Sidney Diamond
Purdue University
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Cement and Concrete Research | 2000
Sidney Diamond
Abstract The conditions that must be met for mercury intrusion porosimetry (MIP) measurements to provide valid estimates of the pore size distribution of porous solids are reviewed. Evidence is presented indicating that these conditions are not satisfied in cement-based systems. In cement systems, nearly all of the mercury intrusion is held up until pressure corresponding to the threshold diameter is reached; subsequently, large and small pores are filled indiscriminately. Air voids, in sizes up to several hundred micrometers, are present in most pastes in substantial volume, unless the pastes were mixed under vacuum; these air voids are also not intruded until the threshold pressure is reached, and are recorded as fine (ca. 0.1 μm) pores. It is concluded that MIP measurements are useful only to provide threshold diameters and intrudable pore space measurements, which can serve as comparative indices for the connectivity and capacity of the pore systems in hydrated cements. MIP measurements should be abandoned as measures of the actual pore sizes present.
Cement and Concrete Research | 1981
R.S. Barneyback; Sidney Diamond
Abstract A device is described that has been used for several years for expression pf pore solution from hardened portland cement pastes and mortars. Particulars with respect to the design, fabrication, and operation of such equipment are given, and methods for the analysis of the resulting small volumes of pore solutions are briefly discussed. It is believed that the compositions of the pore solutions obtained are representative of that of the bulk of the pore solution within the paste or mortar from which the solutions have been obtained.
Clays and Clay Minerals | 1970
Sidney Diamond
A knowledge of the distribution of pore sizes in clay and soil bodies is a useful element in the microstructural characterization of such materials. Pore-size distributions and total porosity of a number of reference clays, naturally-occurring subsoils, and commercial clay samples prepared in various ways were determined by mercury porosimetry. The range of equivalent pore diameter explored covered almost five orders of magnitude, from several hundred microns down to approximately 150 A. The method and its assumptions are critically evaluated, and measurements of the contact angle of mercury on clays yield values of 139° for montmorillonite and 147° for kaolinite and illite clays. The extent of shrinkage on oven-drying prior to mercury intrusion is assessed in each case and found to vary from insignificant to as much as 30 per cent of the pore space, depending on microstructural state and degree of initial saturation. The development of techniques for water removal which do not involve change in pore structure is explored. Some preliminary results for structurally weak saturated clays suggest that critical-region drying and perhaps freeze-drying procedures may be practical.RésuméLa connaissance de la distribution des dimensions des pores dans l’argile et les constituants du sol, est un élément utile dans la caractérisation microstructurale de tels matériaux. Les distributions de la dimension des pores et la porosité totale d’un certain nombre d’argiles de référence, se produisant naturellement dans les sous-sols, et les échantillons d’argile commerciaux préparés de différentes manières, ont été détermines par la porosimétrie du mercure. L’étendue du diamètre équivalent du pore exploré, couvrait presque cinq ordres de grandeur, variant de plusieurs centaines de microns pour atteindre approxativement 150 A. La méthode et ses hypothèses sont évaluées d’une façon critique, et les mesures de l’angle de contact de mercure sur les argiles fournissent des valeurs de 139° pour le montmorillonite et 147° pour la kaolinite et les argiles illite. Le degré de retrait par séchage au four préalablement à l’injection de mercure est évalué dans chaque cas et on s’aperçoit qu’il varie d’une valeur insignifiante pour atteindre un taux de 30 pour cent de l’espace du pore, cela dépend de l’état microstructural et du degré de saturation initial. Le développement des techniques pour l’élimination d’eau qui n’implique pas de modifications dans la structure du pore est exploré. Certains résultats préliminaires pour les argiles saturés, structurellement faibles, suggèrent que le séchage de la région critique et peut-être les méthodes de séchage par congélation, peuvent être pratiqués.KurzreferatEine Kenntnis der Verteilung der Porengrössen in Tonen und Erdböden ist ein wichtiges Element in der mikrostrukturellen Charakterisierung solcher Materiale. Die Porengrössenverteilungen und die Gesamtporosität einer Anzahl von Kontrolltonen, natürlich vorkommender Untergrunde und auf verschiedene Weise bereiteter, handelsmässiger Tonproben wurden mittels Quecksilber-Porosimetrie bestimmt. Der Bereich untersuchter Porendurchmesser umfasste beinahe fünf Grössenordnungen, angefangen von einigen Hundert Mikrons bis hinunter zu etwa 150 A. Dieses Verfahren und seine Voraussetzungen werden kritisch beurteilt, und Messungen des Kontaktwinkels des Quecksilbers an Tonen ergaben Werte von 139° für Montmorillonit und 147° für Kaolinit und Illit Tone. Das Ausmass der Schrumpfung durch Ofentrocknung vor dem Eindringen des Quecksilbers wurde jeweils eingeschätzt, und es wurde festgestellt, dass die Variation, je nach dem mikrostrukturellen Zustand und dem Masse an anfänglicher Sättigung, sich von unbedeutenden Werten bis hinauf zu 30 Prozent des Porenraumes bewegten. Die Entwicklung von Methoden für die Entfernung von Wasser ohne Veränderung der Porenstruktur wird erörtert. Vorläufige Resultate mit strukturell schwachen, gesättigten Tonen deuten darauf hin, dass Trocknung im kritischen Bereich und vielleicht Friertrocknungsverfahren von praktischer Bedeutung sein könnten.РезюмеРаспределение размеров пор в глине и почвах является для этих материалов важным элементом их микроструктурной характеристики. Распределение размеров пор и общая пористость для стандартных глин и подпочвенных образцов, а также для различно приготовленных образцов коммерческих глин были определены с помощью ртутного метода. Интервал найденных размеров эквивалентного диаметра пор покрывает почти пять порядков величины, от нескольких сотен микрон до примерно 150 А. Сам метод и использованные в нем допущения критически оценены, а измерения контактного угла ртути на глинах дали значения 139° для монтмориллонитовых и 147° для каолинитовых и гидрослюдистых глин. В каждом случае оценена степень сжатия при высушивании в печах до внедрения ртути и найдено, что в зависимости от микроструктурного состояния и степени первоначального насыщения она изменяется от незначительной до 30% объема пор. Рассмотрены возможности развития методов удаления воды без изменения пористой структуры. Некоторые предварительные данные для структурно слабо насыщенных глин указывают на практическую значимость высушивания в критической области, а также, возможно, и высушивания при замораживании.
Cement and Concrete Research | 1981
Sidney Diamond
Abstract The influence of two Danish flyashes on alkali contents and other characteristics of cement paste pore solutions was investigated by preparing pastes with 30 percent replacement of cement with flyash, hydrating for up to six months, and expressing and analyzing the resulting pore solutions. Reference cement pastes (without flyash) were found to retain about 80 percent of the total potassium and about 60 percent of the total sodium of the cement in solution indefinitely, leading to solution concentrations of about 0.6M in combined alkalies. The alkali contents of the flyashes used were substantial (2.4 and 3.3 percent Na2O equivalent), and some of this is “available” as measured by standard tests. Despite this, neither flyash was found to contribute to the alkali content of the pore solutions. One was essentially inert to alkalies, the other extracted a small proportion of alkalies from the pore solutions.
Archive | 2014
Arnon Bentur; Sidney Diamond; Neal S. Berke
Introduction. Mechanisms of Steel Corrosion. Relations Between Corrosion and the Structure and Properties of Concrete. Corrosion Measurements. Corrosion Damage. Corrosion Measurements. Corrosion Control. Specificaitons and Design. Repair and Rehabilitation. Index.
Cement & Concrete Composites | 1996
Sidney Diamond
Abstract The scope of the delayed ettringite formation (DEF) problem is reviewed. Based on the experience of the writer and others, DEF is to be expected in both steam cured and non-steam cured concrete. The microstructural details appear identical. The common association with alkalisilica reactions is explored, and explained in terms of both prior cracking providing space for ettringite and in terms of the reduction in alkali hydroxide concentration in the pore solution attendant on ASR. The controversy concerning basic DEF mechanism between proponents of ‘homogenous paste expansion’ and ‘crystal pressure’ is explored. In the writers opinion the microstructural evidence is not compatible with homogeneous expansion, but is a distinct consequence of crystal pressure developed by ettringite. The thermodynamic analysis that limits expansive pressure in terms of the degree of supersaturation that can be supported may be applicable to ettringite in air voids, but is inapplicable to ettringite in cracks. Fracture mechanics considerations predict local stress concentrations at the crack tips that are many times those that can be generated in open spaces. An apparent example of such effects in opening up space between mica lamellae in steam cured concrete by ettringite deposition is provided.
Cement and Concrete Research | 1978
B.D. Barnes; Sidney Diamond; William L. Dolch
Abstract The morphology of the contact zone developed between Portland cement paste and glass slide “aggregates” has been explored using SEM and other techniques. A duplex film of about 1 μm total thickness is rapidly deposited on the glass surface. This is a continuous film of Ca(OH) 2 overlain by a parallel array of rod-shaped CSH gel particles projecting normal to the interface. The nearby cement paste exhibits high porosity, but after a few days becomes partly filled with a secondary deposit of stacked platelets of relatively pure Ca(OH) 2 . Cement particles near the interface hydrate in a peculiar manner. A hydration product shell is quickly formed, but the encapsulated cement particles dissolve away to leave partly or completely empty shells. This behavior occurs with various Portland cement types and presumably occurs near aggregate surfaces in concrete.
Cement and Concrete Research | 1983
Sidney Diamond
Abstract A suite of 16 American flyashes ranging in analytical CaO content from less than 2% to approximately 27% was subjected to x-ray diffraction and the position of the glass diffraction maximum determined. Flyashes of analytical CaO content of up to about 20% showed maxima indicative of siliceous glass. Within this range the 20 angular position of the maximum was found to increase linearly with CaO content, suggesting progressive modification of the siliceous glass structure with increasing calcium content. Flyashes of analytical CaO content higher than about 20% showed a glass diffraction maximum at a constant and much higher 20 angle, indicative of calcium aluminate glass structural type. The latter glass may be significantly more reactive in concrete.
Cement and Concrete Research | 1999
Sidney Diamond
Aspects of the pore structure of conventional concrete are reviewed. The appearance and distribution of pores are illustrated in the context of the microstructure of normal concretes as viewed in backscatter mode scanning electron microscopy. A significant portion of at least the larger pores found in concrete is considered to be derived from the hollow shell (Hadley grain) hydration mechanism. These pores therefore do not represent remnants of the original space between cement grains, the accepted concept of the origin of capillary pores. A brief review of the characteristics of surface fractals is provided and experiments are described, indicating that the surfaces constituting the boundaries of at least the larger pores in concrete are fractal in nature, at least over a limited range of self-similarity. It appears that the characteristic fractal dimension describing the pore surfaces is almost constant, regardless of age, water:cement ratio, or most other variables.
Cement and Concrete Research | 1971
Sidney Diamond
Abstract A comparison of pore-size distributions from mercury porosimetry and from capillary condensation measurements reveals discrepancies between the results of the two types of measurement for hydrated cement pastes. The mercury intrusion data indicate considerably coarser size distributions with mean diameters of the order of several hundred A. The capillary condensation data yield mean pore diameters between 50 and 100 A, and indicate that most of the space tallied is in pores of diameters less than 100A. Evidence derived from other techniques supports the presence of considerable pore volume in the range of diameters of several hundred to some thousands of A, which is consistent with the mercury porosimetry results.