Cleaner Materials最新文献

In this research, an attempt is made to partially replace ground granulated blast furnace Slag (GGBS) with a binder rich in SiO₂ and CaO in alkali activated slag concrete (AASC) to increase workability and setting time. GGBS is replaced with bagasse ash powder (BAP) in 5%, 10%, and 15% of the binary mix, and subsequently with marble powder (MP) in 5% and 10% of the binary mix. After establishing the best mix for both binder replacements, a ternary mix with 5% BAP and 10% MP is created. The fine aggregates used in the comparison are 100 % river sand and slag sand. 10 M sodium hydroxide and the alkaline to binder ratio is 0.4, were used. Mechanical properties such as compressive strength, split tensile strength, and flexural strength are performed cured at 1, 3, 7, and 28 days samples. To further understand the intrinsic mechanism of strength development, microstructure, morphology and mineralogy on AASC are investigated. Based on the findings, it can be inferred that AASC mixes have a higher strength than OPC mixes. The mechanical strengths of the AASC binary mix with 10% MP and 5% BAP are higher. The microstructural analysis reveals the mixes developed with BAP and 100 % GGBS, had a denser microstructure than the normal mixes. The mechanical properties obtained for most of the AASC mixes are significantly higher than the IRC SP:62-2014 recommendations for rigid pavements for low volume roads.

3D printing process has gained significant attention because of its ability to manufacture complicated geometries. The process also has a lot of potential for reducing plastic waste. In recent years, the use of carbon fiber has become increasingly popular as a reinforcement material for 3D-printed objects. The combination of plastic waste and carbon fiber has the potential to create high-strength and lightweight structures for various applications. This presented paper reviews the advancements in 3D printing using plastic waste, focusing specifically on fused deposition modeling (FDM) and selective laser sintering (SLS) printing methods for carbon fiber composites. The study highlights the important role of materials in the 3D printing process, especially regarding the difficulties in producing non-recyclable plastics. The study highlights composite materials and processes and the industries that utilize these technologies. One of the key aspects of the article is the exploration of the impact of 3D printing on the environment through the recycling of plastic waste. This study shall be helpful for the demonstration of turning 3D printing plastic waste into durable, functional objects while minimizing its environmental impact.

Thermochemical conversion is the most economical approach to recovering energy and alternative fuels from biomass feedstock. This work first reviews the literature data on thermal-oxidative decomposition for common biomass types and forms a database of 18 parameters, including element, proximate, and thermogravimetric analysis (TGA). Then, an Artificial Neural Network (ANN) model is developed for the prediction of TGA data. Pearson correlation coefficient analysis reveals that the influence of environment heating rate on biomass thermal decomposition is larger than that of fuel properties. By inputting biomass elemental/proximate analysis and heating rate, the ANN model successfully predicts 8 key TGA parameters, namely, pyrolysis-onset temperature, peak pyrolysis temperature, oxidation-dominant temperature, peak oxidation temperature, oxidation-end temperature, peak pyrolysis rate, oxidation-dominant rate, and peak oxidation rate, with R² values greater than 0.98. A better performance can be achieved when all ten input features are considered. Final, an open-access online software, Intelligent Fuel Thermal Analysis (IFTA), is developed to predict thermal-oxidative decomposition across a wide range of heating rates and biomass types. This work provides a better understanding of biomass thermal-oxidative decomposition dynamics and a shortcut to obtain key parameters of biomass degradation without TGA tests.

This paper presents the results of a study conducted to develop structural concrete with reduced thermal conductivity, using organic by-products such as Olive Waste (OW) as a lightweight aggregate. Different concrete specimens were elaborated by using two different types of OW and by replacing an equal volume of sand. The first one involved Olive Pomace solid aggregates (OP) while the second type is Olive Pomace solid aggregates immersed in Olive Mill Wastewater (OP_WW). For each type, two series of concrete were produced using OW in both dry and saturated states. The percentage of natural sand substitution by OW ranged from 0% to 15%. The main objective of this study is to experimentally determine whether the mechanical properties and thermal conductivity of the elaborated specimens could be improved compared to the reference concrete. The mechanical tests indicated that the concrete specimens containing 5% of OP_WW in dry state recorded the best mechanical performance compared to the reference concrete. The incorporation of OW also enhances the thermal conductivity of the concrete specimens. Furthermore, the thermal conductivity of this concrete specimen decreased from 1.3 W/m.K for control concrete to 0.86 W/m.K.

Cement asphalt emulsion mixture (CAEM) is an environmentally sustainable substitute for hot mix asphalt and can trigger a substantial economic benefit. This paper systematically reviews the interactions between the organic–inorganic composites and their influence on the performance of CAEM. First, the interactions between asphalt emulsion (AE) and cement are introduced. Next, the demulsification of AE and hydration of cement in the CAEM system are analyzed. Finally, the fresh properties of CA paste, the static and dynamic mechanical properties of CA mortar and its applications in ballastless slab tracks, and the road performance of CAEM and its applications in pavement construction are discussed. This review allows for a better understanding of the interaction of the organic–inorganic composite and thus has a better strategy to regulate the performance of CAEM and promote its practical application.

Reduction of CO₂ emissions and plastic waste are the main environmental problems that modern society is dealing with. Concrete industry is continuously investing in research and development aimed at producing sustainable cementitious materials. In the last decades, it has gained interest the possibility of reusing polymer waste (mainly PET or PP) in partial substitution of natural constituents (aggregates) or as fiber reinforcement. As a matter of fact, because of the poor mechanical characteristic of polymers compared to the one of natural aggregates, the final cementitious composite has reduced mechanical performance. In the aforesaid framework, the experimental research reported in this paper aims at verifying the feasibility of a pathway able to use fine polymer particles, in detail a Polyester resin (PE resin) which is a waste product of the coating industry, as a partial replacement of sand and, in case, of binder particles, upon a gamma irradiation process similar to the one used for the sanification of containers in food industry, also their effectiveness in performing as seeds of the cement hydration. Firstly, intrigued by a study performed by MIT researchers (in which exposure of PET waste particles to gamma irradiation has been investigated as a method to improve their mechanical performance), the influence of different gamma irradiation dosages (10 kGy or 100 kGy) on PE resin particles was investigated. However, results led to the conclusion that, even with a mere 5% by volume substitution of Portland Limestone Cement (PLC) in the mix, the process does not significantly improve the mechanical performance of cement-based composites. In a second stage, the non-irradiated particles have been employed as a replacement of the binder and/or of the sand at different volume replacement ratios (10% and 20% respectively) in mortar mix designs formulated from typical Self-Compacting Concrete (SCC) mixes. Finally, once identified the most suitable type and level of replacement as the best compromise between performance maintenance and volume of added particles, the scaling up to the concrete mix-design has been performed and the related performance thoroughly tested. The results have provided limited reduction in mechanical properties, with a 20% by volume level of substitution of cement by PE resin particles, highlighting the possibility of reusing economically viable quantities of PE resins into concrete while still being able to use the material for structural application.

High-performance ternary mixed nano-concrete has been extensively utilized in high-rise structures due to its desirable strength, durability, and thermal insulation ability. Additionally, nano-concrete usage is the most current area of research in concrete components. This research investigates the compressive strength, flexural behavior, and micro-structure behavior of nano-SiO₂ concrete specimens. This study also evaluates the strength development of mixes combining binary and ternary combinations of agricultural by-products (rice husk ash, corncob ash, and bagasse ash) and industrial by-products (fly ash, ground granulated blast furnace slag, and metakaolin). The cost-efficiency, energy-efficiency, and eco-efficiency of ternary blended nano-concrete with various additives were considered when evaluating their sustainability capabilities. This study aims to improve sustainable high-performance concrete without overutilizing or underutilizing additives. Based on the findings, nano-SiO₂ concrete can achieve greater compressive strength ranges of 51 to 70 MPa with binary and ternary admixtures. Furthermore, ternary nano-SiO₂ concrete performs more sustainably than other mixes regarding cost-effectiveness, energy use, and CO₂ emissions, as do mixes made of sugarcane bagasse ash and ground granulated blast furnace slag.

This study focuses on treating Acid Mine Drainage (AMD) using Recycled Concrete Aggregate (RCA) as a cost-effective and environmentally friendly material. RCA is utilized, considering its availability at low cost, to reduce heavy metal and sulfate concentration in AMD and neutralize its acidity in batch experimental mode. To that end, the adsorptive properties of RCA were characterized before and after adsorption by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), elemental mapping, Brunauer-Emmett-Teller (BET) surface area measurements, and X-ray Diffraction. Furthermore, the organic functional groups of the tested materials were identified by Fourier Transform Infrared Spectroscopy (FT-IR). Adsorption parameters such as dosage, contact time, the grain size distribution of adsorbent particles, and the solution pH, were optimized for enhancing the removal performance. The pH point of zero charges for the RCA sample was defined. The results revealed that RCA is a potential eco-friendly material for AMD treatment. The concentration of sulfate in the tested AMD water was reduced by approximately 84%, while that of the metal elements declined as follows: iron 100%, manganese 95%, copper 66%, zinc 97%, and lead 76%. Also, the pH value of AMD water increased rapidly and reached neutral by using small quantities of RCA (≤1g/L).

Stabilization of flexible pavement layers using geogrids to improve the mechanical response of pavement layers is gaining importance over conventional stabilization techniques due to their low cost and superior performance. However, the lack of experimental data on quantifying the design input parameters of stabilized subgrades or granular layers limits the extensive use of geogrids in the field. Evaluation of design input parameters such as modulus improvement factor (MIF) or layer coefficient ratio (LCR) would promote the use of geogrids in the pavement, reducing the consumption of natural aggregates and the overall project cost. This study attempts to evaluate MIF and LCR due to geogrid stabilized soft subgrades considering different scenarios. All possible combinations of stabilization of pavement layers using biaxial and triaxial geogrids were considered. This involved stabilization of (a) the subgrade layer alone, (b) base layer alone, and (c) subgrade, subbase, and base layers. Accordingly, an extensive, systematic experimental program consisting of eighteen large-scale model pavement experiments (LSMPE) were conducted in five categories (designated as Series I through V). The stabilization of subgrade and granular layers was carried out using commercially available biaxial (BX1 and BX2) and triaxial (TX1) geogrids overlying soft and moderate subgrades with California bearing ratio (CBR) equal to 2.5 and 4%. Test results showed that stabilized subgrade prepared with existing and prepared subgrade material in conjunction with geogrid improved the effective CBR to as high as 10.9% from effective CBR = 7% corresponding to existing and prepared subgrade material without geogrid. The design inputs of geogrids (BX1/BX2/TX1) stabilized granular layers resulted in the MIF and LCR values ranging from 1.9 to 2.8 and 1.31 to 1.63, respectively, for the tested configuration considered in the study. Based on the findings of the study, inputs on resilient modulus of pavement layers were recommended for similar reinforcement and subgrade conditions considered.