Hot Pressed DSP Cement Paste

1991 ◽  
Vol 245 ◽  
Author(s):  
Ping Lu ◽  
J. Francis Young

ABSTRACTDSP cement paste is prepared by hot-pressing technique in this study in order to improve its particle packing and chemical composition, and to investigate the relationship between its solid phase microstructure and mechanical strength at the porosity close to zero. The addition of silica fume improves strength development, although capillary porosities are not changed significantly. Results obtained indicate that the highest compressive strength reached are 800 MPa after 28 days hydration and oven drying at 200°C. The strength has better relation with degree of hydration or the physical density of C-S-H. the silicate anion polymerization closes not appear to influence strength.

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3936 ◽  
Author(s):  
Jihoon Kim ◽  
Daiki Honda ◽  
Heesup Choi ◽  
Yukio Hama

When concrete is used for construction in cold-temperature regions, cold-resistant accelerators based on calcium nitrite (Ca(NO2)2) and calcium nitrate (Ca(NO3)2) are added to prevent early freezing damage. Although cold-resistant accelerators increase the early compressive strength and prevent early freezing damage by promoting cement hydration, the strength enhancement effect owing to the formation of such hydrates has not been evaluated quantitatively thus far. This study covers various types of analysis to understand the relationship between cement hydrate formation behavior and strength development upon the addition of varying amounts of nitrite-based accelerator. We find that the early compressive strength is enhanced by the addition of nitrite-based accelerator via the promotion of the relative production of monosulfate and C-S-H in the early age. However, the development of compressive strength decreases with an increase in the curing age. Furthermore, we find that the promotion of hydration reactions at an early age with the addition of nitrite-based accelerator can affect the formation ratio of each hydrate at a late age. We believe our findings can significantly contribute to developments in concrete application and allied fields.


1984 ◽  
Vol 42 ◽  
Author(s):  
Huang Yiun-Yuan ◽  
Ding Wei ◽  
Lu Ping

AbstractThe pore-structure strongly influences the carpressive strength of hardened cement paste (hcp) and other porous materials, as well as other mechanical properties. The simplest but most currently used expression representing the relationship between the pore-structure and compressive strength is fram Balshin: σ = σ0 (l-P)A, in which only the total porosity P is involved as a single parameter and σ0 and A are empirical constants. The influence of pore size distribution and pore shapes etc. are not considered.The authors introduce second parameter w - the factor of relative specific surface area of the pores other than the total porosity P into consideration and a new expression is proposed:σc=K11-p/1+2p(K2(1-p))K3w+K4 all the constants K1 - K4 can be determined experimentally. By using of this expression the new information relating the influence of pore-structure on the caopressive strength of hcp can be predicted.


2013 ◽  
Vol 423-426 ◽  
pp. 1051-1054
Author(s):  
Tian Yang Zhai

A fractal model to simulate cement paste internal pore structure, and on this basis deduce that fractal dimension is D and the corresponding pore is r, the relationship between porosity is P. MIP was measured test. Then calculated the different ages of the fractal dimension of cement and concrete compressive strength, tensile strength and permeability coefficient. The results showed that: compressive strength, permeability and fractal dimension has a good correlation. Whey in cement in the process of hydration of cement products continue to fill the pores, making the compressive strength increased 70%, permeability is declining.


2013 ◽  
Vol 11 (2) ◽  
pp. 155-161

High strength geopolymers were produced from coal combustion fly ashes. These matrices reached compressive strength values over 100 MPa, much stronger and denser than obtained by using Portland Cement binders. Size fractions were obtained by size separation techniques and the relationship between strength and particle size was investigated. The differences in compressive strength measured in the geopolymers made from fine fractions, the original fly ash and a coarse fraction of the same ash, were not significantly higher than the variation found for a reference geopolymer material. Therefore, a direct size-strength relationship could not be proven. Moreover, the chemistry and the pH of the fractions also varied, and this might as well has played a role in the strength development.


Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6273
Author(s):  
Chunping Gu ◽  
Jikai Yao ◽  
Yang Yang ◽  
Jie Huang ◽  
Linhao Ma ◽  
...  

Fly ash (FA) has been widely used in cement-based materials, but limited work has been conducted to establish the relationship between the compressive strength and hydration process of high-volume FA (HVFA)-cement-based material. In this study, the compressive strength and chemically bound water contents of FA-cement-based materials with different water-to-binder ratios (0.4, 0.5, and 0.6) and FA contents (0%, 30%, 40%, 50%, 60%, and 70%) were tested. Replacing more cement with FA reduced the compressive strength and of HVFA-cement-based materials. The compressive strength and chemically bound water content reduced by about 60–70% when 70% cement was replaced by FA. Water-to-binder ratio showed more significant influence on the chemically bonded water at later ages than that at early ages. Based on test results, the prediction equation of chemically bound water content was established, and its accuracy was verified. The error was less than 10%. The relationship between the compressive strength and chemically bound water content was also fitted. The compressive strength and chemically bound water content showed linear relationships for different water-to-binder ratios, hence the compressive strength of HVFA-cement mortar could be predicted with the chemically bound water content and water-to-binder ratios. The results of this study could be used for the prediction of the compressive strength development of HVFA-cement mortars, and is helpful to develop the mix design method of HVFA-cement-based materials.


2014 ◽  
Vol 621 ◽  
pp. 35-38 ◽  
Author(s):  
Rahimah Embong ◽  
Andri Kusbiantoro

This paper studies the effect of sodium chloride as the additive component in cement paste. Sodium chloride was included at 0.5%, 1%, 1.5%, and 2% by weight of cement content. Analysis on the performance of this reagent was conducted via setting time, compressive strength, and porosity test. Based on the setting time analysis, the inclusion of sodium chloride can extend the initial setting time of cement paste up to 24.91% longer than control specimen. Obstruction on the formation of calcium silicate hydrate gel by sodium and chloride ion was one of the possible causes to this phenomenon. Acceleration on the compressive strength development by sodium chloride was also detected. It appears that sodium chloride was able to de-flocculate the coagulated cement particles and reduced the viscosities of cement slurries; hence resulted in faster early hydration process.


2006 ◽  
Vol 36 (9) ◽  
pp. 1740-1743 ◽  
Author(s):  
Yong-Xin Li ◽  
Yi-Min Chen ◽  
Jiang-Xiong Wei ◽  
Xing-Yang He ◽  
Hong-Tao Zhang ◽  
...  

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