Effects of particle packing density on the stability and rheology of self-consolidating concrete containing mineral admixtures

2014 ◽  
Vol 53 ◽  
pp. 102-109 ◽  
Author(s):  
Parviz Ghoddousi ◽  
Ali Akbar Shirzadi Javid ◽  
Jafar Sobhani
Keyword(s):  
Packing Density ◽  
Particle Packing ◽  
Mineral Admixtures ◽  
Self Consolidating Concrete ◽  
The Stability

The influence of particle packing density on wood combustion in a fixed bed under oxy-fuel conditions

Energy ◽  
2020 ◽  
Vol 194 ◽  
pp. 116863
Author(s):  
J.K. Tanui ◽  
P.N. Kioni ◽  
T. Mirre ◽  
M. Nowitzki ◽  
N.W. Karuri
Keyword(s):  
Packing Density ◽  
Fixed Bed ◽  
Particle Packing ◽  
Wood Combustion

scholarly journals Determination of the optimal replacement content of Portland cement by stone powder using particle packing methods and analysis of the influence of the excess water on the consistency of pastes

2019 ◽  
Vol 12 (2) ◽  
pp. 210-232 ◽  
Author(s):  
H. F. CAMPOS ◽  
T. M. S. ROCHA ◽  
G. C. REUS ◽  
N. S. KLEIN ◽  
J. MARQUES FILHO
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Packing Density ◽  
Particle Packing ◽  
Attractive Alternative ◽  
Excess Water ◽  
Stone Dust ◽  
Powder Content ◽  
Substitution Content

Abstract Cement is considered the basic component with the highest environmental impact in construction, in terms of CO2 emissions. As for the aggregates, the process of comminution of rocks, in addition to artificial sand, generates stone powder that ends up being stored outdoors, generating environmental damages. Thus, the replacement of cement by stone powder appears as an attractive alternative towards the sustainable concretes. In this context, the objective of this paper is to determine the maximum packing density in Portland cement, silica fume and stone dust pastes, to determine the optimal cement substitution content for the stone powder. In addition, it is intended to verify the influence of excess water on the consistency of the mixtures produced. The substitution was done in contents equal to 0%, 7%, 14% and 21% by volume and, for each content, the packing density was determined analytically by CPM model and combinations were reproduced experimentally. Excess water was checked by the mini Kantro cone test. The results showed that the higher cement substitution content of the stone powder obtained the higher packing density, experimental and analytical, and the higher workability, allowing economic and environmental advantages. Analyzing each material, the stone powder resulted in the highest packing density and silica fume is the lowest one. Therefore, finer particles resulted in lower packaging densities, due to the greater specific surface area, which demands more water. The agglomeration resulted in more empty gaps between the grains. In addition, mixtures flowability increased with the increase of the stone powder content. As the excess water is responsible for mixture lubrication, a higher packing density for a given volume of water improves the flowability.

A state-of-the-art review on the stability of self-consolidating concrete

2021 ◽  
Vol 268 ◽  
pp. 121099
Author(s):  
Zedi Zhang ◽  
Jia Xiao ◽  
Qing Zhang ◽  
Kaidong Han ◽  
Jialei Wang ◽  
...  
Keyword(s):  
State Of The Art ◽  
Self Consolidating Concrete ◽  
The Stability

scholarly journals Thixotropic Behavior in Defining Particle Packing Density of Highly Filled AP/HTPB-Based Propellant

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1767
Author(s):  
Afni Restasari ◽  
Luthfia Hajar Abdillah ◽  
Retno Ardianingsih ◽  
Hamonangan Rekso Diputro Sitompul ◽  
Rika Suwana Budi ◽  
...  
Keyword(s):  
Packing Density ◽  
Relative Viscosity ◽  
Particle Packing ◽  
Peak Time ◽  
Curing Process ◽  
Stress Growth ◽  
Composite Solid Propellant ◽  
Thixotropic Behavior ◽  
Maximum Particle ◽  
Composite Solid

An alarming, asymmetric flame in rocket combustion originates from a composite solid propellant (CSP) containing defects. The defects are the result of a composition that exceeds the maximum particle packing density. Based on the structure analysis of CSP, the addition of plasticizer causes the correlation between the viscosity of CSP slurry and particle packing density to become uncertain. This work aims to investigate the influence of thixotropic behavior on the maximum particle packing density of CSP. A CSP with different thixotropic behavior was successfully produced using aluminum/plasticizer dioctyl adipate (DOA) of 12–24. During the curing process, viscosity and stress–growth were investigated. The structure of the CSP was defined using X-ray radiography. It is remarkably observed that the peak of thixotropy occurred at the 15th minute of the curing process. The particle packing density of CSP can be decisive for the relative viscosity at the peak time of thixotropic behavior. The CSP with the highest relative viscosity at the peak time was revealed to have voids in the upper part of the CSP. Thus, this parameter was proven to change the preceding parameter, viscosity that was measured at the end of mixing. Based on the stress–growth analysis, it is conceivable that the mechanism involves the time-dependent diffusion of DOA in weakening aluminum agglomerates.

scholarly journals Improving Recycled Aggregate Quality by Mechanical Pre-Processing

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4342
Author(s):  
Madumita Sadagopan ◽  
Katarina Malaga ◽  
Agnes Nagy
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Packing Density ◽  
Shape Index ◽  
Recycled Aggregate ◽  
Unit Weight ◽  
Void Content ◽  
Natural Aggregates ◽  
The Stability ◽  
Flakiness Index

Concrete with crushed concrete aggregates (CCA) shows lesser compressive strength than reference concrete with natural aggregates. The goal of this study is to improve the strength of structural concrete with 53% and 100% CCA replacements without increasing the cement content. Thus, improvements in CCA quality are induced by combining mechanical and pre-soaking pre-processing techniques. Mechanical pre-processing by rotating drum is separately pursued on fine and coarse CCA for 10 and 15 min respectively. Results show, adhered mortar content and CCA water absorption reduces as pre-processing duration increases. Pre-processing influences CCA particle grading, flakiness index, shape index, void-content, unit-weight and density, jointly seen as packing density, which increases with pre-processing duration. Water amount to pre-soak CCA before concrete mixing is stable despite grading modifications, due to reduced water absorption resulting from mechanical pre-processing. Compressive strength and workability for pre-processed CCA50 and CCA100 concrete are comparable to reference concrete and show similar trends of improvement with packing density. Packing density markedly shows the quality improvements induced by pre-processing on CCA, maybe considered as one of the quality assessment indexes for CCA. Packing density should be investigated for other recipes to see the stability of the trend with workability and compressive strength.

Strength and Durability Evaluation by DEM Approach of Green Concrete Based on Gap-Graded Cement Blending

2012 ◽  
Vol 450-451 ◽  
pp. 631-640 ◽  
Author(s):  
L.B Nghi Le ◽  
Piet Stroeven
Keyword(s):  
Portland Cement ◽  
Packing Density ◽  
High Performance ◽  
Cementitious Materials ◽  
Particle Packing ◽  
Mineral Admixture ◽  
Discrete Element Modeling ◽  
Pore Characteristics ◽  
Positive Effects ◽  
Concurrent Algorithm

This paper discusses the particle packing background of cementitious materials. On micro-level the Portland cement and eventually the mineral admixture grains can be considered packed in the watery environment. Particularly for (super) high performance materials, the packing density can be quite significant. An economic and due to fast computer developments reliable way to study packing of the binder, is by modern discrete element modeling (DEM) approach. In this paper use is made of a concurrent algorithm-based dynamic system, HADES. Hydration is simulated based on spherical grains. Thereupon strength can be studied on the basis of packing density. For durability issues, the complex and tortuous 3D pore structure has to be investigated. This paper uses for the assessment of pore characteristics the robotics-inspired DraMuTS system. Hydrated Portland cement is compared with gap-graded rice husk ash-(RHA)-blended (green) Portland cement. Experiments on gap-graded RHA-blended PC concrete are used as reference. Packing density is shown improved by gap-graded packing. What is more spectacular are the effects of gap-grading with RHA on the pore characteristics obtained on the DEM-produced virtual materials. This paper discusses the expected positive effects on transport-based durability issues due to gap-graded packing-induced changes in the pore system

scholarly journals Analysis of Cohesive Microsized Particle Packing Structure Using History-Dependent Contact Models

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Raihan Tayeb ◽  
Xin Dou ◽  
Yijin Mao ◽  
Yuwen Zhang
Keyword(s):  
Particle Size ◽  
Coordination Number ◽  
Gaussian Distribution ◽  
Packing Density ◽  
Mean Value ◽  
Distribution Functions ◽  
Particle Packing ◽  
Size Distributions ◽  
Packing Structure ◽  
Contact Models

Granular packing structures of cohesive microsized particles with different sizes and size distributions, including monosized, uniform, and Gaussian distribution, are investigated by using two different history dependent contact models with discrete element method (DEM). The simulation is carried out in the framework of liggghts, which is a DEM simulation package extended based on branch of granular package of widely used open-source code LAMMPS. Contact force caused by translation and rotation, frictional and damping forces due to collision with other particles or container boundaries, cohesive force, van der Waals force, and gravity is considered. The radial distribution functions (RDFs), force distributions, porosities, and coordination numbers under cohesive and noncohesive conditions are reported. The results indicate that particle size and size distributions have great influences on the packing density for particle packing under cohesive effect: particles with Gaussian distribution have the lowest packing density, followed by the particles with uniform distribution; the particles with monosized distribution have the highest packing density. It is also found that cohesive effect to the system does not significantly affect the coordination number that mainly depends on the particle size and size distribution. Although the magnitude of net force distribution is different, the results for porosity, coordination number, and mean value of magnitude of net force do not vary significantly between the two contact models.

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