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The granulometric distribution of the aggregates used in pervious concrete can significantly impact its mechanical and hydraulic properties by modifying granular skeleton and pore distribution. The unit weight increases when single-sized aggregates are combined, which results in improved mechanical properties. In this study, the maximum density methodology was applied to enhance pervious concrete’s mechanical strength by using three narrow-sized basaltic aggregates and their combination. The experimental results showed that the mechanical performance of the samples created with packed aggregates improved compressive strength by up to 81.2% and the energy support impact was higher than 225 J (50% higher than the reference sample) after curing for 28 days. Although the densification of packing aggregates increased, the greatest reduction in porosity was 24.3%. The lowest infiltration rate was 0.43 cm/s, a satisfactory value according to the literature. These findings suggest that the aggregates packing methodology is effective in producing optimized and sustainable pervious concretes.

Made available in DSpace on 2022-04-28T19:53:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-07-15 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) This study evaluated the compressive strength performance and microstructure of binary blast furnace slag-sewage sludge ash (BFS-SSA) alkali-activated mortars, in which rice husk ash (RHA) was dissolved in NaOH solution to replace commercial sodium silicate. The dissolution of RHA, performed in a thermal bottle with NaOH solution, enhanced the compressive strength of the alkali-activated mortars based on BFS up to 4.5-fold. BFS-SSA based mortars (10–40% SSA), activated with NaOH/RHA-based sodium silicate suspensions, reached a compressive strength up to 30 MPa after 28 curing days at 20°C. The RHA dissolution enhanced the strength and sustainability of the BFS-SSA alkali-activated mortars. Universidade Estadual Paulista (UNESP) Faculdade de Engenharia de Ilha Solteira MAC – Grupo de Pesquisa em Materiais Alternativos de Construção, SP ICITECH – Instituto de Ciencia y Tecnología del Hormigón Universitat Politècnica de València (UPV) Universidade Estadual Paulista (UNESP) Faculdade de Engenharia de Ilha Solteira MAC – Grupo de Pesquisa em Materiais Alternativos de Construção, SP

[EN] This work studies the possibility of using geopolymer materials to enhance the mechanical and durability properties of hydrated lime¿pozzolan mixtures, which gave rise to the so-called ¿hybrid systems¿. Two different waste types were used as pozzolan in the lime¿pozzolan system: rice husk ash (RHA) and spent fluid catalytic cracking (FCC). The geopolymer fabricated with FCC was activated with commercial reagents (NaOH and Na2SiO3), and also with alternative sources of silica to obtain a lower carbon footprint in these mixtures. The alternative silica sources were RHA and residual diatomaceous earth (RDE) from the beer industry. The geopolymer mixture substituted the lime¿pozzolan mixture for 30% replacement in weight. The hybrid systems showed better mechanical strengths for the short and medium curing ages in relation to the lime¿pozzolan mixtures. Thermogravimetric analyses were performed to characterise the types of products formed in these mixtures. In the durability studies, hybrid systems better performed in freeze¿thaw cycles and obtained lower capillarity water absorption values., This research forms part of a project supported by MINECO and FEDER funds (ECOSOST RTI2018-097612-B-C21-AR).

[EN] In the last decade, herbaceous and agricultural biomass have been used as an alternative energy source. As consequence, large amounts of residual ashes containing potassium (potassium-rich ashes) have been generated. Olive biomass ash (OBA) and almond shell ash (ABA) have been successfully used as alkali source in the alkaline activation of ground granulated blast furnace slag (BFS). This study focuses on the production of new and alternative alkaline activators for BFS systems using nutshell ashes (NBA), mango seed-bark ashes (MBA) and hazelnut shell ashes (HBA). The chemical and mineralogical composition of these ashes were assessed and, the mechanical and microstructural properties of BFS pastes activated with NBA, MBA and HBA were evaluated. The results indicated that all assessed materials are potassium-rich ashes differing mainly on the amount of CaO and P2O5. The compressive strength of BFS pastes yielded about 26 MPa and, according to FESEM/EDS analysis, K2O (in the range 8.03¿24.33%) replaces chemical bounded Ca+2, forming C-(K)-A-S-H gel., We thank the Spanish Government MINECO and FEDER for funding the ECOSOST RTI-2018-097612-B-C21 Project.

Los cementos de activación alcalina (CAA) requieren de un componente alcalino para la activación del precursor. La fabricación del activador alcalino (AA) supone un consumo energético y de materias primas muy importante, de modo que la huella de carbono de los CAA está fundamentalmente influenciada por ese factor. Una alternativa es el uso de otras materias para la preparación del AA. En este trabajo se realiza un exhaustivo análisis de las diferentes alternativas: materias de base silícea para la preparación de silicatos alternativos y materias de base alcalina. Se comparan de forma relativa las huellas de carbono con respecto a cementos Portland comerciales, y se analiza el efecto que tiene la sustitución de reactivos comerciales por activadores alternativos.

The aim of this study was to use the electrical impedance spectroscopy technique (IS) to carry out a systematic study on the mechanism of metakaolin geopolymerization for up to 7 curing days. The study was developed on two batches of metakaolin (MK), and their reaction processes were compared. Interpretative fundamental elements were developed based on the effective electrical conductivity curves regarding the metakaolin geopolymerization. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were previously carried out and used to interpret and validate the electrical behavior of the fresh and hardened MK-based geopolymer pastes. The results highlighted the sensibility of the impedance technique to the identification and description of the MK geopolymerization process, as well as the changes resulting from even slight variations in the metakaolin composition. Furthermore, this indicated that the geopolymerization process in highly alkaline solutions could be divided into seven stages, including the processes of dissolution, nucleation, precipitation and formation of the gel and, eventually, the retraction/microcracks constitution. Late dissolution processes could be observed during the more advanced stages and were attributed to particles not being fully hydrated.

[EN] Cellular concrete is an alternative to conventional concrete as a low-density and high-insulating building material. The eco-cellular concretes (ECCs) based on geopolymer technology have been recently introduced by the scientific community. A form of ECC was studied, in which the fluid catalytic cracking residue and the blast furnace slag were employed as precursors, the rice husk ash was utilized as an alternative silica source in the activator, and the aerating reagent was replaced with recycled aluminum foil. Field emission scanning electron microscopy, optical microscopy, and ImageJ version 1.48 software (National Institutes of Health) were employed to characterize the void distribution. Bulk density and porosity were determined by hydric tests. The results revealed that lowest densities without strength loss were obtained when the cementing matrix had a homogeneous void system: similar spacing between pores, narrow size ranges, and nonconnected pores. A relationship was established between open and closed porosity with density and thermal conductivity., The authors acknowledge the financial support from the Universitat Politecnica de Valencia (UPV) through internal project GEOCELPLUS. The authors are especially grateful to Dr. Josefa L. Rosello Caselles for the recycled aluminum foil, and also to the Electronic Microscopy Service of the UPV. Thanks also go to DACSA, BP Oil, and Cementval for supplying the raw materials.

Resource recovery from waste is one of the most important ways to implement the so-called circular economy, and the use of alkali activated materials can become an alternative for traditional PC-based materials. These types of materials are based on waste resources involving a lower carbon footprint and present similar or high properties and good durability compared to that Portland cement (PC). This research work proposes using new waste generated in different types of industries. Four waste types were employed: fluid catalytic cracking residue (FCC) from the petrochemical industry, ceramic sanitary ware (CSW) from the construction industry, rice husk ash (RHA), diatomaceous waste from beer filtration (DB) (food industry). FCC and CSW were employed as precursor materials, and mixtures of both showed good properties of the obtained alkali activated materials generated with commercial products as activators (NaOH/waterglass). RHA and DB were herein used as an alternative silica source to prepare the alkaline activating solution. Mechanical behavior was studied by the compressive strength development of mortars. The corresponding pastes were characterized by X-ray diffraction, thermogravimetric analysis, and microscopy studies. The results were satisfactory, and demonstrated that employing these alternative activators from waste produces alkali activated materials with good mechanical properties, which were sometimes similar or even better than those obtained with commercial reagents.

[EN] The objective of this study was to evaluate the effects of potassium extraction on the pozzolanicity of sugar cane bagasse ash (SCBA), with the aim of producing reactive ash for use in cementitious composites. The sugar cane bagasse ashes were produced at 600 °C for 60 min, with a heating rate of 4 °C/min. The ashes were then ground and washed for potassium extraction. In order to assess the ash behaviour before and after potassium extraction, the following procedures were performed: energy-dispersive spectroscopy (EDS), loss on ignition (LOI), particle size distribution, x-ray powder diffraction (XRD), x-ray diffraction in calcium hydroxide paste, analysis of lime fixation by thermogravimetry, and evaluation of pozzolanic reactivity analyses. Results show that the extraction of potassium, increases the concentration of silica causing a greater pozzolanic reactivity of the ashes., This study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Brasil (CAPES) - Finance Code 001.

[EN] Studies on reactivity of sugarcane bagasse ash (SCBA), obtained by an autogenous combustion process, with low loss on ignition and three different particle sizes were carried out (SCBA-1, SCBA-2 and SCBA-3). The ashes were characterized by their particle size distribution, chemical composition, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM). The ash with lowest particle size was SCBA-3, followed by SCBA-2, which both were finer than SCBA-1. Calcium hydroxide/SCBA blends were assessed by means of loss of electrical conductivity (Lc), TGA and FESEM. Portland cement/SCBA pastes were analyzed through isothermal calorimetry, TGA, FESEM and compressive strength. Results showed that SCBA with lowest particle size (SCBA-3) presented highest reactivity, which resulted in statically significant better compressive strength than that of control paste (with only Portland cement) after 28 days of curing. The improvement on compressive strength by employing SCBA-3 respect to control and SCBA-1 were 17.9 and 14.1%, respectively, after 180 days of curing., This study was financed in part by the Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ).

[EN] This paper aimed to evaluate the long-term compressive strength development of the sewage sludge ash/metakaolin (SSA/MK)¿based geopolymer. SSA/MK¿based geopolymeric mortars and pastes were produced at 25ºC with different SSA contents (0 - 30 wt.%). Compressive strength tests were run within the 3-720 curing days range. A physicochemical characterisation (X-ray diffraction and scanning electron microscopy) was performed in geopolymeric pastes. All the geopolymeric mortars presented a compressive strength gain with curing time. The mortars with all the SSA evaluated contents (10, 20, 30 wt.%) developed a compressive strength over 40 MPa after 720 curing days at 25ºC. The maximum compressive strength of the mortars with SSA was approximately 61 MPa (10 wt.% of SSA), similarly to the reference mortar (100% MK-based geopolymer). The microstructure analyses showed that the SSA/MK¿based geopolymer presented a dense microstructure with N-A-S-H gel formation., This study was financed partly by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Su-perior -Brasil (CAPES) -(Finance Code 001 and CAPES/DGU n. 266/12), and the National Council of Scientific and Technological Development -Bra-sil (CNPq) -(n. 14/2013, process 478057/2013-0 and 309015/2015-4). The authors would like to thank Programa Institucional de Internacionalizacao - CAPES -PrInt. The authors acknowledge the Scanning Electron Microscopy Service of FEIS/UN-ESP, Servico Municipal Autonomo de Agua e Es-goto (SEMAE) from the Sao Jose do Rio Preto city -SP, Brazil and Diatom Mineracao Ltda. The authors would like to thank Programa Institucional de Internacionalizacao CAPES -PrInt.

Spent fluid catalytic cracking (FCC) is produced worldwide and has homogeneous chemical, mineralogical, and physical properties, regardless of the petrol refinery source. This good performance facilitates its reuse, especially for making different types of cement or concrete. Spent FCC shows excellent reactivity in pozzolanic behavior terms because of high reactive silica and alumina contents. It has been demonstrated that milling waste represents appropriate conditioning for yielding the highest reactivity, but from the rheological point of view, replacement of Portland cement with spent FCC worsens the workability of the mixes. Spent FCC contains a significant amount of nickel and vanadium, but these heavy metals are strongly bonded to the structure and are not leached when specimens are tested under acidic conditions. The use of this waste has been described in different constructions. In all cases, the performance of the designed materials is very good, so it could be implemented as a new addition to the construction materials industry.

This paper evaluated the pozzolanic activity of ceramic sanitary ware (CSW) waste when blended with Portland cement (PC). CSW waste units were broken, crushed and milled to reduce their particle size. These particles were characterized by scanning electron microscopy (SEM-EDX), laser granulometry, X-ray fluorescence (XRF) and X-ray diffraction tests (XRD), and were then used to replace 0–50wt.% PC CEM I 42.5R in pastes and mortars. Workability of the fresh mortars was assessed by the flow-table spread test, and the mechanical properties and microstructure (thermogravimetry, SEM-EDX, XRD and Fourier transform infrared spectroscopy tests) were investigated in samples cured at 20°C for up to 365 days. No significant workability variations were observed with increasing waste contents and, although pozzolanic activity of CSW was relatively slow, it improved with the curing time, and mortars prepared with up to 25wt.% ceramic waste satisfied the requirements established for other pozzolanic materials, such as fly ash. En este artículo se evaluó la actividad puzolánica de residuos de cerámica sanitaria (CSW) en mezclas con cemento Portland (PC). Para reducir su tamaño de partícula se rompieron, trituraron y molieron piezas residuales de cerámica sanitaria. Las partículas resultantes fueron caracterizadas mediante microscopía electrónica de barrido (SEM-EDX), granulometría láser, fluorescencia de rayos X (XRF) y difracción de rayos X (XRD), utilizándose posteriormente para reemplazar entre un 0 y un 50% de cemento CEM I 42.5R en pastas y morteros. La trabajabilidad de los morteros frescos se evaluó mediante el método de la mesa de sacudidas, y las propiedades mecánicas y microestructura (análisis termogravimétricos, SEM-EDX, XRD y espectroscopía infrarroja por transformada de Fourier) se investigaron en muestras curadas a 20°C hasta 365 días. No se observaron variaciones significativas en la trabajabilidad al incrementar el contenido de residuo cerámico y, aunque la actividad puzolánica de la CSW fue relativamente lenta, mejoró con el tiempo de curado. Así, los morteros desarrollados con hasta un 25% en peso del residuo cerámico cumplieron con los requisitos normativos establecidos para otros materiales puzolánicos, como las cenizas volantes. The authors are grateful to the Spanish Ministry of Science, Innovation and Universities for supporting this research through Project ECOSOST RTI-2018-097612-B-C21, and to FEDER funding. They also thank the Institute for Science and Technology of Concrete (ICITECH) and Universitat Jaume I for providing the means to perform this study. Thanks are extended to the Scientific Instrumentation Centre of the Universitat Jaume I and the Electron Microscopy Service of the Universitat Politècnica de València for their help with the microstructural characterization analyses.

[EN] The microstructural features of heterogeneous and porous materials give rise to unique non-linear dynamic behaviour. The purpose of this work is to investigate the dynamic response of thermally damaged concrete specimens measured by two different techniques: Non-linear Impact Resonance Acoustic Spectroscopy (NIRAS) and new Flipped Accumulative Non-linear Single Impact Acoustic Spectroscopy (FANSIRAS). Specimens were characterised in two different dynamic condition states of the material: relaxed and conditioned. The specimen¿s relaxed state indicates that no previous dynamic excitation event ocurred. The conditioned state denotes that the specimen has been dynamically tested before. The NIRAS results show that the non-linear material parameters, af and aQ , are affected by their previous dynamic history (its conditioning). The recently proposed algorithm, FANSIRAS, extracts from a single resonant signal equivalent results to NIRAS when the specimen is conditioned. In this situation, both parameters af and aQ were equivalent. The results suggest that new NDT parameters based on non-linear hysteretic parameters can quantify the damage level of thermally treated mortar specimens., This work has been supported by the Spanish Administration under grants BIA2014-55311-C2, BIA2017-87573-C2, BES2015-071469, PAID-10-19 and FEDER funds.

Large amounts of waste are derived not only from construction processes, but also the demolition of existing buildings. Such waste occupies large volumes in landfills, which makes its final disposal difficult and expensive. Reusing this waste type is generally limited to being employed as filler material or recycled aggregate in concrete, which limits its valorisation. The present work proposes reusing construction and demolition waste to manufacture alkali-activated cement to improve its sustainability and recovery. Construction and demolition waste (C&DW) from a demolition waste collection plant in Valencia (Spain) was physically and chemically characterised. This residue contained large fractions of concrete, mortar, bricks, and other ceramic materials. X-ray fluorescence (XRF) analysis showed that its chemical composition was mainly CaO, SiO2 and Al2O3. X-ray diffraction (XRD) analysis revealed that it presented some crystalline products, and quartz (SiO2) and calcite (CaCO3) were the main components. Blends of C&DW and blast furnace slag (BFS) were alkali-activated with mixtures of sodium hydroxide and sodium silicate. The corresponding pastes were characterised by techniques such as thermogravimetry and scanning electron microscopy (SEM). The alkali-activated mortars were prepared, and the resulting mortars’ compressive strength was determined, which was as high as 58 MPa with the 50% C&DW-50% BFS mixture. This work concluded that it is possible to make new sustainable binders by the alkali activation of C&DW-BFS without using Portland cement.

Glass fiber reinforced cement (GRC) is an excellent composite for architects and engineers because it can be molded to produce laminar panels or to create complicated designs. GRC is a fine concrete reinforced with alkali-resistant glass fibers at 3–5% per mass. However, fiber durability is limited because of the aggressiveness of the alkaline medium produced during Portland cement hydration (effect of portlandite). The objective of this study is to assess GRC with high Portland cement replacement with pozzolans (ground fly ash or a mixture of ground fly ash and sonicated silica fume) in order to reduce the corrosion of the fibers. The selected high-content pozzolan (60% replacement) composites were tested under different conditions: aging, drying–wetting, freezing–thawing, and chemical attack (ammonium chloride and sulfuric acid). The modulus of rupture and toughness were determined. Composite behavior showed that the samples with pozzolans not only better resisted aging, but also physical and chemical attacks, and specimens presented a better modulus of rupture and toughness than the samples prepared with 100% Portland cement (control specimens). Due to the good behavior in durability terms, the high pozzolan content GRC products are suitable in potential corrosive environments for sunscreens, drainage channels, cable trays, sound barriers, or pavements.

[EN] Worldwide cement production is around 4.2 billion tons, and the fabrication of one ton of ordinary Portland cement emits around 900 kg of CO2. Blast furnace slag (BFS) is a byproduct used to produce alkali-activated materials (AAM). BFS production was estimated at about 350 million tons in 2018, and the BFS reuse rate in construction materials of developing countries is low. AAM can reduce CO2 emissions in relation to Portland cement materials: Its use in construction would be a golden opportunity for developing countries in forthcoming decades. The present research aims to formulate AAM destined for future applications in developing countries. Two activators were used: NaOH, Na2CO3, and a mixture of both. The results showed that compressive strengths within the 42¿56 MPa range after 28 curing days were obtained for the Na2CO3-activated mortars. The characterization analysis confirmed the presence of hydrotalcite, carbonated phases, CSH and CASH. The economic study showed that Na2CO3 was the cheapest activator in terms of the relative cost per ton and MPa of manufactured mortars. Finally, the environmental benefits of mortars based on this reagent were evidenced, and, in terms of kgCO2 emissions per ton and MPa, the mortars with Na2CO3 yielded 50% lower values than with NaOH., We would also like to thank the Spanish Government MINECO/FEDER (ECOSOST project RTI-2018-097612-B-C21) for supporting this research.

[EN] Soil stabilization using cementing materials is a well-known procedure for earth-based building blocks preparation. For the selected binding materials, innovation usually focuses on low carbon systems, many of which are based on alkaline activation. In the present paper, blast furnace slag (BFS) is used as a mineral precursor, and the innovative alkali activator was olive stone biomass ash (OBA). This means that the most important component in CO2 emissions terms, which is the alkali activator, has been replaced with a greener alternative: OBA. The OBA/BFS mixture was used to prepare compacted dolomitic soil blocks. These specimens were mechanically characterized by compression, and water strength coefficient and water absorption were assessed. The microstructure of blocks and the formation of cementing hydrates were analyzed by field emission scanning electron microscopy and thermogravimetry, respectively. The final compressive strength of the 120-day cured blocks was 27.8 MPa. It was concluded that OBA is a sustainable alkali activator alternative for producing BFS-stabilized soil-compacted blocks: CO2 emissions were 3.3 kgCO(2)/ton of stabilized soil, which is 96% less than that for ordinary Portland cement (OPC) stabilization., This research was funded by the Spanish Government and FEDER funds (MINECO/FEDER-Project RTI2018-09612-B-C21).

[EN] This paper focuses on investigating greener alternatives of cellular concrete technology to fulfil current searches for a shift to circular economy. A novel one-part eco-cellular concrete (ECC-OP) was developed and studied. The one-part alkali activated materials (AAM-OP) and new alkali-activated cellular concrete (AACC) technologies were combined to develop greener alternative of cellular concrete production. The progressive steps from traditional cellular concrete (TCC) based on ordinary Portland cement (OPC) and commercial aluminium powder (A) to a 100% waste-based cellular concrete are presented. Blast furnace slag (BFS) was the precursor, RHA was employed as the silica source, olive stone biomass ash (OBA) was the alkali source and recycled aluminium foil (AR) was employed as an aerating agent. The functional features of the materials were studied and compared to those established by the European standard and the American Concrete Institute (ACI) Committee 523 guides. The new ECC-OP with a bulk density, compressive strength and thermal conductivity that respectively equal 660 kg/m(3), 6.3 MPa and 0.20 W/ mK was obtained. Finally, a cradle-to-gate life cycle assessment (LCA) was made, where the industrial process of a masonry unit manufacture was raised by using each studied material. A 96% reduction in the kgCO(2)eq per m(3) of material was reached with the new proposed ECC-OP compared to TCC manufacturing. (C) 2020 Elsevier Ltd. All rights reserved., The authors gratefully acknowledge the GeocelPlus-UPV Project, Almazara Candela - Elche, Spain and DACSA S.A. - Tabernes Blanques, Spain and Cementval - Puerto de Sagunto, Spain.

[EN] Alkali-activated cements are widely studied as alternative and sustainable binder in soil stabilization. In this research work, a mold was designed and constructed, which allowed small cubic specimens to be made (40 x 40 x 40 mm(3)). With the newly designed mold, cubic samples of soil stabilized with portland cement (OPC) and alternative AAC (based on spent fluid catalytic cracking catalyst FCC) were prepared from which compressive strength was obtained. Cylindrical specimens were also prepared using the same binders as in the previous case to obtain their compressive strength. The results obtained in both cases were compared. Greater resistances for cubic samples were achieved. The cubic specimens were selected for being better in terms of standard deviation of compressive strength for AAC stabilized soil. The obtained compressive strength and standard deviation results were compared between the soil specimens stabilized with different stabilizers cured at 7, 14, 28, and 90 days. The method allows small-sized cubic specimens to be prepared. It improves ergonomics. It also facilitates a large number of specimens being obtained with a small amount of sample. Soil stabilized with AAC yielded higher compressive strength after 90 days compared to that with OPC., Spanish Ministry of Economy and Competitiveness, Grant/Award Number: BIA2015 70107-R.

[EN] Changes caused in the porous microstructure of ordinary Portland cement (OPC) mortars were studied using electrical impedance spectroscopy (EIS) and equivalent circuit (EqC). Two successive processes, at 20 ºC and 50 °C, consisting of several drying-rewetting cycles, were applied to the mortars. After each cycle, the electrical impedance and the amount of water absorbed were measured. The EIS-EqC methodology allowed to find two distributed impedance relaxations, associated to capillary and gel-C-S-H porosities, respectively. At room temperature any microstructural change was not detected. Nevertheless, at 50 °C two microstructural changes were inferred: 1) the volume of accessible porosity increased (pore coarsening) and 2) the surface of the conductive path through C-S-H gel became more conductive (surface smoothing)., The authors would like to thank the Spanish Ministry of Science and Innovation for supporting this research through the project BIA 2011-26947.

[EN] The use of almond-shell biomass ash (ABA) as an alternative component to the commercial reagents used in the activation of blast furnace slag (BFS) systems is investigated. The presence in its chemical composition of a high content of K2O indicate s that it can alkalinize the medium. 100% waste-based mixtures ABA/BFS were studied by micro- and macrostructural tests. A compressive strength of 44 MPa was achieved by the mortar with 25% ABA addition cured for 7 days at 65 °C. The microstructural analysis showed the formation of slightly different C(K)-A-S-H gels to those formed when using KOH. The use of ABA in BFS mortars is shown as a greener alternative for onstruction materials because the replace- ment of synthetic chemical reagents that produced around a 75¿80% of reduction in the values of kgCO2eq/m3 material, We wish to thank the Spanish Government for project support (MINECO/FEDER-Project RTI2018-09612-B-C21). The authors would like to thank Borges Agricultural & Industrial Nuts for supplying the biomass ash and the Electronic Microscopy Service at the UPV.

Made available in DSpace on 2018-12-11T16:47:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-09-15 This study presents the use of olive-stone biomass ash (OBA) as an alkali source in alkali-activated materials (AAM) based on blast furnace slag (BFS). The OBA was physically and chemically characterized. It presented high K2O and CaO contents, and yielded high alkalinity in water medium. The newly designed OBA + BFS mixes (a 100% waste-based AAM) reached a compressive strength of 30 MPa after 7 days of curing at 65 °C, which was higher than for BFS activated with KOH solution. Thermogravimetric studies showed the formation of C-S-H/(C,K)-A-S-H gels and hydrotalcite. The OBA presented excellent performance as a component in AAM and a good valorisation was achieved. ICITECH – GIQUIMA Instituto de Ciencia y Tecnología del Hormigón Universitat Politècnica de Valencia UNESP – Grupo de Pesquisa MAC – Materiais Alternativos de Construção Universidade Estadual Paulista (UNESP) Faculdade de Engenharia, Ilha Solteira UNESP – Grupo de Pesquisa MAC – Materiais Alternativos de Construção Universidade Estadual Paulista (UNESP) Faculdade de Engenharia, Ilha Solteira

[EN] In the context of world concern with the environment, this study aims to characterize an auto combustion produced bamboo leaf ash (BLA) by its pozzolanic behaviour, reactivity and its influence in the total porosity, pore size distribution, tortuosity and mechanical behaviour of cementitious matrices. The chemical and physical characterization of the BLA was carried using X-ray fluorescence, determination of amorphous silica content, X-ray diffraction, Fourier Transform Infrared Spectrophotometry (FTIR), laser granulometry and field emission scanning electron microscopy (FESEM). The assessed BLA is a siliceous material (74.23%) with an amorphous nature due to the amorphous silica content, which represents 92.33% of the total silica. The BLA was classified as highly reactive by assessing its pH and conductivity in a saturated calcium hydroxide (CH) medium for different proportions and temperatures. Frattini analysis, the study of CH:BLA pastes (Thermogravimetric analysis and FTIR) and Portland cement (OPC)/pozzolan pastes (Thermogravimetric analysis and FESEM) are in agreement with this classification. The replacement of OPC by BLA improved the mechanical behaviour of the cementitious matrices, as well their durability. All the mortars containing BLA presented very similar compressive strength to a control mortar (100% OPC) after only 3 days of curing and at the following tested curing ages: 7, 28 and 90 days. In the mercury intrusion porosimetry analysis, the pastes with 20 and 30% BLA content presented higher tortuosity or fewer connected pores than the control paste. Thus, the auto-combustion method proved to be successful and BLA is a suitable alternative for sustainable high-performance matrices. (C) 2019 Elsevier Ltd. All rights reserved., The authors would like to thank São Paulo Research Foundation (FAPESP), grant #2016/16403-5 and #2017/21563-4.

The necessity of cleaning wastewater because of environmental concerns produces a huge amount of sewage sludge (SS). The calcination of SS removes organic matter and reduces 90% of the original volume. The remaining material of inorganic nature is referred to as SS ash (SSA). SSA is a powdered material that contains high percentages of SiO2, Al2O3, Fe2O3, CaO, P2O5 and SO3, and has shown moderate reactivity in terms of pozzolanicity. This behaviour makes it viable as a cement replacement material in mortar and concrete, or in new alkali-activated binders. This approach will assist in achieving zero waste in relation to urban wastewater. Several aspects must be taken into account in this valorisation context: the origin of the wastewater and chemical and mineralogical nature of the SSA, calcination process, treatment of the ash and the dosage in mortar of concrete (SSA acting as filler or pozzolan), among others.

[EN] This paper explored the effect of sewage sludge ash (SSA) on the mechanical and microstructural properties of geopolymers based on metakaolin (MK) involving two different SiO2/Na2O molar ratios (0.8 and 1.6), two temperature curing conditions (25 degrees C and 65 degrees C) and various ages of curing (1, 3, 7, 14, 28, 90 or 180 days). The geopolymers were characterized using different techniques as X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and compressive strength of mortars. The compressive strength tests showed that the replacement of MK by SSA in 10 wt% when cured at 25 degrees C with the highest SiO2/Na2O molar ratio reaches similar compressive strengths after 14 days of curing compared to the samples with only MK, which reached a maximum compressive strength of 50.8 MPa at 180 days. The FTIR analyses carried out in the geopolymer pastes with SSA (10 wt% of SSA and 90 wt% of MK) showed a formation of N-A-S-H gels in the samples cured at 25 degrees C. The microstructural studies by XRD, TGA and SEM pointed out the formation of a crystalline phase as Na P-type zeolite in MK/SSA based-geopolymer pastes cured at 65 degrees C, which explained the loss of compressive strength of the samples cured at high temperature. However, the SSA retarded the crystallization process in the MK based-geopolymer. (C) 2019 Elsevier Ltd. All rights reserved., This research has been supported by funding agency Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (processo n° 309015/2015-4).