Applying Theories of Particle Packing and Rheology to Concrete for Sustainable Development

Abstract

o r g a n i z a t i o n , t e c h n o l o g y a n d m a n a g e m e n t i n c o n s t r u c t i o n · a n i n t e r n a t i o n a l j o u r n a l · 5(2)2013 844Concrete is one of the most important construction materials. However, it is not so compatible with the demands of sustainable development because manufacturing of cement generates a large amount of carbon dioxide and therefore cement consumption produces a huge carbon footprint. Currently, the cement consumption is generally lowered by adding supplementary cementitious materials to replace part of the cement. Nonetheless, in order to maintain performance, there is a limit to such cement replacement by supplementary cementitious materials. To further reduce the cement consumption, the total cementitious materials content has to be reduced. This requires the packing density of the aggregate particles to be maximized so that the amount of voids in the bulk volume of aggregate to be filled with cement paste could be minimized and the surface area of the aggregate particles to be minimized so that the amount of cement paste needed to form paste films coating the surfaces of aggregate particle for rheological performance could be minimized. Such optimization is not straightforward and modern concrete science based on particuology is needed. Herein, a number of new theories regarding particle packing and rheology of concrete, which are transforming conventional concrete technology into modern concrete science, are presented. These theories would help to develop a more scientific and systematic concrete mix design method for the production of high-performance concrete with minimum cement consumption.

Unified Packing Model for Improved Prediction of Porosity and Hydraulic Conductivity of Binary Mixed Soils

“…For Equation (15), in case swelling index is not available, S = 10 can be used as an approximation for bentonite. The resultant porosity from the model above is expressed as function of volume fraction which can be converted to mass fraction through Equations (4) and (5) as done throughout this study.…”

“…The packing state (or porosity) of such sand-fines mixtures controls several important physical properties such as hydraulic conductivity and shear strength [1][2][3][4][5][6]. Binary mixed soils have received increasing attention due to their abundance as economically important sediment and for their applications as liners and cutoff walls [7][8][9], in filter design [10][11][12], and in concrete mixing [13][14][15]. Therefore, predicting porosity (or void ratio) and hydraulic conductivity of binary mixed soils can be important for various disciplines including environmental and water resources sciences as well as geotechnical and civil engineering [16][17][18][19][20][21].…”

Determinação da densidade de empacotamento de sistemas granulares compostos a partir da areia normal do IPT: comparação entre modelos de otimização de distribuição granulométrica e composições aleatórias

“…Uma forma de reduzir o consumo de cimento está atrelada a obter um esqueleto granular compacto, que apresente máxima densidade de empacotamento do agregado. Isso colabora para a redução do volume de pasta de cimento necessária para preencher os vazios existentes no esqueleto granular [3,4]. Assim, para se obter esqueletos granulares compactos é necessário fazer o uso de modelos de empacotamento de partículas que permitam estabelecer a proporção e tamanho adequados dos agregados, de modo a obter um conjunto com um baixo índice de vazios.…”

Avaliação da influência do empacotamento dos agregados na durabilidade de concretos através de ensaios não destrutivos: resistividade elétrica e propagação de ondas de ultrassom

“…O interesse pelo empacotamento de partículas aumentou nas diversas áreas de engenharia, uma vez que grande parte dos materiais industriais e naturais utilizados pelo homem é composto por partículas de diferentes formas e tamanhos [4].…”