Porous asphalt mixtures enriched with bamboo fibers as a new approach for future sustainable construction

Porous Asphalt (PA) is a highly permeable asphalt surface used to create and maintain permeable pavements for storm water management and runoff reduction. Under the impacts of repetitive vehicle loads, warm weather, and heavily rainfall, the structure was vulnerable to deterioration from cracking, rutting, stripping, and quick ageing. This research aims to examine the role of bamboo fiber in improving the physical and mechanical properties and overcome the issue related to PA. Among the tests involve are Cantabro loss, permeability, binder draindown, stability and resilient modulus. Two types of PA gradation involved with four different proportion of bamboo fiber (0.2%, 0.3%, 0.4%, 0.5%). From the findings, it could be conducted that the existence of bamboo fiber can significantly improve the PA performance for both gradations. From this study, the utilization of natural fiber as an additive is also promoted and provide significant contribution to the exploration to alternative pavement material

The Impact of Secondary Phyllosilicate Minerals on the Engineering Properties of Various Igneous Aggregates from Greece

This paper investigates the effect of alteration on the physicomechanical properties of igneous rocks used as aggregates, from various areas from Greece. The studied lithologies include serpentinized dunites, serpentinized harzburgites, serpentinized lherzolites, metamorphic gabbros, diabases, dacites and andesites. Quantitative petrographic analysis shows that the tested samples display various percentages of secondary phyllosilicate minerals. Mineral quantification of the studied rock samples was performed by using the Rietveld method on X-ray diffraction patterns. The samples were also tested to assign moisture content (w (%)), total porosity (nt (%)), uniaxial compressive strength (UCS (MPa)) and Los Angeles abrasion test (LA (%)). The influence of secondary phyllosilicate minerals on the physicomechanical behavior of the tested samples was determined using regression analysis and their derived equations. Regression analysis shows a positive relationship between the percentage of the phyllosilicate minerals of the rocks and the moisture content as well as with the total porosity values. In mafic and ultramafic rock samples, the relationships between the secondary phyllosilicate minerals and their physicomechanical properties have shown that the total amount of the secondary phyllosilicate minerals results negatively on their physicomechanical properties. On the other hand, the low percentage of phyllosilicate minerals in volcanic rocks can’t be able to define their engineering properties

Estimation of the effect of the mineralogical and petrographic characteristics of igneous rocks from central Macedonia on their physicomechanical properties: evaluation of their behaviour as aggregates in construction and environmental applications

Aggregate materials are considered to be rock blocks which are used either individually or by using an adhesive in constructions. Their term as aggregates encompasses the concept of chemical inertia against any adhesive cement. However, these materials are chemically active determining the behavior of the mass in which they are involved. The present thesis uses natural aggregates and more specifically the igneous rocks derived from Veria-Naousa and Edessa region, as reusable mineral reactive materials by investigating the influence of their mineralogical and petrographic characteristics both on their properties as aggregate materials and on their properties in construction and environmental applications. For this reason, 39 rock samples, of ten different igneous lithotypes, were collected and investigated. The majority of the studied samples are igneous rocks which belong to the Veria-Naousa and Edessa ophiolite complexes, while the rest of them have been collected from their surrounded areas without having any genetic relationship with the first. In more detail, from the aforementioned areas, 14 ultramafic rock samples as well as 10 mafic rock samples were collected, evenly distributed over the wider area of the two investigated ophiolite complexes. Moreover, 6 Pleiocene volcanic rock samples belonging to the subsequent volcanic eruption of Almopia were collected and examined. Finally, 9 granitoid rock samples were also collected in order to investigate their properties. In the total of the already mentioned lithotypes, the interdependence of their properties related to their mineralogical and petrographic characteristics as well as their suitability as concrete aggregates were investigated. Particular emphasis was placed on the study of the effect of secondary phyllosilicate minerals on both the properties of the aggregates and on the final behavior of each technical application wherein contained in order to better understand and predict the potential failures in various construction applications.In addition, in order to investigate the direct supervisory (qualitative and quantitative) influence of the type of the used aggregate on the produced concretes, 64 concrete specimens were prepared from 32 different mixes of igneous rocks for the identification of the influence of the mineralogical and petrographic characteristics of the studied rocks on the final strength as well as on the final quality of the produced concretes. Concrete constitutes a chemically complex mix of cement, water and aggregate materials in various sizes and proportions. The aggregate materials are the basic component of this mixture and therefore possess one of the most important factors in the final quality of the concrete produced. The aggregates contained in concrete, possessing specific proportions of minerals, are active chemical phases where they constantly react with the other components of the concrete to determine its final quality. The most important characteristics of concrete aggregates, which were found to be likely to adversely affect the final mechanical strength of the product, were found to be their surface texture (microroughness), their physical properties, the existence of swelling clay minerals and their uniaxial compressive strength. Moreover, in this thesis, following the principles of cyclic economy and sustainability, the mineral raw materials, evaluated as aggregates and as concrete aggregates, were reused in order to solve a major environmental problem, which focuses on the remediation, in lab scale, of the drainage waste water of Agios Philippos mine (Kirki, 17 km NNW of Aleksandroupoli) which is continuously supplied by meteoric waters that lead to the pit after first having decomposed oxidized mineral ores and particularly sulphides of the open excavation. The oxidation of the sulphide ores of the investigated area occurs through a series of reactions involving direct, indirect and bacterially controlled mechanisms. Some oxidation reactions result in the production of instant acidity, while others cause the dissolution and the removal of heavy metals. During this thesis, for the remediation of the mentioned phenomenon in lab scale, static as well as experimental electrically continuous flow driven forced devices were constructed using multi-mineral line filters. Particularly effective with regard to pH remediation but also to removal or significant reduction of heavy metal concentrations such as Fe, Cu, Pd, Zn has been shown to affect the reuse of magnesite, serpentinite, peat and biochar within the filters of the experimental devices.Ως αδρανή υλικά θεωρούνται τα τεμάχια πετρώματος τα οποία χρησιμοποιούνται είτε αυτούσια είτε με χρήση κάποιου συγκολλητικού μέσου στα τεχνικά έργα. Η ονομασία τους ως αδρανή υλικά εμπεριέχει την έννοια της χημικής αδράνειας έναντι οποιασδήποτε συγκολλητικής κονίας. Στην πραγματικότητα όμως πρόκειται για υλικά χημικά ενεργά που καθορίζουν τη συμπεριφορά της μάζας στην οποία συμμετέχουν. Η παρούσα διατριβή χειρίζεται τα φυσικά αδρανή υλικά ως ενεργές επαναχρησιμοποιούμενες ορυκτές πρώτες ύλες εξετάζοντας την επίδραση των ορυκτοπετρογραφικών χαρακτηριστικών των μαγματικών πετρωμάτων της Βέροιας-Νάουσας και Έδεσσας τόσο στις ιδιότητες τους ως αδρανή υλικά, όσο και στις ιδιότητες τους εντός κατασκευαστικών και περιβαλλοντικών εφαρμογών. Με αυτό το σκοπό συλλέχθηκαν και εξετάστηκαν 39 δείγματα, δέκα διαφορετικών τύπων μαγματικών πετρωμάτων. Η πλειοψηφία των εξεταζόμενων δειγμάτων αποτελούν μαγματικά πετρώματα τα οποία ανήκουν στα οφιολιθικά συμπλέγματα Βέροιας-Νάουσας και Έδεσσας, ενώ τα υπόλοιπα μαγματικά πετρώματα συλλέχθηκαν από γειτνιάζουσες περιοχές με τα οφιολιθικά συμπλέγματα, χωρίς να φέρουν ταυτόχρονη γενετική σχέση με αυτά. Αναλυτικότερα από τις προαναφερθείσες περιοχές συλλέχθηκαν 14 υπερβασικά δείγματα καθώς και 10 βασικής σύστασης πετρώματα, ομοιόμορφα κατανεμημένα στην ευρύτερη περιοχή των δύο υπο εξέταση οφιολιθικών συμπλεγμάτων. Επίσης, συλλέχθηκαν και εξετάστηκαν 6 Πλειοκαινικά ηφαιστειακά πετρώματα τα οποία ανήκουν στην μετέπειτα ηφαιστειότητα της Αλμωπίας. Τέλος, συλλέχθηκαν 9 γρανιτοειδή δείγματα προς διερεύνηση των ιδιοτήτων τους. Στο σύνολο των προαναφερθέντων λιθοτύπων διερευνήθηκε η αλληλεξάρτηση των ιδιοτήτων τους από τα ορυκτοπετρογραφικά τους χαρακτηριστικά και η τελική καταλληλότητα τους ως αδρανή υλικά σκυροδεμάτων. Ιδιαίτερη έμφαση αποδόθηκε στην μελέτη της επίδρασης των δευτερογενών φυλλοπυριτικών ορυκτών τόσο στις ιδιότητες των αδρανών υλικών όσο και στην τελική συμπεριφορά εκάστου τεχνικού έργου όπου περιέχονται με απώτερο σκοπό τη διάγνωση και πρόβλεψη αστοχιών σε διάφορες κατασκευαστικές εφαρμογές. Επιπλέον με σκοπό τον άμεσο εποπτικό (ποιοτικό και ποσοτικό) επηρεασμό του είδους του χρησιμοποιούμενου αδρανούς υλικού στα παραγόμενα σκυροδέματα παρασκευάστηκαν 64 συνολικά σκυροδέματα από 32 διαφορετικά μαγματικά πετρώματα ώστε να εντοπιστεί και να τεκμηριωθεί πετρογραφικά η επίδραση των ορυκτοπετρογραφικών χαρακτηριστικών των πετρωμάτων στην τελική αντοχή και ποιότητα των παραγόμενων σκυροδεμάτων. Το σκυρόδεμα αποτελεί ένα σύνθετο χημικά μίγμα τσιμέντου, νερού και αδρανών υλικών σε διάφορες κοκκομετρίες και αναλογίες. Τα αδρανή υλικά αποτελούν το βασικό σκελετικό στέλεχος αυτού του μίγματος και ως εκ τούτο κατέχουν έναν από τους σημαντικότερους παράγοντες ως προς την τελική ποιότητα του παραγόμενου σκυροδέματος. Τα αδρανή υλικά τα οποία εμπεριέχονται στα σκυροδέματα, κατέχοντας συγκεκριμένες αναλογίες ορυκτολογικών συστατικών, αποτελούν ενεργές χημικές φάσεις όπου αντιδρούν συνεχώς με τα υπόλοιπα συστατικά του σκυροδέματος καθορίζοντας την τελική ποιότητα του. Τα σημαντικότερα χαρακτηριστικά των αδρανών υλικών σκυροδέματος, τα οποία εντοπίστηκε ότι είναι εφικτό να επηρεάσουν δυσμενώς την τελική μηχανική αντοχή του προϊόντος εντοπίστηκαν να είναι η επιφανειακή υφή τους (μικροανάγλυφο), οι φυσικές τους ιδιότητες, η ύπαρξη αργιλικών διογκούμενων ορυκτών στη δομή τους καθώς και η μηχανική τους αντοχή. Επιπροσθέτως, στα πλαίσια της παρούσας μελέτης ακολουθώντας τις αρχές τις κυκλικής οικονομίας και της αειφορίας επαναχρησιμοποιήθηκαν οι ορυκτές πρώτες ύλες όπου αξιολογήθηκαν ως αδρανή υλικά και σκυροδέματα για την επίλυση ενός μείζονος σημασίας περιβαλλοντικού προβλήματος. Το περιβαλλοντικό πρόβλημα που μελετήθηκε εστιάζεται στην όξινη απορροή του τέλματος στη βάση της ανοικτής εκσκαφής του παλαιού μεταλλείου του Αγίου Φιλλίπου Κίρκης (17 km ΒΒΔ της Αλεξανδρούπολης) το οποίο τροφοδοτείται συνεχώς από μετεωρικά νερά τα οποία οδηγούνται στο τέλμα αφού πρώτα έχουν αποπλύνει οξειδωμένα μεταλλικά ορυκτά και ιδιαίτερα θειούχα της ανοικτής εκσκαφής. Η οξείδωση των θειούχων μεταλλευμάτων της εξεταζόμενης περιοχής λαμβάνει χώρα δια μέσου μιας σειράς αντιδράσεων που περιλαμβάνουν άμεσους και έμμεσους και βακτηριδιακά ελεγχόμενους μηχανισμούς. Μερικές αντιδράσεις οξείδωσης έχουν ως αποτέλεσμα την παραγωγή άμεσης οξύτητας, ενώ άλλες προκαλούν διαλυτοποίηση και κινητοποίηση των βαρέων μετάλλων. Στα πλαίσια της παρούσας μελέτης με σκοπό την πειραματική μελέτη εξυγίανσης του αναφερθέντος φαινομένου κατασκευάστηκαν στατικές αλλά και πρότυπες ηλεκτροκίνητες συνεχούς ροής διατάξεις χρησιμοποιώντας πολυορυκτολογικά φίλτρα γραμμής. Ιδιαιτέρως αποδοτικά αναφορικά με την εξυγίανση του pH αλλά και την απομάκρυνση ή σημαντική μείωση συγκεντρώσεων βαρέων μετάλλων όπως Fe, Cu, Pd, Zn παρουσιάστηκε να επέδρασε η επαναχρησιμοποίηση των μαγνησίτη, σερπεντινίτη, ανδεσίτη, καθώς και η χρήση της τύρφης και του βιοεξανθρακώματος εντός των πειραματικών διατάξεων

Geochemical Occurrence of Rare Earth Elements in Mining Waste and Mine Water: A Review

Μining waste, processing by-products and mine water discharges pose a serious threat to the environment as in many cases they contain high concentrations of toxic substances. However, they may also be valuable resources. The main target of the current review is the comparative study of the occurrence of rare earth elements (REE) in mining waste and mine water discharges produced from the exploitation of coal, bauxite, phosphate rock and other ore deposits. Coal combustion ashes, bauxite residue and phosphogypsum present high percentages of critical REEs (up to 41% of the total REE content) with ΣREY content ranging from 77 to 1957.7 ppm. The total REE concentrations in mine discharges from different coal and ore mining areas around the globe are also characterised by a high range of concentrations from 0.25 to 9.8 ppm and from 1.6 to 24.8 ppm, respectively. Acid mine discharges and their associated natural and treatment precipitates seem to be also promising sources of REE if their extraction is coupled with the simultaneous removal of toxic pollutants

New Occurrence of Pyroxenites in the Veria-Naousa Ophiolite (North Greece): Implications on Their Origin and Petrogenetic Evolution

The Veria-Naousa ophiolite represents a dismembered unit in north Greece, which includes variably serpentinised lherzolite and harzburgite, locally intruded by a sparse network of dykes or thin layers of websterite and olivine-orthopyroxenite composition. The websterite and the olivine-orthopyroxenite show abundant petrographic and geochemical evidence (relic olivines with mantle affinities, Cr-rich spinels, low Al2O3, depletions in incompatible elements, and concave upwards rare earth element patterns) that they comprise replacive bodies from refractory subarc mantle precursors. The occurrence of these pyroxenites in dykes implies that channelled percolation of melts account for their replacive character. High CaO/Al2O3, low Zr and crystallisation of diopside suggest that a melt of ankaramitic/carbonatitic composition percolated in lherzolite replacing porphyroclastic olivine and forming the pyroxenes in the websterite. At a shallower level, harburgites were impregnated by boninitic melts (inferred by U-shape rare earth element patterns and very rich in Cr spinels) triggering the replacement of porphyroclastic olivine by orthopyroxene for the formation of olivine-orthopyroxenite. These peritectic replacements of olivine commonly occur in a mantle wedge regime. The peculiar characteristics of the Veria-Naousa pyroxenites with LREE and compatible elements enrichments resemble the subarc pyroxenites of Cabo Ortegal implying a similar environment of formation. Whole-rock and mineralogical (spinel and clinopyroxene) compositions are also in favour of a backarc to arc environment. It is recommended that the evolution of the Veria-Naousa pyroxenites record the evolution of the subarc region and the opening of a backarc basin in a broad SSZ setting in the Axios Zone of eastern Greece

Mineralogical Evidence for Partial Melting and Melt-Rock Interaction Processes in the Mantle Peridotites of Edessa Ophiolite (North Greece)

The Edessa ophiolite complex of northern Greece consists of remnants of oceanic lithosphere emplaced during the Upper Jurassic-Lower Cretaceous onto the Palaeozoic-Mesozoic continental margin of Eurasia. This study presents new data on mineral compositions of mantle peridotites from this ophiolite, especially serpentinised harzburgite and minor lherzolite. Lherzolite formed by low to moderate degrees of partial melting and subsequent melt-rock reaction in an oceanic spreading setting. On the other hand, refractory harzburgite formed by high degrees of partial melting in a supra-subduction zone (SSZ) setting. These SSZ mantle peridotites contain Cr-rich spinel residual after partial melting of more fertile (abyssal) lherzolite with Al-rich spinel. Chromite with Cr# > 60 in harzburgite resulted from chemical modification of residual Cr-spinel and, along with the presence of euhedral chromite, is indicative of late melt-peridotite interaction in the mantle wedge. Mineral compositions suggest that the Edessa oceanic mantle evolved from a typical mid-ocean ridge (MOR) oceanic basin to the mantle wedge of a SSZ. This scenario explains the higher degrees of partial melting recorded in harzburgite, as well as the overprint of primary mineralogical characteristics in the Edessa peridotites

Evaluation of Cement Performance Using Industrial Byproducts Such as Nano MgO and Fly Ash from Greece

The need for environmentally friendly construction materials is growing more and more these days. This paper investigates byproducts from Greece, such as magnesite tailings from Evoia and fly ash from Kardia (Ptolemais), in order to evaluate their suitability as cement additives. For this purpose, the raw materials were tested and studied regarding their mineralogical and chemical components for their morphological characteristics. Different cement specimens of various mixtures of raw materials were produced and tested. These raw materials are considered suitable for cement additives. The effect of nano MgO content seems to have played a more critical role in the physicomechanical performance of produced cement compared to that of the fly ash content. Furthermore, more satisfactory results in the physicomechanical properties of the produced cement gave samples of group II containing 3–4% of nano MgO. Nano MgO content up to 4% seems to have negative influence on the compressive strength of the produced cement, simultaneously reducing its durability. The increase of nano MgO content leads to the increase of the expansion of the produced cement specimens. In the early stage, the expansion rate was intensively larger. With the consumption of nano MgO, the expansion in the later stage gradually slowed down and tended to stabilize

Petrographic Characteristics of Sandstones as a Basis to Evaluate Their Suitability in Construction and Energy Storage Applications. A Case Study from Klepa Nafpaktias (Central Western Greece)

This study investigates how the petrographic features of Klepa Nafpaktias sandstones affect their behavior in construction applications such as concrete, in environmental applications such as energy storage as well as whether they are suitable for the above uses. For achieving this goal, sandstones (ten samples) were collected in order to study their petrographic characteristics using petrographic microscope and GIS software, as well as their basic physical, mechanical and physicochemical properties were also examined. Concrete specimens (C25/30) were made according to international standards including the investigated aggregate rocks in various grain sizes. Various sandstones were tested and classified in three district groups according to their physicomechanical features as well as to their petrographic and microtopographic characteristics. Concrete strength’s results determined the samples into three groups which are in accordance with their initial classification which was relative to their grain size (coarse to fine-grained). As the grain size decreases their physicomechanical and physicochemical properties get better resulting in higher concrete strength values (25 to 32 MPa). Furthermore, the proposed ratio C/A (crystals/mm2) seems to influence the aggregate properties which constitute critical factors for the final concrete strength, presenting the more fine-grained sandstones as the most suitable for concrete aggregates. Concerning the use of Klepa Nafpaktias sandstones as potential energy reservoirs, the studied sandstones presented as suitable for CO2 storage according to their physicomechanical characteristics

Utilization of Industrial Ferronickel Slags as Recycled Concrete Aggregates

The scope of this study focuses on the use of two different types of industrial byproducts such as slags (FeNi and Electric Arc Furnace slag) combined with natural sand as concrete aggregates as well as the evaluation of their suitability on the final physicomechanical behavior of the produced concrete specimens. For this reason, twelve concrete specimens were prepared using variable concentrations of these slags which were compared to concrete specimens made by natural rocks as aggregates (limestones). The mineralogical, petrographic, chemical and morphological characteristics of these raw materials were related to the physicomechanical characteristics of the produced concrete specimens. Those concrete specimens containing aggregates of higher amount of Electric Arc Furnace slags seems to present better mechanical strength both in 7 and in 28 days of curing regarding the other mixtures and regarding the specimens made by natural rocks as aggregates (limestones). This is due to the mineralogical, textural and morphological characteristics of the tested slags, which lead to a better bonding between them and the cement paste making them at the same time a promising alternative in the production of green concrete for construction applications. The compact texture of slags is responsible for the stronger bonding with the aggregates in relation to the unevenly distributed porosity of the natural aggregates. Wüstite presents negative effect on the final mechanical strength of concrete specimens which is documented both by the microscope images and by the three-dimensional study of the produced concretes

Does the Methylene Blue Test Give Equally Satisfactory Results in All Studied Igneous Rocks Relative to the Identification of Swelling Clay Minerals?

The presence or the absence of swelling clay minerals in rocks, which are used in various construction applications, constitutes a determinant factor for their strength, and consequently, in their general behavior in various construction applications, as they have the ability to swell up to 400 times of their usual volume, causing failures to any application in which they participate. The aim of this study is to respond to the question of whether the empirical method of methylene blue yields equally safe and correct results in different types of igneous rocks and if not, which is the determining factor affecting the results. The answer to this complex question is feasible by investigating the microscopic structure and the mineralogy of the studied rocks, and particularly, using the content of specific phyllosilicate minerals which may be related or not with the methylene blue values. According to the results, the methylene blue test seems to work correctly for the intermediate (Group I) and mafic (Group II) examined rocks, but it seems to be wrong for the highly serpentinized ultramafic rocks (up to 70% of serpentine) (Group III)