235 results found
Kia A, Delens J, Wong H, et al., 2021, Structural and hydrological design of permeable concrete pavements, Case Studies in Construction Materials, Vol: 15, ISSN: 2214-5095
Permeable pavements are used to mitigate urban flooding. However, conventional concrete permeable pavements have low compressive strength and are prone to clogging, which degrades performance and reduces service life. A new type of permeable pavement, high-strength clogging resistant permeable pavement (CRP), has recently been developed that overcomes many limitations of conventional permeable pavements. This paper presents a new design methodology for CRP that takes into account both structural and hydrological considerations. This is used in 12 case studies which compare CRP with conventional permeable pavements. The results highlight several advantages of CRP and demonstrate that CRP with low porosity (∼5%) can cope with severe rainfall run-off volumes. The suitability of using CRP in both light and heavy load bearing applications is demonstrated. The research also shows that the use of CRP allows considerable reductions in pavement depth compared to conventional permeable pavements with reduced material costs.
Zhou Y, Lu J, Li J, et al., 2021, Effect of NaCl and MgCl2 on the hydration of lime-pozzolan blend by recycling sewage sludge ash, JOURNAL OF CLEANER PRODUCTION, Vol: 313, ISSN: 0959-6526
Zhou Y-F, Lu J-X, Li J-S, et al., 2021, Hydration, mechanical properties and microstructure of lime-pozzolana pastes by recycling waste sludge ash under marine environment, JOURNAL OF CLEANER PRODUCTION, Vol: 310, ISSN: 0959-6526
Zhang T, Zhou Z, Li M, et al., 2021, Effect of hydrated magnesium carbonate grown in situ on the property of MgO-activated reactive SiO2 mortars, JOURNAL OF SUSTAINABLE CEMENT-BASED MATERIALS, ISSN: 2165-0373
Wu C, Chen C, Cheeseman C, 2021, Size Effects on the Mechanical Properties of 3D Printed Plaster and PLA Parts, JOURNAL OF MATERIALS IN CIVIL ENGINEERING, Vol: 33, ISSN: 0899-1561
Guan Y, Hu Z, Zhang Z, et al., 2021, Effect of hydromagnesite addition on the properties and water resistance of magnesium oxysulfate (MOS) cement, CEMENT AND CONCRETE RESEARCH, Vol: 143, ISSN: 0008-8846
Zhou Y, Lu J, Li J, et al., 2021, Influence of seawater on the mechanical and microstructural properties of lime-incineration sewage sludge ash pastes, CONSTRUCTION AND BUILDING MATERIALS, Vol: 278, ISSN: 0950-0618
Yio M, Yue X, Ji R, et al., 2021, Production of foamed glass-ceramics using furnace bottom ash and glass, Ceramics International, Vol: 47, Pages: 8697-8706, ISSN: 0272-8842
This research has produced foamed glass-ceramics from coal fired power station furnace bottom ash (FBA) and soda-lime-silica glass. The as-received FBA was wet milled with different additions of glass. The resultant slurry was dried and formed into a powder. The powder was pressed and sintered at a range of temperatures with additions of a fluxing agent (sodium tetraborate decahydrate), a bubble stabilising additive (tri-sodium phosphate) and a bloating agent (calcium carbonate) and this produced foamed FBA-glass-ceramics. The effect of glass content and sintering temperature on the properties of the sintered ceramic foams are reported. A range of potential applications including thermal insulation and biological filters for water and wastewater treatment are discussed. The research demonstrates that it is possible to engineer the properties of FBA derived glass-ceramic foams by careful control of the composition and processing conditions in order to transform a problematic waste into commercially interesting materials.
Scott A, Oze C, Shah V, et al., 2021, Transformation of abundant magnesium silicate minerals for enhanced CO2 sequestration, COMMUNICATIONS EARTH & ENVIRONMENT, Vol: 2
Dieckmann E, Onsiong R, Nagy B, et al., 2021, Valorization of waste feathers in the production of new thermal insulation materials, Waste and Biomass Valorization, Vol: 12, Pages: 1119-1131, ISSN: 1877-2641
Poultry has become the primary source of dietary protein consumed globally and as a result the by-product feathers are an increasingly problematic industrial waste. Developing a circular economy for feathers is, therefore, an important research area that provides an opportunity to make use of the unique combination of properties of this abundant natural material. This paper reports on the thermal properties of novel feather-based thermal insulation materials. Waste feathers were collected, cleaned and processed into fibres, which were then used to form air-laid nonwoven materials. These have a high fibre content and exploit the excellent natural thermal insulation properties of feathers. The performance of the novel materials developed are tested in order to outline the influence of temperature and density on thermal conductivity and dynamic water sorption. Results are compared to a range of commercially available thermal insulation materials for buildings manufactured from denim, hemp, sheep wool, PET and mineral wool. It was found that air laid feather-fibre fabrics have comparable performance to other fibrous materials and have a thermal conductivity of 0.033 W/(m K) for samples with a density of 59 kg/m3. This is due to the low thermal conductivity of feather fibres and the void structure formed by air-laid processing that effectively traps air. These materials additionally offer improved sustainability credentials as they are derived from a readily available waste that is generally considered to be unavoidable. The paper concludes by highlighting the significant technical and commercial barriers that exist to using waste feathers in thermal insulation products and suggests areas for further research that can exploit the unique properties of feathers.
Zhang T, Li T, Zhou Z, et al., 2020, A novel magnesium hydroxide sulfate hydrate whisker-reinforced magnesium silicate hydrate composites, Composites Part B: Engineering, Vol: 198, ISSN: 0961-9526
Magnesium hydroxide sulfate hydrate (MHSH) whiskers are used to reinforce magnesium silicate hydrate (M-S-H) cement mortars as novel microfibrous materials because of their similar pH. The microstructure, mechanical performance, and reinforcement mechanism were investigated, and the results showed that the addition of between 1 and 5 wt% MHSH whiskers improved the compressive and flexural strengths of M-S-H cement mortars. The optimal compressive and flexural strengths were obtained at MHSH whisker contents between 3 and 4 wt%. The MHSH whiskers had a limited effect on the toughness of M-S-H cement, and mortars reinforced with MHSH whiskers exhibited brittle failure due to the small size of MHSH whiskers and low fiber bridging traction. Scanning electron microscopy (SEM) revealed that the microscale reinforcement mechanism of MHSH whiskers involved whisker pullout, crack deflection, whisker-cement coalition pullout, and whisker fracture. These mechanisms helped dissipate energy and optimize the stress distribution and transfer, which were crucial to improving the flexural strength. The SEM images revealed the rough and grooved surfaces of MHSH whiskers, and X-ray photoelectron spectroscopy (XPS) showed the presence of polar functional groups on the surface which resulted in the adhesion of M-S-H gel on MHSH whiskers due to good interfacial bonding. The mercury intrusion porosimetry (MIP) results indicated that the addition of MHSH whiskers reduced the porosity of M-S-H cement mortars, which also contributed to the increased compressive strength.
Vilchez V, Dieckmann E, Tammelin T, et al., 2020, Upcycling Poultry Feathers with (Nano)cellulose: Sustainable Composites Derived from Nonwoven Whole Feather Preforms, ACS Sustainable Chemistry & Engineering, Vol: 8, Pages: 14263-14267, ISSN: 2168-0485
Ferraro A, Colangelo F, Farina I, et al., 2020, Cold-bonding process for treatment and reuse of waste materials: Technical designs and applications of pelletized products, Critical Reviews in Environmental Science and Technology, Vol: 51, Pages: 2197-2231, ISSN: 1064-3389
This work provides a comprehensive review of research on the cold-bonding pelletization process used to produce lightweight aggregates (LWAs) using waste materials, to valorize the waste and, at the same time, minimize risks related to disposal. Research investigating various aspects of the cold-bonding process highlight: i) feasible mix-designs for pellet production; ii) the most relevant operating parameters affecting the process; and iii) the potential applications of the LWAs produced. The analysis gives a wide overview of the fundamental key-points that control the cold-bonding process. Data comparison provides a useful way to identify the optimal process conditions to allow development of optimum products. This involves the selection of the correct mix-design, including suitable binders and potential additives, and the selection of appropriate operating conditions, which are a function of the waste investigated, and/or waste mix characteristics. The review proposes an optimized approach to experimental studies on cold-bonding processes that has potential to enhance future process performance. Moreover, the present work provides a complete framework useful for decision-making for both manufacturers and researchers working to use this promising technique.
Zhao Y, Dieckmann E, Cheeseman C, 2020, Low-temperature thermal insulation materials with high impact resistance made from feather-fibres, Materials Letters: X, Vol: 6, Pages: 1-5, ISSN: 2590-1508
Thermal insulation materials typically used in low-temperature applications such as pipelines for transporting liquid natural gas can become brittle and are therefore susceptible to impact damage. New feather-fibre biomaterials developed in this work have extremely low thermal conductivity but retain high impact resistance at low-temperatures. The experiments reported demonstrate the improved impact resistance of feather fibre biomaterials compared to foamed nitrile rubber. The microstructural characteristics of feather-fibre biomaterials that allow them to be used as impact resistant thermal insulation at low-temperatures are discussed.
Zhou Y-F, Li J-S, Lu J-X, et al., 2020, Sewage sludge ash: A comparative evaluation with fly ash for potential use as lime-pozzolan binders, Construction and Building Materials, Vol: 242, Pages: 1-10, ISSN: 0950-0618
The disposal of sewage sludge ash (SSA) has become an environmental issue due to the limited available landfill space. This study aims at applying the finely-ground sewage sludge ash (FSSA) with quicklime and hydrated lime to develop a new type of lime-pozzolan system and study the effects of different types of lime on the mechanical properties of the systems. A traditional pozzolanic material (i.e. coal fly ash (FA)) was also used to compare with the FSSA. Multiple techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were used to assess the hydration kinetics and microscopic characteristics of the lime-pozzolan systems. The results showed that the quicklime system exhibited lower strength than the hydrated lime system, which was due to its lower reaction degree with the FSSA and the higher porosity caused by the expansion during the vigorous hydration reaction of quicklime. Compared to FA, the FSSA attained higher strength for the whole curing period (up to 90 d) in the lime system due to the highly porous nature of FSSA leading to a lower effective water to binder ratio. However, in the hydrated lime system, due to the higher overall pozzolanic activity of FA, its long-term strength values gradually improved. Besides, calcium phosphate hydrate crystals were detected by XRD in the FSSA; while some clinotobermorite was found in the FA both from XRD and SEM, which might govern the strength gain in the lime-FA system. Overall, the application of FSSA as a pozzolan in the lime-pozzolan system could be a promising option to both relieve the waste disposal pressure and provide a potential sustainable construction material.
Fang L, Wang Q, Li J-S, et al., 2020, Feasibility of wet-extraction of phosphorus from incinerated sewage sludge ash (ISSA) for phosphate fertilizer production: A critical review, Critical Reviews in Environmental Science and Technology, Pages: 1-33, ISSN: 1064-3389
Dieckmann E, Sheldrick L, Tennant M, et al., 2020, Analysis of barriers to transitioning from a linear to a circular economy for end of life materials: a case study for waste feathers, Sustainability, Vol: 12, Pages: 1725-1725, ISSN: 2071-1050
This research aimed to develop a simple but robust method to identify the key barriers to the transition from a linear to a circular economy (CE) for end of life products or material. Nine top-tier barrier categories have been identified that influence this transition. These relate to the basic material properties and product characteristics, the availability of suitable processing technology, the environmental impacts associated with current linear management, the organizational context, industry and supply chain issues, external drivers, public perception, the regulatory framework and the overall economic viability of the transition. The method provides a novel and rapid way to identify and quantitatively assess the barriers to the development of CE products. This allows mitigation steps to be developed in parallel with new product design. The method has been used to assess the potential barriers to developing a circular economy for waste feathers generated by the UK poultry industry. This showed that transitioning UK waste feathers to circularity faces significant barriers across numerous categories and is not currently economically viable. The assessment method developed provides a novel approach to identifying barriers to circularity and has potential to be applied to a wide range of end of life materials and products.
Zhang T, Zou J, Li Y, et al., 2020, Stabilization/Solidification of Strontium Using Magnesium Silicate Hydrate Cement, Processes, Vol: 8, Pages: 163-163, ISSN: 2227-9717
<jats:p>Magnesium silicate hydrate (M–S–H) cement, formed by reacting MgO, SiO2, and H2O, was used to encapsulate strontium (Sr) radionuclide. Samples were prepared using light-burned magnesium oxide and silica fume, with sodium hexametaphosphate added to the mix water as a dispersant. The performance of the materials formed was evaluated by leach testing and the microstructure of the samples was also characterized. The stabilizing/solidifying effect on Sr radionuclide in the MgO–SiO2–H2O system with low alkalinity is demonstrated in the study. The leaching rate in a standard 42-day test was 2.53 × 10−4 cm/d, and the cumulative 42-day leaching fraction was 0.06 cm. This meets the relevant national standard performance for leaching requirements. Sr2+ was effectively incorporated into the M–S–H hydration products and new phase formation resulted in low Sr leaching being observed.</jats:p>
Fang L, Li J-S, Donatello S, et al., 2020, Use of Mg/Ca modified biochars to take up phosphorus from acid-extract of incinerated sewage sludge ash (ISSA) for fertilizer application, Journal of Cleaner Production, Vol: 244, Pages: 1-11, ISSN: 0959-6526
Recovery of phosphorus (P) from incinerated sewage sludge ash (ISSA) by biochar is an attractive solution for mitigating the P scarcity and transferring waste to resources. This work used Mg/Ca-modified biochars to take up P from the acid-extract from ISSA at low pH (<2), which simplified the previous P recycling process. The hypothesis is to produce a P-enriched post-sorption biochar that can be directly applied as a P fertilizer. Wastes of peanut shell and sugarcane bagasse were used to synthesize Mg/Ca-modified biochars at pyrolysis temperatures of 450 °C, 700 °C and 850 °C. Preliminary results indicated Mg-modified sugarcane bagasse biochar pyrolysed at 700 °C produced optimal P-absorption. This biochar was positively charged and had a high specific surface area (1440 m2/g), consistent with a layered porous structure. The optimal biochar showed rapid adsorption of P which could be described by the pseudo-second-order model. Successful adsorption of P from the acid-extract by the optimal biochar was mainly due to chemical precipitation and its adsorption capacity is 129.79 mg P/g biochar.
Zhou Y-F, Li J-S, Lu J-X, et al., 2020, Recycling incinerated sewage sludge ash (ISSA) as a cementitious binder by lime activation, Journal of Cleaner Production, Vol: 244, Pages: 1-10, ISSN: 0959-6526
Incineration is used to manage sewage sludge in many countries and regions including Hong Kong. This generates a huge amount of incinerated sewage sludge ash, the disposal of which is an environmental issue. In this research, an eco-friendly cementitious binder was developed by adding 10, 20, and 30 wt % of lime into sludge ash to obtain different lime/sewage sludge ash ratios. The same amounts of ordinary Portland cement were also added to the equivalent batches of sewage sludge ash for comparing the two systems. Paste samples were characterised for heat of hydration, mechanical properties and thermogravimetric analysis. Microstructural analysis using X-ray diffraction and scanning electron microscopy and the factors controlling strength development are reported. The results show that sewage sludge ash accelerated the hydration rate of cement, and the lime pastes with sewage sludge ash showed larger amounts of heat and higher reactivity than the cement pastes with sewage sludge ash. Considering the lime-based binder was mainly proposed for the production of controlled low strength materials, within the lime system the optimum mechanical properties (compressive strength) were achieved by the 30% lime with sewage sludge ash mix and the strength value showed remarkable improvement from 28 to 90 days of curing. The crystalline phases responsible for the strength development in the lime-based system were mainly brushite and calcium phosphate hydrates. The lime with sewage sludge ash mix has potential to be used for the development of new controlled low-strength materials.
Li JS, Fang L, Wang Q, et al., 2020, Phosphorus (P) recovery and reuse as fertilizer from incinerated sewage sludge ash (ISSA), Current Developments in Biotechnology and Bioengineering: Resource Recovery from Wastes, Pages: 263-288, ISBN: 9780444643223
Phosphorus (P), an essential macromineral, is fundamental to all living things. Alarmingly, P is consumed in excess in most countries, and the known P source will be run out within several decades. Therefore, looking for alternative P sources from P-bearing wastes is significant and urgent, which can not only recycle P resources but also avoid the huge cost of disposing these wastes. P-rich incinerated sewage sludge ash (ISSA) is a by-product of the incineration process of dewatered sewage sludge generated from sewage treatment plants. The P in the ISSA, if economically and environmentally recycled, can achieve the sustainable management of sewage sludge and P resources. In this chapter, the comprehensive physical and chemical characteristics of Hong Kong ISSA are discussed. The leachability and the associated environmental risk of metal(loid)s from the ISSA are highlighted in an attempt to improve the public perception of sewage sludge incineration from an environmental perspective. Afterward, a series of laboratory-scale processes for extracting P from the ISSA to form fertilizer products (Ca-P and struvite) are introduced. Especially, an innovative two-step extraction method and a struvite crystallization technology are developed to obtain a P extract with high purity. In addition, the characteristics and reuse values of P-free ISSA are evaluated. Lastly, future research needs are assessed with emphasis placed on P reclamation from the ISSA and application in agriculture. This chapter reviews the state-of-the-art recycling options of ISSA and thereby proposes innovative technologies to use ISSA as a valuable resource by extracting P and producing fertilizers.
Nakic D, Vouk D, Serdar M, et al., 2020, Use of MID-MIX® treated sewage sludge in cement mortars and concrete, European Journal of Environmental and Civil Engineering, Vol: 24, Pages: 1483-1498, ISSN: 1964-8189
Developing beneficial applications for sewage sludge is a key challenge in many countries, given the amount of sludge generated and the disposal or recycling options currently available. Sewage sludge from the wastewater treatment plant at Koprivnica in Croatia has been treated using MID-MIX ® technology that involves the addition of Ca(OH) 2 and CaO to dewatered sludge. This produces a low-density non-hazardous white-grey powder. The treated sewage sludge has been heated to 800, 900 and 1000 °C to form MID-MIX ® treated sewage sludge ash with reduced organic content. MID-MIX ® treated sewage sludge and ash have been used to replace 10 and 20% of cement in mortar and concrete samples. The addition of MID-MIX ® treated sewage sludge causes a significant increase in void content which reduces the mechanical properties and durability of mortar and concrete samples. However, replacement of cement by MID-MIX ® ash did not significantly affect the strength, water penetration or gas permeability compared to control samples. Leaching tests on MID-MIX ® powder, MID-MIX ® ash and mortar samples produced low levels of heavy metal release. The research shows that thermally processed MID-MIX ® treated sewage sludge produces an ash product that has potential to be beneficially used in cementitious materials for selected applications.
Zhang T, Li T, Zou J, et al., 2019, Immobilization of radionuclide 133Cs by magnesium silicate hydrate cement, Materials (Basel), Vol: 13, ISSN: 1996-1944
The radionuclide cesium (Cs) was solidified using magnesium silicate hydrate (M-S-H) cement. The influence of Cs+ on the reaction of the M-S-H gel system was evaluated by measuring the compressive strength and microscopic properties of the solidified body. By testing the impact resistance, leaching resistance and freeze-thaw resistance of the solidified body, the immobilizing ability of Cs+ by the M-S-H cement was analyzed. Results indicate that Cs+ only slightly affects the reaction process of the M-S-H gel system, and only slows down the transformation rate of Mg(OH)2 into the M-S-H gel to a certain extent. The M-S-H cement exhibits superior performance in solidifying Cs+. Both the leaching rate and cumulative leach fraction at 42 d were considerably lower than the national requirements and better than the ordinary Portland cement-solidified body. The curing effect of the M-S-H cement on Cs+ is mainly physical encapsulation and chemisorption of hydration products.
Dieckmann E, Nagy B, Yiakoumetti K, et al., 2019, Thermal insulation packaging for cold-chain deliveries made from feathers, Food Packaging and Shelf Life, Vol: 21, Pages: 1-8, ISSN: 2214-2894
This paper reports on new thermal insulation packaging materials made from feathers. Clean and disinfected feathers from the poultry industry have been processed into fibres and air laid using commercial pilot-plant facilities to form non-woven feather fibre composite mats. This process can produce materials with different thickness and density by varying the processing conditions and mat composition. The thermal performance of non-woven feather fibre packaging liners has been compared to expanded polystyrene (EPS) to assess the potential for use in temperature-controlled deliveries. Experiments involved monitoring the time-temperature profile of meat substitute materials and coolants stored inside cardboard boxes lined with thermal insulation. The results show that feather fibre composite insulation has comparable thermal performance to EPS and may out-perform EPS under some conditions. It is concluded that low-cost, lightweight and sustainable non-woven feather fibre liners have potential to displace the materials currently used for delivering chilled and frozen foods and other products susceptible to degradation by high temperatures during delivery.
Chen Z, Wang H, Ji R, et al., 2019, Reuse of mineral wool waste and recycled glass in ceramic foams, Ceramics International, Vol: 45, Pages: 15057-15064, ISSN: 0272-8842
Novel ceramic foams have been prepared by high temperature sintering of waste mineral wool and waste glass using SiC as a foaming agent. The aim of the research was to understand the effects of composition and sintering conditions on the properties and microstructure and produce commercially exploitable ceramic foams. Optimum ceramic foams were formed from 40 wt% mineral wool waste and 2 wt% SiC, sintered at 1170 °C using a heating rate of 20 °C/min with a 20 min hold at peak temperature. The ceramic foams produced had a bulk density of 0.71 g/cm3 and a uniform pore size distribution. The research shows that ceramic foams can be formed from waste mineral wool and these can be used for thermal insulation with associated economic and environmental benefits.
Chen X, Zhang T, Bi W, et al., 2019, Effect of tartaric acid and phosphoric acid on the water resistance of magnesium oxychloride (MOC) cement, Construction and Building Materials, Vol: 213, Pages: 528-536, ISSN: 0950-0618
Magnesium oxychloride (MOC) cement is featured with high early strength, low thermal conductivity and low density, but is not widely applied in construction engineering due to its poor water resistance capability. This research has studied the effect of phosphoric acid and tartaric acid additions on the water resistance of MOC cement pastes, in which also reports the effects on setting time, hydration reactions, compressive strength, phase composition, thermal stability and microstructure. 1 wt% of phosphoric acid and tartaric acid additions can improve the water resistance and reduce thermal stability of MOC cement pastes, which is associated with formation of gel-like 5Mg(OH) 2 ·MgCl 2 ·8H 2 O. Moreover, these additions reduce the compressive strength and prolong the setting time of MOC cement pastes, as well as increase the total porosity, the volume fraction of gel pores (<10 nm) and large pores (>100 nm), however, decrease the volume fraction of small capillary pores (10–100 nm) of MOC cement pastes. These effects are caused by both additives but are most pronounced for MOC cement pastes containing phosphoric acid. In addition, 2Mg(OH) 2 ·MgCl 2 ·2H 2 O is a transitional phase in the formative stage of 5Mg(OH) 2 ·MgCl 2 ·8H 2 O in MOC cement.
Dieckmann E, Eleftheriou K, Audic T, et al., 2019, New sustainable materials from waste feathers: Properties of hot-pressed feather/cotton/bi-component fibre boards, Sustainable Materials and Technologies, Vol: 20, ISSN: 2214-9937
Feathers from poultry are an abundant, globally available waste. The current beneficial reuse for feathers involves autoclaving them to produce feather meal, an animal feed with low economic value. This paper reports on the production and performance of new feather-derived materials. These have potential to provide a higher value application for waste feathers. Feather fibres, cotton fibres and polyethylene/polypropylene bi-component fibres (blended 55:20:25 by weight) have been air-laid to form 20 mm thick non-woven pre-forms with a density of 0.14 g cm −2 . These were then hot pressed to produce materials with significantly higher density and improved properties. Optimum materials were formed by hot pressing between 150 and 160 °C at 6 MPa for 1 min. Lower temperatures resulted in poor fibre bonding and fibre pull-out during fracture. Higher temperatures caused thermal degradation of the feather fibres. The optimum feather fibre boards with a density of 0.77 g/cm 3 , corresponding to 31.3% porosity, had tensile strengths of 17.9 MPa a tensile modulus of 1.74 GPa and an elongation at fracture of 5.9%. These samples exhibited fibre fracture during tensile testing. Feather fibre boards have similar tensile strength, density and Young's modulus to particleboard, organic resin particleboard and flake board. Quantitative estimates of the economic and environmental benefits from using feather fibres to form feather fibre boards are discussed. The research advances sustainability by providing a new potential circular economy outlet for waste feathers and is part of on-going research to develop novel applications that exploit the unique properties of feathers.
Kia A, Wong H, Cheeseman C, 2019, High-strength clogging resistant permeable pavement, International Journal of Pavement Engineering, Vol: 22, Pages: 271-282, ISSN: 1029-8436
Permeable pavement is utilised in order to alleviate flooding in towns, cities and other urban areas, but it is prone to clogging, has relatively low strength and requires regular maintenance. We have developed a novel permeable pavement with low tortuosity pore structure that can be cast on-site that is not only resistant to clogging, but also has high permeability and strength. This high strength clogging resistant permeable pavement (CRP) was prepared by introducing straight pore channels of varying size and number into self-compacting mortar. Samples with porosity ranging from 2 to 32% were tested. In all cases, permeability and compressive strength were substantially higher than conventional permeable concrete. More significantly, CRP can be engineered with low porosity (5%), high strength (> 50 MPa) and high permeability (> 2 cm/s), but does not clog despite extensive cyclic exposure to flow containing sand and clay. A simple method to model the permeability of CRP from the pore structure is described. We report for the first time a high strength clogging resistant permeable pavement capable of retaining sufficient porosity and permeability for storm-water infiltration without requiring frequent maintenance. This innovative system will help alleviate urban flooding and contribute towards a more sustainable urbanisation.
Kinnunen P, Sreenivasan H, Cheeseman CR, et al., 2019, Phase separation in alumina-rich glasses to increase glass reactivity for low-CO<inf>2</inf> alkali-activated cements, Journal of Cleaner Production, Vol: 213, Pages: 126-133, ISSN: 0959-6526
Ways to reduce cement-related carbon emissions are actively sought. One possible solution is partial substitution of Portland cement by alkali-reactive glass. We report on low-CO2 glass compositions that have high alkali solubility derived from industrial basaltic stone wool compositions. We found that highly alkali-soluble glasses can be formed with glass compositions that in principle can be made using silicate minerals which have no raw material-related CO2 emissions. The reason behind the reactivity of these glasses is thought to be caused by the dilution of the main network-forming species, silicon, which is further enhanced by phase separation, forming phases with high-silicon and low-silicon concentrations. Phase separation in alumina-rich samples is further studied and occurs at moderate cooling rates. The effect of glass-glass phase separation is discussed in the context of reactive glasses in cementitious systems. The results indicate that controlled phase separation could decouple CO2 emissions from the reactivity of glassy supplementary cementitious materials.
Auwerter LCC, Templeton MR, van Reeuwijk M, et al., 2019, Development of porous glass surfaces with recoverable hydrophobicity, Materials Letters: X, Vol: 1, ISSN: 2590-1508
Porous glass tiles have been reacted with a low-surface energy coating to produce hydrophobic surfaces. Washing the surface with surfactant reduces hydrophobicity and the wetting state changes from Cassie-Baxter to Wenzel. Passing air through the porous glass when it is immersed in water causes a solid-gas-liquid interface to form and this is associated with recovery of hydrophobicity. The processing and microstructural characteristics of the porous glass that show this effect are reported. Potential applications include low-friction pipes, where maintaining the Cassie-Baxter state at the water-pipe interface would significantly reduce the energy required to transport water.
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