scholarly journals Effects of packing density, excess water and solid surface area on flowability of cement paste

2008 ◽  
Vol 20 (1) ◽  
pp. 1-11 ◽  
Author(s):  
A. K. H. Kwan ◽  
H. H. C. Wong
Keyword(s):  
Surface Area ◽  
Cement Paste ◽  
Solid Surface ◽  
Packing Density ◽  
Excess Water ◽  
Density Excess

Improving Packing Density of Powder in Cement Paste for Production of High-Performance Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 1640-1647 ◽  
Author(s):  
Albert K.H. Kwan ◽  
J. J. Chen ◽  
Wilson W. S. Fung ◽  
Leo G. Li
Keyword(s):  
Silica Fume ◽  
Cement Paste ◽  
Packing Density ◽  
High Performance ◽  
High Performance Concrete ◽  
Great Influence ◽  
Ratio Increase ◽  
Excess Water ◽  
Packing Method ◽  
Condensed Silica Fume

The packing density of the powder in cement paste has great influence on the performance of the concrete. A higher packing density could at the same water/powder ratio increase the amount of excess water for lubricating the cement paste and thereby improve the flowability of the concrete. Alternatively, it would allow the water/powder ratio to be reduced to improve the strength of the concrete without compromising the flowability. Therefore, it is of great interest, especially for production of high-performance concrete, to maximize the packing density of the powder. This study aims to investigate the roles of superplasticizer and fillers in the packing density of the powder in cement paste. Packing density tests were carried out to determine the packing density of cement with various dosages of superplasticizer and different fillers (limestone fine, superfine cement and condensed silica fume) added using a newly developed wet packing method. The results showed that the addition of superplasticizer can significantly improve the packing density of cement while the addition of fillers can further improve the packing density of the powder.

Fresh State Behaviour of Cement Paste Containing Nano Kaolin

2014 ◽  
Vol 925 ◽  
pp. 28-32 ◽  
Author(s):  
Muhd Sidek Muhd Norhasri ◽  
M.S. Hamidah ◽  
A. Mohd Fadzil ◽  
A.G. Abd Halim ◽  
M.R. Zaidi
Keyword(s):  
Surface Area ◽  
Cement Paste ◽  
Setting Time ◽  
High Energy ◽  
Major Effect ◽  
Cement Replacement ◽  
High Energy Milling ◽  
Replacement Method ◽  
Fresh State ◽  
State Behaviour

The application of nanomaterials in cement by replacement method in concrete is becoming a trend in cement research. The utilisation of nanosilica, nanoalumina, titanium oxide and others are proven to enhance properties of concrete. The major effect of nanomaterials is its size in which it contributes to the packing theory due to increase in the surface area. nanokaolin which comes from kaolin, was tansformed to the nanoform by using high energy milling. The process of developing nanokaolin by using high energy milling is referred to process top to bottom approach in nanoprocessing technique. In this research, the nanokaolin will be used as an additive in cement by 7% weight of cement. Four (4) cement replacement materials catered by using metakaolin on weight basis from 0, 10%, 20% and 30% will also be adopted. To determine the fresh state, cement paste contains nanokaolin and metakaolin are tested its standard consistency and setting time. The effect of the inclusion of the nanokaolin as additive in cement paste that also contains metakaolin as cement replacement material will be investigated. It was found the inclusion of 7% nanokaolin increases the water demand of the cement paste level of metakaolin replacement. In addition to that, the setting time namely initial and final set was been delayed as compared to that of plain OPC. The nanoparticles of nanokaolin and also finer particles of metakaolin increase the surface area and refining the internal structure of cement paste which reduce the flow capabilities of cement paste containing nanokaolin and metakaolin.

Study of the pozzolanic activity and hydration products of cement pastes with addition of natural zeolites

Clay Minerals ◽  
2011 ◽  
Vol 46 (2) ◽  
pp. 241-250 ◽  
Author(s):  
V. Lilkov ◽  
O. Petrov ◽  
V. Petkova ◽  
N. Petrova ◽  
Y. Tzvetanova
Keyword(s):  
Surface Area ◽  
Cement Paste ◽  
Chemical Reactions ◽  
Natural Zeolite ◽  
Early Stage ◽  
Pozzolanic Activity ◽  
Large Surface Area ◽  
Natural Zeolites ◽  
Hydration Products ◽  
Cement Pastes

AbstractThis paper presents results from comparative thermogravimetric, calorimetric and pozzolanic activity analyses of five natural zeolite samples from Bulgaria, Slovakia, Philippines, USA and North Korea. The zeolites actively participate in the hydration processes of cement. Their activity in the early stage of hydration is based mainly on the large surface area of the particles while, in the later stages of activation, chemical reactions occur between the products of the hydration of cement and the soluble SiO2 that is present in the bulk of the zeolites. It has been shown that in all cement pastes which contain zeolite additives, the quantity of portlandite is lower than that in pure cement paste or is even totally absent. The amounts of hydration products are greater when 30% zeolite is used than when 10% zeolite is added (excluding the sample with chabazite). The lowest pozzolanic activity is shown by chabazite, which possessed the lowest SiO2/Al2O2 ratio.

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.

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