Applications of the Rietveld method to quantify the crystalline phases of Portland cement clinker doped with nickel and chromium

The effects of chromium or nickel oxide additions on the composition of Portland clinker were investigated by X-ray powder diffraction associated with pattern analysis by the Rietveld method. The co-processing of industrial waste in Portland cement plants is an alternative solution to the problem of final disposal of hazardous waste. Industrial waste containing chromium or nickel is hazardous and is difficult to dispose of. It was observed that in concentrations up to 1% in mass, the chromium or nickel oxide additions do not cause significant alterations in Portland clinker composition. (C) 2008 International Centre for Diffraction Data.

Biocompatibility and setting time of CPM-MTA and white Portland cement clinker with or without calcium sulfate

To evaluate the biocompatibility and the setting time of Portland cement clinker with or without 2% or 5% calcium sulfate and MTA-CPM. Twenty-four mice (Rattus norvegicus) received subcutaneously polyethylene tubes filled with Portland cement clinker with or without 2% or 5% calcium sulfate and MTA. After 15, 30 and 60 days of implantation, the animals were killed and specimens were prepared for microscopic analysis. For evaluation of the setting time, each material was analyzed using Gilmore needles weighing 113.5 g and 456.5 g, according to the ASTM specification Number C266-08 guideline. Data were analyzed by ANOVA and Tukey's test for setting time and Kruskal-Wallis and Dunn test for biocompatibility at 5% significance level. Histologic observation showed no statistically significant difference of biocompatibility (p>0.05) among the materials in the subcutaneous tissues. For the setting time, clinker without calcium sulfate showed the shortest initial and final setting times (6.18 s/21.48 s), followed by clinker with 2% calcium sulfate (9.22 s/25.33 s), clinker with 5% calcium sulfate (10.06 s/42.46 s) and MTA (15.01 s/42.46 s). All the tested materials showed biocompatibility and the calcium sulfate absence shortened the initial and final setting times of the white Portland cement clinker

Studio degli acceleranti dell'idratazione del clinker e sintesi di composti alternativi da fonti rinnovabili

Il cemento è il materiale da edilizia più comune al mondo e le problematiche ambientali associate all’utilizzo ed al ciclo produttivo sono numerose (rilascio di gas serra, scelta delle materie prime, risparmio energetico) e fortemente impattanti. Tuttavia, nonostante la sua diffusione sia globale e le proprietà siano note da millenni vi sono ancora alcuni processi che non sono stati correttamente spiegati. In particolare non esiste una teoria unica e consolidata che descriva efficacemente la microstruttura delle fasi minerali del cemento che si sviluppano successivamente all'idratazione, e come esso di conseguenza interagisca con principi attivi, organici o inorganici, di cui è noto l’effetto accelerante sulla cinetica di indurimento. Questa tesi si pone l'obiettivo di condurre uno studio dell'idratazione del clinker finemente macinato (CFM - principale componente di molti cementi) focalizzato sull’interazione tra elementi chimici presenti nella matrice cementizia (Calcio, Ferro e Alluminio) ed additivi acceleranti (Trietanolammina, Triisopropanolammina). Il fenomeno è stato studiato tramite osservazione dell'andamento del rilascio dei suddetti ioni su cementi in via di idratazione e tramite utilizzo di tecniche di microscopia elettronica e di diffrazione di raggi X. L'analisi del rilascio di ioni, effettuata mediante spettroscopia ad assorbimento atomico, è stata condotta al fine di approfondire l'azione di trietanolammina e triisopropanolammina sulle dinamiche di idratazione dei CFM nelle fasi precoci di idratazione, al fine di confrontare queste dinamiche con processi che avvengono in fasi successive e che coinvolgono la formazione delle principali fasi amorfe e cristalline responsabili delle proprietà del materiale. Da indagini di diffrattometria e microscopia sono inoltre state estrapolate interessanti considerazioni circa le cinetiche che portano alla formazione delle fasi cristalline tipiche dell'idratazione del cemento (portlandite, ettringite) in presenza e assenza di additivi. Nel corso dello studio sono stati sintetizzati alcuni composti alternativi agli additivi commerciali, sviluppati a partire da building blocks provenienti da fonti rinnovabili, portando quindi l'attenzione sulla sostenibilità del processo di progettazione delle molecole, anche alla luce della degradazione in ambiente delle sostanze sintetizzate. Tali molecole sono attualmente in fase di test presso i laboratori di Italcementi (ITC Group).

Estudio de seguridad y salud para la construcción de una planta de molienda de clinker

El proyecto tiene por objeto establecer, en el marco de la Ley 31/1995, de 8 de noviembre, sobre prevención de riesgos laborales, y en su norma reglamentaria, el Real Decreto 1627/1997 de 24 de octubre, sobre disposiciones mínimas de seguridad y salud en las obras de construcción, la identificación y evaluación de riesgos de una planta industrial de molienda de clinker para fabricación de cemento, con objeto de determinar las medidas preventivas necesarias para garantizar las adecuadas condiciones de seguridad y salud de los trabajadores que intervengan en la construcción de la obra civil, y en los montajes eléctrico y mecánico. La metodología que se empleó para estimar los niveles de riesgo se basa en la conjunción de la probabilidad estimada y las consecuencias esperadas. Los resultados obtenidos a partir de los niveles de riesgo identificados demostraron que mediante la mejora de los controles existentes y la implantación de nuevas medidas de control, priorizando de forma que éstas siempre sean proporcionales al riesgo identificado y valorado, es posible garantizar los adecuados niveles de seguridad y salud durante la ejecución de la obra. ABSTRACT The main objective of this project is, in the frame of the Law 31/1995 of November 8th about prevention of labor risks and in its regulation norm, Royal Decree 1627/1997 of October 24th, about minimum dispositions of safety and health in the works of construction, the identification and evaluation of the risks involved in an industrial plant of grinding of clinker for cement manufacture in order to determine the preventive necessary measures to ensure the suitable conditions of safety and health of the workers who take part of civil works, and of electrical and mechanical erections. The methodology chosen to estimate the risk levels is based on the probability of happening together with the awaited consequences. The results obtained from the levels of risk identified demonstrated that by means of the improvement of the existing controls and the implementation of new control measures, determining priorities always proportionally to the identified and valued risk, it is possible to guarantee the suitable levels of safety and health during the execution of the works.

The expedition of Humphry Clinker /

Cohn, A.M. George Cruikshank,

The expedition of Humphry Clinker /

Added t. p., engraved: The expedition of Humphrey Clinker.

The expedition of Humphry Clinker /

Mode of access: Internet.

Miscellaneous works. Complete in one volume, containing Roderick Random, Peregrine Pickel, Ferdinand Count Fathom, Sir Launcelot, Greaves, Humphry Clinker, Adventures of an atom, Travels through France and Italy, Expedition against Carthagena [and] plays and poems.

Mode of access: Internet.

The expedition of Humphry Clinker /

"Memoir of Tobias Smollett," by Thomas Roscoe: p. 5-44.

Synthesis of active Belite-Alite-Ye'elimite clinker (BAY)

Ordinary Portland cement (OPC) is an environmentally contentious material, as for every ton of OPC produced, on average, 0.97 tons of CO2 are released. Ye'elimite-rich cements are considered as eco-cements because their manufacturing process releases less CO2 into the atmosphere than OPC; this is due to the low calcite demand. Belite-Alite-Ye’elimite (BAY) cements are promising eco-friendly building materials as OPC substitutes at a large scale. The reaction of alite and ye´elimite with water should develop cements with high mechanical strengths at early ages, while belite will contribute to later curing times. However, they develop lower mechanical strengths at early-medium ages than OPC. It is known that the presence of different polymorphs of ye'elimite and belite affects the hydration due to the different reactivity of those phases. Thus, a solution to this problem may be well the activation of BAY clinkers by preparing them with 'H-belite and pseudo-cubic-ye'elimite, jointly with alite. The aim of this work is the preparation and characterization of active-BAY clinkers which contain high percentages of coexisting 'H-belite and pseudo-cubic-ye'elimite, jointly with alite to develop, in a future step, comparable mechanical strengths to OPC. The parameters evolved in the preparation of the clinker have been optimized, including the selection of raw materials (mineralizers and activators) and clinkering conditions. Finally, the clinker was characterized through laboratory X-ray powder diffraction, in combination with the Rietveld methodology, and scanning electron microscopy.

Characterization of mixed waste of granite and LD slag

This study focuses on the technical feasibility of the utilization of waste from the cutting of granite to adjust the chemical composition of slag from steelworks LD, targeting the addition of clinker Portland cement. For this, chemical characterization of the waste, its mixture and fusion was performed, obtaining a CaO/SiO(2) relationship of around 0.9 to 1.2 for the steelworks slag. We selected samples of the waste, mixed, melted and cooled in water and in the oven. Samples cooled in water, after examining with X-ray difractrograms, had been predominantly amorphous. For samples cooled in the furnace, which had vitreous, there was the presence of mineralogical phases Akermanita and Gehlenita, which is considered as the ideal stage for the mineral water activity of the slag. The adjustment of the chemical composition of the slag from steel works by the addition of waste granite was efficient, transforming the waste into a product that is the same as blast furnace slag and can be used in the manufacture of cement.

CCT diagrams of tricalcium silicate decomposition

The mechanical properties of Portland cement are closely related to the chemical composition of the clinker and particularly to the concentration of tricalcium silicate, C3S. In the industrial production process, the clinker must be rapidly quenched, to avoid its decomposition into dicalcium silicate and lime and also to avoid the transformation from higher temperature phases to lower temperature phases. This study investigated the kinetics of thermal decomposition of the C3S. Samples of laboratory-made C3S were thermally treated under specific conditions to determine the continuous cooling transformation (CCT) diagram of the material. The CCT diagram of the C3S showed decomposition rates with values that were much higher than the values traditionally accepted in the literature.

Evaluation of the radiopacity of some commercial and experimental root-end filling materials

Objective. The aim of the present study was to evaluate the radiopacity of 5 root end filling materials (white MTA Angelus, MTA Bio, light-cured MTA, Sealepox RP, and Portland cement clinker with bismuth oxide and calcium sulfate). Method. Five specimens, 10 mm in diameter and 1 mm in thickness according to specification ISO 6876: 2001 were fabricated from each material and radiographed using Insigth occlusal films close to a graduated aluminum step-wedge (2 to 16 mm in thickness). Radiographs were digitized and compared to the aluminum step-wedge. The radiographic density data were converted into millimeters of aluminum (mm Al), using the Digora 1.51 software. Results were evaluated statistically using the analysis of variance (ANOVA) followed by Tukey test. The level of significance was set at 5% (P<.05%). Results. Radiopacity values ranged from 1.21 mm Al (light-cured MTA) to 6.45 mm Al (MTA Angelus). Comparison between materials showed significant difference (P<.05) between MTA Angelus and all other materials, between Sealepox RP and MTA Bio, and between light-cured MTA and Portland cement clinker. Light-cured MTA was significantly less radiopaque than all other materials. No significant difference (P>.05) was found between MTA Bio and Portland cement clinker. Conclusions. All retrograde filling materials evaluated showed greater radiopacity than dentin. All the materials, except light-cured MTA met the minimum radiopacity standards of 3 mm Al recognized by the ISO 6876: 2001 and ADA n.57. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: e35-e38)

Modelling cement grinding circuits

Modelling and simulation studies were carried out at 26 cement clinker grinding circuits including tube mills, air separators and high pressure grinding rolls in 8 plants. The results reported earlier have shown that tube mills can be modelled as several mills in series, and the internal partition in tube mills can be modelled as a screen which must retain coarse particles in the first compartment but not impede the flow of drying air. In this work the modelling has been extended to show that the Tromp curve which describes separator (classifier) performance can be modelled in terms of d(50)(corr), by-pass, the fish hook, and the sharpness of the curve. Also the high pressure grinding rolls model developed at the Julius Kruttschnitt Mineral Research Centre gives satisfactory predictions using a breakage function derived from impact and compressed bed tests. Simulation studies of a full plant incorporating a tube mill, HPGR and separators showed that the models could successfully predict the performance of the another mill working under different conditions. The simulation capability can therefore be used for process optimization and design. (C) 2001 Elsevier Science Ltd. All rights reserved.

Estudo das propriedades dos adjuvantes na compatibilidade/robustez cimento/adjuvante

A qualidade do betão pode ser controlada pelo comportamento da fluidez da pasta de cimento, o qual está relacionado com a dispersão das partículas de cimento. Um dos maiores avanços na tecnologia do betão tem sido o desenvolvimento de aditivos. Um destes tipos de aditivos, os Superplastificantes (SP), fornecem a possibilidade de se obter uma melhor dispersão das partículas de cimento, produzindo pastas com elevada fluidez. Com o desenvolvimento de betões de alta resistência e elevado desempenho, os superplastificantes tornaram-se indispensáveis. Os superplastificantes são adsorvidos nas partículas de cimento e esta adsorção depende da composição do clínquer do cimento e do tipo de SP utilizado. Com a difusão do emprego dos aditivos redutores de água, têm surgido vários problemas de compatibilidade cimento/adjuvante. Esta investigação dedicada aos superplastificantes, fortes redutores de água, visou estudar quais as propriedades que poderiam influenciar a sua compatibilidade/robustez com o cimento. Também se procurou ganhar experiência com as técnicas analíticas de caracterização de adjuvantes. Assim, utilizou-se um tipo de cimento e dois tipos de superplastificantes (poli(étercarboxilatos) e poli(naftalenossulfonatos)) disponíveis no mercado português. Mantendo a mesma razão água/cimento (A/C), pretendeu-se determinar a natureza química, grau de funcionalização, teor e tipo de contra-ião, teor de sulfatos/sulfonatos do adjuvante e o comportamento dos superplastificantes nas pastas cimentícias, de forma a poder determinar indicadores de compatibilidade entre cimentos e superplastificantes. Constatou-se que a natureza química, o grau de funcionalização e a quantidade consumida dos superplastificantes têm influência nas pastas. Os indicadores de compatibilidade por parte dos superplastificantes parecem estar relacionados com o comprimento da cadeia lateral de éter e com o rácio CO2R/CO2 -. A alteração do momento da adição do adjuvante tem influência na compatibilidade cimento/adjuvante, sendo benéfico para os poli(étercarboxilatos) e prejudicial para o poli(naftalenossulfonato).