Showing papers by "Jordi Payá published in 2018"

Mineralogical evolution of cement pastes at early ages based on thermogravimetric analysis (TG)

Abstract: Ordinary thermogravimetric analysis (TG) and high-resolution TG tests were carried out on three different Portland cement pastes to study the phases present during the first day of hydration. Tests were run at 1, 6, 12 and 24 h of hydration, in order to determine the phases at these ages. High-resolution TG tests were used to separate decompositions presented in the 100–200 °C interval. The non-evaporable water determined by TG was used to determine hydration degree for the different ages. The effect of particle size distribution (PSD) on mineralogical evolution was established, as well as the addition of calcite as mineralogical filler. Finer PSD and calcite addition accelerate the hydration process, increasing the hydration degree on the first day of reaction between water and cement. According to high-resolution TG results, it was demonstrated that ettringite was the only decomposed phase in the 100–200 °C interval during the first 6 h of hydration for all studied cements. C-S-H phase starts to appear in all cements after 12 h of hydration.

Influence of calcium additions on the compressive strength and microstructure of alkali‐activated ceramic sanitary‐ware

Abstract: This is the peer reviewed version of the following article: Reig, L., Soriano Martinez, Lourdes, Tashima, M.M., Borrachero Rosado, Maria Victoria, Monzo Balbuena, Jose Ma, Paya Bernabeu, Jorge Juan. (2018). Influence of calcium additiions on the compressive strength and microstructure of alkali-activated ceramic sanitaryware.Journal of the American Ceramic Society, 101, null, 3094-3104. DOI: 10.1111/jace.15436 , which has been published in final form at http://doi.org/10.1111/jace.15436. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

Valorisation of sugarcane bagasse ash (SCBA) with high quartz content as pozzolanic material in Portland cement mixtures

Abstract: The authors would like to thank the Ministerio de Educacion, Cultura y Deporte of Spain (Cooperacion Interuniversitaria Program with Brazil, Project PHB-2011-0016-PC), CAPES-Brazil (Project CAPES/DGU No. 266/12), CNPq (Project 401724/2013-1) and Electron Microscopy Service of the Universitat Politecnica de Valencia.

Effect of Pyrogenic Silica and Nanosilica on Portland Cement Matrices

Abstract: In this work, the effect of pyrogenic silica and nanosilica on the properties of portland cement matrices is compared. Two chemically and mineralogically similar mineral additions (amorphou...

Influence of Addition of Fluid Catalytic Cracking Residue (FCC) and the SiO2 Concentration in Alkali-Activated Ceramic Sanitary-Ware (CSW) Binders

Abstract: Production of Portland cement requires a large volume of natural raw materials and releases huge amounts of CO2 to the atmosphere. Lower environmental impact alternatives focus on alkali-activated cements. In this paper, fluid catalytic cracking residue (FCC) was used to partially replace (0 wt %–50 wt %) ceramic sanitaryware (CSW) in alkali-activated systems. Samples were activated with NaOH and sodium silicate solutions and were cured at 65 °C for 7 days and at 20 °C for 28 and 90 days. In order to increase CSW/FCC binders’ sustainability, the influence of reducing the silica concentration (from 7.28 mol·kg−1 up to 2.91 mol·kg−1) was analyzed. The microstructure of the developed binders was investigated in pastes by X-ray diffraction, thermo tests and field emission scanning electron microscopy analyses. Compressive strength evolution was assessed in mortars. The results showed a synergetic effect of the CSW/FCC combinations so that, under the studied conditions, mechanical properties significantly improved when combining both waste materials (up to 70 MPa were achieved in the mortars containing 50 wt % FCC cured at room temperature for 90 days). Addition of FCC allowed CSW to be activated at room temperature, which significantly broadens the field of applications of alkali-activated CSW binders.

An Approach to a New Supplementary Cementing Material: Arundo donax Straw Ash

Abstract: Arundo donax is a plant native to Asia and is considered an invader species in the Mediterranean region and many tropical zones in the world. These invader plants can be collected to produce a biomass, which can be converted to ash by combustion. The scope of the study is to assess the use of these ashes (Arundo donax straw ash [ADSA]) as supplementary cementing material due to their relatively high silica content. Electron microscopy studies on dried and calcined samples of different plant parts (cane, sheath leaf and leaf) were carried out. Some different cellular structures were identified in the spodogram (remaining skeleton after calcination). Major silica content was found in leaves and sheath leaves. The main element in all the ashes studied, together with oxygen, was potassium (22 to 46% depending on the part of the plant). Chloride content was also high (5–13%), which limits their use to non-steel reinforced concrete. The pozzolanic reactivity of ADSA was assessed in pastes by thermogravimetric analysis and in mortars with ordinary Portland cement based on compressive strength development. Excellent results were found in terms of reactivity.

Optimum Use of Sugar Cane Straw Ash in Alkali-Activated Binders Based on Blast Furnace Slag

Abstract: Alkali-activated binders (AABs) are a material obtained from the combination of a solid precursor and an alkaline activating solution. In this study, one solid precursor used was blast-furn...

The Compressive Strength and Microstructure of Alkali-Activated Binary Cements Developed by Combining Ceramic Sanitaryware with Fly Ash or Blast Furnace Slag

Abstract: The properties of a binder developed by the alkali-activation of a single waste material can improve when it is blended with different industrial by-products. This research aimed to investigate the influence of blast furnace slag (BFS) and fly ash (FA) (0–50 wt %) on the microstructure and compressive strength of alkali-activated ceramic sanitaryware (CSW). 4 wt % Ca(OH)2 was added to the CSW/FA blended samples and, given the high calcium content of BFS, the influence of BFS was analyzed with and without adding Ca(OH)2. Mortars were used to assess the compressive strength of the blended cements, and their microstructure was investigated in pastes by X-ray diffraction, thermogravimetry, and field emission scanning electron microscopy. All the samples were cured at 20 °C for 28 and 90 days and at 65 °C for 7 days. The results show that the partial replacement of CSW with BFS or FA allowed CSW to be activated at 20 °C. The CSW/BFS systems exhibited better mechanical properties than the CSW/FA blended mortars, so that maximum strength values of 54.3 MPa and 29.4 MPa were obtained in the samples prepared with 50 wt % BFS and FA, respectively, cured at 20 °C for 90 days.

Microscopic Chemical Characterization and Reactivity in Cementing Systems of Elephant Grass Leaf Ashes.

Abstract: Many agrowastes are being used for energy production by combustion in power plants. This process generates huge amounts of ash, which has a potential pozzolanic activity for blending with Portland cement or hydrated lime. In this paper, the ash obtained from elephant grass (Pennisetum purpureum Schum var. purple) leaves (EGLs) was studied, including the silicon content and its distribution, the presence of other compounds, and in addition, the presence of silica bodies (phytoliths). Combustion temperatures of 450 and 650°C produced an unaltered inorganic skeleton (spodogram), whereas at 850°C, there is a sintering process because of high potassium content in the ash. Phytoliths and different types of hairs were identified, and they contained high percentages of silica. Magnesium (mainly as periclase) was distributed in the most porous parts in the interior of the leaves. The silica can react with calcium hydroxide (pozzolanic reaction) forming calcium silicate hydrates (observed by field-emission scanning electron microscopy and thermogravimetric analysis). Fixed lime percentages at 28 curing days (63%) indicated the high reactivity of EGL ashes in calcium hydroxide pastes due to the pozzolanic reaction. This study demonstrates the possibility of the reuse of ashes from EGLs for the production of environmental-friendly cements.