Search

This study focuses on the use of petrology as a useful tool in construction applications (i.e., concrete). More specifically, this study investigates how the petrogenetic characteristics of ultramafic rocks derived from ophiolite complexes (Veria–Naousa, Gerania) can act as a key tool for the prediction of the final behaviour of ultramafic aggregates as concrete aggregates. For this reason, their petrographic, chemical and mineralogical characteristics were examined and correlated with their engineering properties for evaluating their suitability as concrete aggregates. This study had come up, for the first time, that the genesis environment of the ultramafic rocks is the determinant factor for their physico-mechanical characteristics. Their suitability is relevant to the impact of their mineralogical and structural characteristics both from the two different ophiolite complexes (Veria–Naousa and Gerania). Except serpentinization, the basic alteration process-index of ultramafic rocks, there are also other chemical indices which can be used for ultramafic rocks that may determine their properties. In this context the term 'fertility rate' (FR) was introduced which may characterize ultramafic rocks as fertile or not. Furthermore, the Ultramafic Rock Health Index (U.R.H.I.) as well as the Normalized U.R.H.I. (U.R.H.I.N) was also introduced and correlated with the engineering properties of the investigated aggregate rocks. The last index aims to assess and quantify the overall health conditions, encompassing the two major modifying factors that include removal of primary mineral phases, as well as the extent of serpentinization. The main conclusion of this paper is that the genesis environment of the ultramafic rocks is the critical factor that determines their mineralogical, petrographic and chemical characteristics which consequently determines the basic engineering properties of rocks that determine their suitability or not as concrete aggregates. [ABSTRACT FROM AUTHOR]

We investigate with this study the effectiveness of mechanically activated serpentinite in capturing Cu (II) from the multi-constituent acidic wastewater of the pit lakes of the Agios Philippos mine (Greece), proposing specific areas with serpentinites suitable for such environmental applications. For this purpose ultramafic rock samples that are characterized by variable degrees of serpentinization from ophiolitic outcrops exposed in the regions of Veria-Naousa and Edessa have been examined regarding their capacity to remove the toxic load of Cu (II) from wastewater after having been mechanically activated through a Los Angeles (LA) machine (500, 1000 and 1500 revolutions). The more serpentinized and mechanically activated samples, as they have been characterized after a combination of various mineralogical, petrographic, geochemical analyses as well as after different stresses of abrasion and attrition, seem to be more effective in Cu removal than the less serpentinized ones. Selective removal of Cu (II) in the wroewolfeite phase was obtained by using the mechanically activated highly serpentinized ultramafic rocks. Furthermore, areas with highly serpentinized ultramafic rocks defined after petrographic mapping, using GIS method, which can potentially be used as filters for the effective Cu (II) removal from industrial wastewater are suggested. [ABSTRACT FROM AUTHOR]

This study examines how the chemical composition of ultramafic and mafic rocks effects their physicomechanical properties and therefore how influences the concrete strength of the produced concrete specimens. For this scope, ultramafic (Group I) and mafic rocks (Group II) derived from the Veria–Naousa and Edessa ophiolite complexes (Greece) were selected in order to identify their chemical composition and their engineering properties according to international standards. Additionally, representative rocks were used as concrete aggregates in order to produce concrete specimens, whereas their mechanical strength was calculated. A geochemical index (Ga) was proposed and correlated with the engineering properties of the examined rocks as well as with the widely used alteration degree LOI (loss on ignition). Correlation diagrams between engineering properties and the proposed geochemical index (Ga) have showed that these properties were strongly influenced by the alteration processes expressed via Ga index. More particularly, mainly serpentine in ultramafic and chlorite in mafic rocks, minerals indicators for the alteration of ultramafic and mafic rocks, respectively, seem to determine their engineering properties. Concerning the mechanical strength of the produced concrete specimens, the results have showed that the increasing values of Ga index negatively effect concrete strength. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]