Development of ambient-cured geopolymer mortars with construction and demolition waste-based materials

YesDegrading infrastructure and applications of structural demolition create tremendous amounts of construction and demolition waste (CDW) all around the world. To address this issue in an effective way, recycling CDW in a most appropriate way has become a global concern in recent years. To this end, this study focused on the valorization of CDW-based materials such as tile, bricks, glass, and concrete in the development of geopolymer mortars. CDWs were first collected from demolition zone and then subjected to crushing-milling operations. To investigate the influence of slag (S) addition to the mixtures, 20% S substituted mixture designs were also made. Fine recycled concrete aggregates (FRCA) obtained from crushing and sieving of the waste concrete were used as the aggregate. A series of mixtures were designed using different proportions of three distinct alkali activators such as sodium hydroxide (NaOH), sodium silicate (Na2SiO3), and calcium hydroxide (CH; Ca(OH)2). To improve their applicability, the mixtures were left to cure at room temperature rather than the heat curing which is frequently applied in the literature. After 28 days ambient curing, the 100% CDW-based geopolymer mortar activated with three different activators reached a compressive strength of 31.6 MPa, whereas the 20% S substituted geopolymer mortar showed a 51.9 MPa compressive strength. While the geopolymer mortars activated with only NaOH exhibited poor performance, it was found that the use of Na2SiO3 and CH improved the mechanical performance. Main geopolymerization products were related to NASH (Sodium alumino-silicate hydrate), CASH (Calcium alumino-silicate hydrate), and C(N)ASH gel formations. Results demonstrated that mixed CDWs can be employed in the manufacturing geopolymers, making them potential alternatives to Portland cement (PC)-based systems by being eco-friendly, energy-efficient, and comparable in compressive strength.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 894100

Characterization and life cycle assessment of geopolymer mortars with masonry units and recycled concrete aggregates assorted from construction and demolition waste

YesDeveloping a fast, cost-effective, eco-friendly solution to recycle large amounts of construction and demolition waste (CDW) generated from construction industry-related activities and natural disasters is crucial. The present investigation aims to offer a solution for repurposing CDW into building materials suitable for accelerated construction and housing in developing countries and disaster-prone areas. Feasibility of recycled concrete aggregate (RCA) inclusion in geopolymer mortars constituted entirely from CDW (masonry elements) was investigated via an environmental impact-oriented approach by addressing the composition related key parameters. Mechanical performance was evaluated through compressive strength tests, and scanning electron microscope (SEM) imaging with line mapping analyses were carried out to monitor the interfacial transition zone (ITZ) properties. To investigate the environmental impacts of the geopolymer mortars and highlight the advantages over Portland cement-based mortars, a cradle-to-gate life cycle assessment (LCA) was performed. Findings revealed that roof tile (RT)-based geopolymer mortars mainly exhibited better strength performance due to their finer particle size. Mixtures activated with 15 M NaOH solution and cured at 105 °C achieved an average compressive strength above 55 MPa. RCA size was the most influential parameter on compressive strength, and a smaller maximum RCA size significantly increased the compressive strength. Microstructural analyses showed that the ITZ around smaller RCAs was relatively thinner, resulting in better compressive strength results. LCA proved that CDW-based geopolymer mortars provide the same compressive strength with around 60% less CO2 emissions and similar energy consumption compared to Portland cement-based mortars.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 894100. The authors also wish to acknowledge the support of the Scientific and Technical Research Council of Turkey (TUBITAK) provided under project: 117M44

Development of ambient-cured geopolymer mortars with construction and demolition waste-based materials

YesDegrading infrastructure and applications of structural demolition create tremendous amounts of construction and demolition waste (CDW) all around the world. To address this issue in an effective way, recycling CDW in a most appropriate way has become a global concern in recent years. To this end, this study focused on the utilization of CDW-based materials such as hollow brick (HB), red clay brick (RCB), roof tile (RT), glass (G) and concrete (C) in the production of geopolymer mortars. These materials were first collected from an urban transformation area and then subjected to an identical two-step crushing-milling procedure to provide sufficient fineness for geopolymerization. To investigate the influence of blast furnace slag (S) addition to the CDW-based mixtures, 20% S substituted mixture designs were also made. Fine recycled concrete aggregates (FRCA) obtained from crushing and sieving of the waste concrete were used as the aggregate. A series of mixtures were designed using different proportions of three distinct alkali activators such as sodium hydroxide (NaOH), sodium silicate (Na2SiO3) and calcium hydroxide (Ca[OH]2). To improve their applicability, the mixtures were left to cure at room temperature rather than the heat curing which is frequently applied in the literature. After 28 days of ambient curing, the 100% CDW-based geopolymer mortar activated with three different activators reached a compressive strength of 31.6 MPa, whereas the 20% S substituted geopolymer mortar achieved a compressive strength of 51.9 MPa. While the geopolymer mortars activated with only NaOH exhibited poor performance, it was found that the use of Na2SiO3 and Ca(OH)2 improved the compressive strength. Main geopolymerization products were related to NASH, CASH, and C(N)ASH gel formations. Our results demonstrated that mixed CDW-based materials can be employed in the manufacturing geopolymers, making them potential alternatives to Portland cement-based systems by being eco-friendly, energy-efficient, and comparable in compressive strength.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 894100

Length-weight relationship and condition factor as an indicator of growth and feeding intensity of Sea bream (Sparus aurata L, 1758) given feed with different protein contents

WOS: 000466335700017The aim of this study is to investigate the relationship between the length-weight and the condition factor of gilthead sea bream (Sparus aurata L., 1758) fed with three types of feed with different levels of crude protein (A: 38% Crude Protein (CP) and 18% Crude Lipid (CL); B: 42% CP and 18% CL; and C: 45% CP and 18% CL). The length-weight relationship of the fish in groups A, B and C was determined as W=0.051* TL2.63, W=0.046* TL2.67 and W=0.046* TL2.68 respectively and there was no statistically significant difference between the groups (p>0.05). There was negative allometric growth in all experimental groups. The lowest mean value in the groups according to Fulton's condition factor (CF) was found in group B (1.66 +/- 0.17), and the highest mean value was found in group C (1.71 +/- 0.18). It was determined that there was no statistically significant difference between the groups (p>0.05)

Silymarin ameliorates uterine and ovarian damage in streptozotocin induced diabetic rat model

WOS: 000434238100008Diabetes is a systemic disease that affects microvasculature in almost all organs. Uterus and the ovaries may also be a target for diabetes. We investigated effects of diabetes on the uterus and the ovaries and the role of silymarin treatment on the effects of diabetes on uterine and ovarian microenvironment in a diabetic rat model. Seven non-diabetic (control) and fourteen diabetic female mature Sprague-Dawley albino rats were used. Diabetes was induced by intraperitoneal injection of 60 mg/kg streptozotocin and 100 mg/kg oral silymarin and was administered for four weeks to 7 of diabetic rats. After the treatment, blood samples were collected; hysterectomy with bilateral oophorectomy was performed for histopathological examination. Stromal degeneration, follicular degeneration, stromal fibrosis scores of the ovary and gland degeneration and stromal fibrosis scores of endometrium were significantly decreased after silymarin treatment. Silymarin treatment significantly decreased plasma TGF-beta levels and increased plasma AMH (Anti-Mullerian hormone) levels with respect to saline-treated group. This study suggests that silymarin ameliorates the uterine and ovarian damage in a diabetic rat model

EFFECTS OF ANTI-OBSESSIONAL TREATMENT ON PITUITARY VOLUMES IN OBSESSIVE-COMPULSIVE DISORDER

Background: We aimed to examine the effct of anti-obsessional drugs on pituitary gland volumes in the patients with obsessivecompulsive disorder (OCD). Subjects and methods: A group of patients with OCD and of healthy controls were evaluated by using pituitary gland magnetic resonance imaging (MRI) at baseline and after twelve weeks of treatment with selective serotonin re-uptake inhibitors or clomipramine. Results: Pituitary gland volumes were found to be statistically significantly smaller in the patients with OCD compared to healthy control subjects at the beginning of the study. We found that pituitary volumes significantly increased throughout twelve weeks of treatment. Conclusions: This study provides an evidence of the effect of anti-obsessional treatment on the volumes of pituitary gland in OCD patients

Development of Concrete Mixtures Based Entirely on Construction and Demolition Waste and Assessment of Parameters Influencing the Compressive Strength

YesDemolition and reconstruction of degrading structures alongside with the repetitive repair, maintenance, and renovation applications create significant amounts of construction and demolition waste (CDW), which needs proper tackling. The main emphasis of this study has therefore been placed on the development of concrete mixtures with components (i.e., aggregates and binder) coming entirely from CDW. As the binding phase, powdered CDW-based masonry units, concrete and glass were used collectively as precursors to obtain geopolymer binders, which were then incorporated with CDW-based fine and coarse concrete aggregates. Together with the entirely CDW-based concretes, designs were also proposed for companion mixtures with mainstream precursors (e.g., fly ash and slag) occupying some part of the CDW-based precursor combination. Sodium hydroxide (NaOH), sodium silicate (Na2SiO3) and calcium hydroxide (Ca[OH]2) were used at various concentrations and combinations as the alkaline activators. Several factors that have impact on the compressive strength results of concrete mixtures, such as mainstream precursor replacement rate, al-kaline molar concentrations, aggregate-to-binder ratios and curing conditions, were considered and these were also backed by the micro-structural analyses. Our results showed that through proper optimiza-tion of the design factors, it is possible to manufacture concrete mix-tures entirely out of CDW with compressive strength results able to reach up to 40 MPa under ambient curing. Current research is believed to be very likely to promote more innovative and up-to-date techniques to upcycle CDW, which are mostly downcycled through basic practices of road base/sub-base filling, encouraging further research and increas-ing the awareness in CDW issue.The full-text of this paper will be released for public view at the end of the publisher embargo on 1 Jul 2024

Characterisation and standardisation of different-origin end-of-life building materials toward assessment of circularity

YesConstruction and demolition waste (CDW) management and recycling practices are crucial for transitioning to a circular economy. This study focuses on the detailed characterization of CDWs, including hollow brick (HB), red clay brick (RCB), roof tile (RT), concrete (C), and glass (G), collected from seven different sites. The CDWs were characterized based on particle size distribution, chemical composition, and crystalline nature. Pozzolanic activity was evaluated through compressive strength measurements of cement mortars with 20% cement replacement by CDWs at 7, 28, and 90 days. The results showed that clayey CDWs exhibited similar physical/chemical properties and crystalline structures. Compositions of Cs varied significantly based on their original materials. CDWs satisfied the minimum strength activity index for supplementary cementitious materials, with pozzolanic activity influenced by fineness and SiO2+Al2O3 contents. The average strength activity indexes for HB, RCB, RT, C, and G were 84.5%, 86.3%, 83.4%, 80.7%, and 75.8%, respectively. Clayey CDWs contributed to mechanical strength development, while Cs' contribution was related to hydration of unreacted cementitious particles. G exhibited the weakest pozzolanic activity due to its coarser particle size. Overall, CDWs demonstrated suitable properties for use as supplementary cementitious materials in PC-based systems

Properties of geopolymers sourced from construction and demolition waste: A review

YesGeopolymers have been recognised as a viable replacement to ordinary Portland cement (OPC), providing a cleaner solution since it can significantly reduce greenhouse gas emissions as well as accomplishing effective waste recycling. Construction and demolition waste (CDW) has been recently identified as raw materials for geopolymers due to its availability and high contents of silica and alumina. This paper aimed at reviewing the current state-of-the-art on the geopolymer paste, mortar, and concrete production and their properties, with special attention paid to geopolymers incorporating CDWs. The review covers brief assessment of using CDWs in concrete, the mix design of geopolymer mixtures in addition to identification of the main factors influencing the performance of geopolymer containing CDW. The most recent data related to the mechanical and durability properties of CDW-based geopolymers are presented, while the cost and environmental impacts of using recycled materials in producing geopolymer concretes are also discussed. Geopolymer concretes have a vast range of possible applications, however, there are still several barriers facing commercialisation of geopolymers in construction industry. The review indicated that it is possible to produce geopolymer concretes from CDW-based materials with properties comparable to OPC-based ones; however, the selection of proper material composition should be carefully considered, especially under normal curing conditions.The full-text of this article will be released for public view at the end of the publisher embargo on 28 Jan 2023