact and more sustainable cement manufacturing industry. The most effective ways to reach this goal are the substitution of clinker by different wastes or by-products in the cement composition or the development of more sustainable binders like the alkali activated binders. This work analyzes from a technical and environmental point of view the substitution of a clinker based CEM I common cement for the construction mortars manufacturing. Four common cements with different ground granulated blastfurnace slags (GGBS) or fly ashes (FA) contents as well as fifteen alkali activated binders (AAB) combinations were considered. Fresh consistency, density, compressive strength (CS) tests and life cycle analysis were carried out to state the ability of these different hydraulic and alkaline activated binders for the CEM I substitution. The results obtained demonstrated the technical and environmental convenience of these binders for the construction mortars manufacturing.
Open Access
Experimental study of the performance and emission characteristics of an adapted commercial four-cylinder spark ignition engine running on hydrogen-methane mixtures
(Elsevier, 2014) Diéguez Elizondo, Pedro; Urroz Unzueta, José Carlos; Marcelino Sádaba, Sara; Pérez Ezcurdia, Amaya; Benito Amurrio, Marta; Sáinz Casas, David; Gandía Pascual, Luis; Ingeniería; Ingeniaritza
The use of hydrogen/methane mixtures with low methane contents as fuels for internal combustion engines (ICEs) may help to speed up the development of the hydrogen energy market and contribute to the decarbonization of the transportation sector. In this work, a commercial 1.4 L four-cylinder Volkswagen spark-ignition engine previously adapted to operate on pure hydrogen has been fueled with hydrogen/methane mixtures with 5–20 vol.% methane (29.6–66.7 wt.%). An experimental program has been executed by varying the fuel composition, air-to-fuel ratio (λ), spark advance and engine speed. A discussion of the results regarding the engine performance (brake torque, brake mean effective pressure, thermal efficiency) and emissions (nitrogen oxides, CO and unburned hydrocarbons) is presented. The results reveal that λ is the most influential variable on the engine behavior due to its marked effect on the combustion temperature. As far as relatively high values of λ have to be used to prevent knock, the effect on the engine performance is negative. In contrast, the specific emissions of nitrogen oxides decrease due to a reduced formation of thermal NOx. A clear positive effect of reducing the spark advance on the specific NOx emissions has been observed as well. As concerns CO and unburned hydrocarbons (HCs), their specific emissions increase with the methane content of the fuel mixture, as expected. However, they also increase as λ increases in spite of the lower fuel concentration due to a proportionally higher reduction of the power. Finally, the effect of the increase of the engine speed is positive on the CO and HCs emissions but negative on that of NOx due to improved mixing and higher temperature associated to intensified turbulence in the cylinders.
Open Access
Sustainable unﬁred bricks manufacturing from construction and demolition wastes
(Elsevier, 2018) Seco Meneses, Andrés; Omer, Joshua; Marcelino Sádaba, Sara; Espuelas Zuazu, Sandra; Prieto Cobo, Eduardo; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak
The management of construction and demolition wastes is a huge challenge for most Governments. Thegreatest component of such wastes is concrete and masonry fragments or remains. Among the most com-mon approaches to valorization of such w astes is to convert them to recycled aggregates, however thismay be hampered by low quality of some recycled aggregates compared to natural aggregates. This paperpresents the results of experimental investigation where concrete and ceramic remains were used to par-tially substitute clay soil in producing unﬁred bricks. The bricks were then tested for mechanical strength,water absorption freeze-thaw resistance. Additionally the environmental impact of the bricks wasassessed based on Life Cycle Analysis (LCA). It was established that concrete waste could be used to sub-stitute up to 50% of the clay whereas ceramic wastes could only substitute a maximum of 30% of the clay.Blended bricks made from clay and concrete waste mixes had a lower mechanical strength than thosemade from clay and ceramic waste. As regards water absorption, there was no marked differencebetween the two blends of brick however reduction in water resistance was slightly greater in bricks con-taining concrete waste that in those containing ceramic wastes. Also, tests showed that freeze-thawresistance was greater in bricks blended with concrete wastes than in those incorporating ceramicwastes. Life Cycle analyses demonstrated that it is the binder content in the mix that largely determinesthe environmental impact of the blended bricks. Lastly, it was demonstrated that the most desirable tech-nical and environmental credentials of brick material mixes resulted from using the binder combination:CL-90-S+GGBS 2/8.
Open Access
Magnesium oxide as alternative binder for unﬁred clay bricks manufacturing
(Elsevier, 2017) Espuelas Zuazu, Sandra; Omer, Joshua; Marcelino Sádaba, Sara; Echeverria Lazcano, Angel María; Seco Meneses, Andrés; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Replacement of ﬁred bricks by unﬁred ones could be an eﬀective way to reduce the building industryenvironmental footprint: Their manufacture not only requires less energy and natural resources but alsogenerates less waste. Bricks are based on the use of an additive cementitious material in the form of a binder,usually lime or cement. Such additives have a great environmental impact owing to the high energy consumptionand CO2during in their manufacturing process. In this article experiments are carried out in order to investigatethe applicability of a MgO rich industry by-product as a binder for the production of unﬁred clay bricks. Fromthe experiments, the MgO was observed to show ability to enhance the mechanical properties of a clay brick inmuch the same way as lime does. Water absorption tests on bricks revealed the superiority of MgO over lime inenhancing the durability properties of unﬁred bricks. The laboratory results demonstrate the high potential ofMgO based additives as alternative binders to the calcium based ones. Consequently, this oﬀers opportunity forreducing the environmental impact associated with the use of ﬁred clay bricks. In addition, it could allow aneﬀective way for the valorization of MgO containing industry by-products that currently discarded to landﬁlls
Open Access
Sulfate soils stabilization with magnesium-based binders
(Elsevier, 2016) Seco Meneses, Andrés; Miqueléiz Jiménez, Luis; Prieto Cobo, Eduardo; Marcelino Sádaba, Sara; García, Beñat; Urmeneta, Pablo; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Sulfate soils' stabilization is a very interesting subject with technical, economic and environmental implications. The difficulty of their stabilization is due to the fact that the usual stabilizer additives are based on calcium. In these soils, sulfate combines with the calcium from the additive and the aluminum from the clay, resulting in a highly hydrated expansive mineral named ettringite. This provokes the swelling of the treated material and even its destruction. This study analyzes the result of the substitution of the calciumbased additives by one alternative additive based on magnesium, an industrial byproduct named PC-8, in the stabilization of five different sulfate soils. From a mechanical point of view soils treated with PC-8 reached similar resistance values to the lime treated ones, of about 2–3 MPa for 4% dosage and 2–5 MPa for 8% dosage, being usually better with the PC-8 results than with the lime ones. When PC-8 was combined with GGBS the resistance values increased up to 11–13 MPa and the lime-GGBS reached the 6–7 MPa. The natural swelling of the soils treated with PC-8 decreased substantially and maintained constant even for immersion at long-term. In the case of the soils treated with lime, long-termswelling increased up to very high values even in the case of soilswithout natural swelling. XRD analysis of these samples demonstrated the existence of ettringite in 4 of the 5 soilswhen theywere treated with lime and there was not expansive minerals in the PC-8 treated soils, agreeing with the swelling observed behavior of the soils when treated with both additives.
Open Access
Conversion of a gasoline engine-generator set to a bi-fuel (hydrogen/gasoline) electronic fuel-injected power unit
(Elsevier, 2011) Sáinz Casas, David; Diéguez Elizondo, Pedro; Urroz Unzueta, José Carlos; Sopena Serna, Carlos; Guelbenzu, E.; Pérez Ezcurdia, Amaya; Benito Amurrio, Marta; Marcelino Sádaba, Sara; Arzamendi Manterola, Gurutze; Gandía Pascual, Luis; Ingeniería; Ingeniaritza
The modifications performed to convert a gasoline carbureted engine-generator set to a bi-fuel (hydrogen/gasoline) electronic fuel-injected power unit are described. Main changes affected the gasoline and gas injectors, the injector seats on the existing inlet manifold, camshaft and crankshaft wheels with their corresponding Hall sensors, throttle position and oil temperature sensors as well as the electronic management unit. When working on gasoline, the engine-generator set was able to provide up to 8 kW of continuous electric power (10 kW peak power), whereas working on hydrogen it provided up to 5 kW of electric power at an engine speed of 3000 rpm. The air-to-fuel equivalence ratio (λ) was adjusted to stoichiometric (λ = 1) for gasoline. In contrast, when using hydrogen the engine worked ultra-lean (λ = 3) in the absence of connected electric load and richer as the load increased. Comparisons of the fuel consumptions and pollutant emissions running on gasoline and hydrogen were performed at the same engine speed and electric loads between 1 and 5 kW. The specific fuel consumption was much lower with the engine running on hydrogen than on gasoline. At 5 kW of load up to 26% of thermal efficiency was reached with hydrogen whereas only 20% was achieved with the engine running on gasoline. Regarding the NOx emissions, they were low, of the order of 30 ppm for loads below 4 kW for the engine-generator set working on hydrogen. The bi-fuel engine is very reliable and the required modifications can be performed without excessive difficulties thus allowing taking advantage of the well-established existing fabrication processes of internal combustion engines looking to speed up the implementation of the energetic uses of hydrogen.
Open Access
Challenges in Life Cycle Assessment (LCA) of stabilised clay-based construction materials
(Elsevier, 2017) Marcelino Sádaba, Sara; Kinuthia, John; Oti, Jonathan; Seco Meneses, Andrés; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak
The preference of clay-based materials for sustainable construction is well-established. The establishment ofsustainability credentials of emergent construction materials is very subjective, and most available tools are notfully equipped to deal with individual material systems, such as composite cement- or lime-based cementitioussystems, including clay-based blocks and bricks. The main problem emanates from the challenges of the audit ofeach aspect of the material processing, and especially the quantification of the most relevant inputs into thecomposite product. The variability in material ingredients, and lack of data for each aspect of the manufacturingprocesses involved creates major challenges. Incorporation of materials with long and complex recyclingprocesses further exacerbate the challenge. These incorporations create problems in terms of accurate materialtrails and data for input in a robust Life Cycle Assessment (LCA) of individual products. This paper reports on asimplified approach towards full LCA of seven clay-based brick products developed in UK (4) and Spain (3), based on known material data and estimated energy inputs in the manufacturing processes. The UK-based brickscomprise of Lower Oxford Clay (LOC), stabilised using combinations of hydrated lime, Ground Granulated Blast-furnace Slag (GGBS) and Portland cement (PC). In order to test the robustness of the proposed approach, resultson UK-based bricks are compared with a parallel LCA on clay-based product developed in Spain. Finally, theclay-based products are compared with a typical Portland cement-based concrete block andfired clay brick. Inthe LCA, boundary conditions includefixed transport, thus attempting to factor only the material ingredients,their known atmospheric emissions, and estimated energy inputs during processing. Results suggest that themost challenging aspect in the undertaking of LCA is the availability of reliable input data. Results also show thatthere are numerous parameters that can reliably and corroboratively facilitate the comparison of performance, besides carbon dioxide emissions.