Wet packing of blended fine and coarse aggregate

Kwan, A.K.H.; Li, L.G.; Fung, Winston Wing‐Shing

doi:10.1617/s11527-011-9800-3

Cited by 48 publications

(16 citation statements)

References 21 publications

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“…Furthermore, the final optimum MFF of 39.2% is smaller than the MFF of 44% measured by the conventional dry packing density method. This phenomenon resembles the wet packing density method; in fact, the MFF calculated by the wet density method is around 5% smaller than the one measured by the dry density method [25]. Therefore, the concrete mix design obtained from the modified packing density method can produce a similar effect of the wet packing density method and is more realistic.…”

Section: Designmentioning

confidence: 72%

“…Since there is not much powder in the coarse aggregate, the proportion of the coarse aggregate can still be determined by the conventional packing density method. As the packing density correlates positively with the bulk density [25], the bulk density is measured for the proportion selection in place of the packing density from now on.…”

Section: Modified Packing Density Methods For the Crfa Concrete MIX Dementioning

confidence: 99%

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Concrete Mix Design for Completely Recycled Fine Aggregate by Modified Packing Density Method

Yang

Chen

et al. 2020

Materials

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The undesirable properties of conventional recycled fine aggregate (RFA) often limit its application in the construction industry. To overcome this challenge, a method for preparing completely recycled fine aggregate (CRFA), which crushes all concrete waste only into fine aggregate, was proposed. The obtained CRFA had high apparent density, and its water absorption was lower than that of the conventional RFA. To take advantage of the CRFA, this paper introduced the modified packing density method for the CRFA concrete mix design. The modified packing density method took account of the powder with a particle size of smaller than 75 μm in the CRFA and balanced both the void ratio and the specific surface area of the aggregate system. Concrete (grade C55) was prepared using the CRFA to validate the feasibility of the proposed method. The unit price of the prepared CRFA concrete was around 12.7% lower than that of the natural aggregate concrete. Additionally, the proposed procedure for the concrete mixture design could recycle all concrete waste into the new concrete and replace all the natural fine aggregate in the concrete mixture.

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Section: Designmentioning

confidence: 72%

Section: Modified Packing Density Methods For the Crfa Concrete MIX Dementioning

confidence: 99%

Concrete Mix Design for Completely Recycled Fine Aggregate by Modified Packing Density Method

Yang

Chen

et al. 2020

Materials

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“…The other samples can be explained by the Krieger-Dougherty equation, which is also valid for the mixed sample case. Measurement of wet packing, contrary to the dry packing adopted in this study, is expected to decrease the difference because the hydrodynamic properties of grains are not consistent when they are floating in a suspended medium (Kwan et al 2012). Additionally, as a possible factor, the chemical admixtures used in this research are affected by changing packing density under wet conditions, which induces errors between predicted viscosity and dry packing density.…”

Section: Rheology Of the Mortar Samplesmentioning

confidence: 88%

Critical Grain Size of Fine Aggregates in the View of the Rheology of Mortar

Han

Kim

Lee

et al. 2017

Int J Concr Struct Mater

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The aim of this research was to investigate the validity of the Krieger-Dougherty model as a quantitative model to predict the viscosity of mortar depending on various aggregate sizes. The Krieger-Dougherty model reportedly predicted the viscosity of a suspension, which includes cement-based materials. Concrete or mortar incorporates natural resources, such as sand and gravel, referred to as aggregates, which can make up as much as 80% of the mixture by volume. Cement paste is a suspending medium at fresh state and then becomes a binder to link the aggregate after its hydration. Both the viscosity of the suspending medium and the characteristics of the aggregates, therefore, control the viscosity of the cement-based materials. In this research, various sizes and gradations of fine aggregate samples were prepared. Workability and rheological properties were measured using fresh-state mortar samples and incorporating the various-sized fine aggregates. Yield stress and viscosity measurements were obtained by using a rheometer. Based on the packing density of each fine aggregate sample, the viscosity of the mortar was predicted with the Krieger-Dougherty model. In addition, further adjustments were made to determine the water absorption of fine aggregates and was transferred from successful experiment to simulation for more accurate prediction. It was also determined that both yield stress and viscosity increase when the fine aggregate mean size decreases throughout the mix. However, when the mean size of the fine aggregates is bigger than 0.7 mm, the yield stress is not affected by the size of the fine aggregate. Additionally, if aggregate grains get smaller up to 0.3 mm, their water absorption is critical to the rheological behavior.

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“…The wet packing test developed by the authors' research team [35] was used to measure the packing density of the aggregate particles. Basically, the aggregate was added with water and the bulk density of the water-solid mixture measured, from which the solid concentration of the aggregate particles was calculated.…”

Section: Aggregate Packing Density Testsmentioning

confidence: 99%