Reuse of By-Products from Ready-Mixed Concrete Plants for the Production of Cement Mortars

This study was motivated by the necessity to recycle sludge water resulting from washing out concrete mixing trucks - a problem of both environmental and economic importance for the ready-mixed concrete industry. Sludge water from ready-mixed concrete plants as well as dry sludge, which is derived from the settling of the water, are hazardous for disposal due to their high pH value (pH>11.5). In this work, cement mortars were composed using either sludge water after various treatment, or dry sludge in several ratios. The cement mortars were tested for their workability and strength development. The purpose of this experimental design was to prove that sludge water, as well as sludge in a wet or dry form, can be used in the production of mortars without degrading any of their properties

Use of Steel Slag as Coarse Aggregate for the Production of Pervious Concrete

Pervious concrete is a type of concrete with significantly increased water permeability, ensuring increased rates of drainage of rainfall. The high porosity is achieved by removing a large percentage of fine aggregates from the mix. The present paper is an approach for the addition of steel slag as a substitute for coarse aggregates in pervious concrete. More specifically, three types of aggregates have been used: steel slag, construction and demolition wastes and conventional limestone aggregates. The produced pervious concretes are compared for their properties, such as water permeability, compressive strength and abrasion behaviour. Also this paper contains the study of the porosity analysis of these pervious concrete mix designs by using porosity profiles produced from X-ray CT Scanning. According to the results of this paper, it is observed that the incorporation of industry by-products or of Construction and Demolition (C&D) wastes leads to better abrasion behaviour, and to the increase, in some cases, of the compressive strength and of the water permeability

A case study of lime`s behavior during slaking with different set of natural water: implications for industrial water treatment technologies for light brackish waters

Two samples were collected from different quarries from Greece; one sample is characterized as calcitic limestone and the other as dolomitic limestone. The samples were calcined at 1050 0C. We investigated the effective role of the water anions on the reactivity and slaking rate on the basis of laboratory-produced quicklime. The ultimate scope of the present work is to place constraints on the brackish-water treatment processes as potential guidelines, marking the cost-benefits of pointless investments

Assessment of the quality of calcination of marbles from Thassos Island using Raman spectroscopy and X-Ray Diffraction

The degree of calcination of a dolomitic and a calcitic marble from Thassos Island, was investigated, by combining both Raman spectroscopy (RS) and X-Ray diffraction (XRD) techniques. The samples were prepared in isometric 2 cm cubes and calcined at three different temperatures, 900, 1050 and 1200 0C for 2 hours in order to produce quick lime. RS was applied at the lime sample's surface and inner (near core) part after gently crushing. XRD was applied on the bulk rock specimens in order to verify the transformation process during heating of the raw material. Quality control of the applied calcination procedure is provided through the hydration of quick lime. The rise in solution temperature suggests the chemical "reactivity" of the produced slaked lime. Raman and XRD results revealed the presence of unburned quantities of calcite and dolomite on samples that were calcined at 900 0C. Furthermore, temperatures of 1050 and 1200 0C have shown comparable mineralogical features signifying evenly the conversion of carbonate minerals to their oxide equivalents, proving the completion of the calcination process. Finally, reactivity tests showed that the highest reactivity value of the produced quicklime, for both marbles is observed at the temperature of 1050 0C

Political Development and Social Organization in Southern Europe

This thesis examines several specific issues pertaining to the relationship between State and Society in the countries of Southern Europe during the 19th and early 20th centuries. The analysis to be undertaken attempts to identify the essential elements of the interconnection between delayed capitalist economic development and socio-political transformation within the specific social and economic context found in Spain, Portugal, Italy, and Greece during the cited period. It is, thus, inherently implied that there exists a common pattern of diachronic change in these four social formations regarding the issues in question. The argument shows that, despite the marked differences, there indeed existed a pattern of cross-national social structural regularities (constants) which, in combination with the influences exerted because of the region's geopolitical location and its position in the international division of labor, determined the outcome of the internal struggle: in the individual countries on the political level, producing a uniform mode of power distribution and political determination by the end of the era examined. Methodology includes investigation into the existing distribution of power and social relationships of production, the influences and effects of the already advanced capitalist nations, and the growing capitalistically minded and oriented socioeconomic forces within these societies and their struggles to overcome existing barriers to transforming the whole system