scholarly journals EVALUATION OF PARTICLES’ COHESION AND DISPERSION STATES IN THE MIXING PROCESS OF CEMENT PASTE WITH LOW WATER-TO-BINDER RATIO

2015 ◽  
Vol 69 (1) ◽  
pp. 573-579
Author(s):  
Hiroshi NOMURA ◽  
Takafumi NOGUCHI
Keyword(s):  
Cement Paste ◽  
Mixing Process ◽  
Binder Ratio ◽  
Water To Binder Ratio

Effect of Fly Ash and Nano-CaCO3 on the Viscosity of Cement Paste

2013 ◽  
Vol 357-360 ◽  
pp. 968-971 ◽  
Author(s):  
Ren Juan Sun ◽  
Zhi Qin Zhao ◽  
Da Wei Huang ◽  
Gong Feng Xin ◽  
Shan Shan Wei ◽  
...  
Keyword(s):  
Fly Ash ◽  
Cement Paste ◽  
Bingham Model ◽  
Reduced Viscosity ◽  
Binder Ratio ◽  
Water To Binder Ratio

The effect of fly ash and nanoCaCO3 on the viscosity of pastes was studied. The rheological value of cement paste was determined by the rotation rheometer NXS-11B. In the study, five different dosages (0%, 20%, 30%, 40%, and 50%) of fly ash and three levels of nanoCaCO3, 0.5%, 1%, and 2.5%, were considered. Viscosity of the pastes, made with fly ash and nanoCaCO3 at a constant water-to-binder ratio of 0.35, were measured and analyzed. The results indicate that the pastes with fly ash or/and nanoCaCO3 still fit the Bingham model. The addition of fly ash reduced viscosity, however, the addition of nanoCaCO3 increased viscosity. The effect of nanoCaCO3 is more significantly than fly ash on viscosity.

scholarly journals EARLY AGE POROSITY AND PORE SIZE DISTRIBUTION OF CEMENT PASTE WITH FLUE GAS DESULPHURISATION (FGD) WASTE

2013 ◽  
Vol 19 (5) ◽  
pp. 622-627 ◽  
Author(s):  
Jamal M. Khatib ◽  
Pritpal S. Mangat ◽  
Lee Wright
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Cement Paste ◽  
Flue Gas ◽  
Early Stage ◽  
Early Age ◽  
Cement Pastes ◽  
Binder Ratio ◽  
Water To Binder Ratio

This paper is part of a wide-ranging investigation on the use of flue gas desulphurisation (FGD) waste in cement-based materials. It reports the results on the porosity and pore size distribution of cement paste containing varying amounts of simulated FGD waste. The water to binder ratio was 0.5. The binder consists of cement and simulated FGD. The FGD is a combination of fly ash and gypsum ranging from 0% to 100%. Cement in the pastes was partially replaced with 25% FGD (by weight). The porosity and pore size distribution of cement pastes was determined during the early stage of hydration. Increasing the amount of gypsum does not increase the pore volume. However, increasing the amount of gypsum in the paste leads to an increase in the threshold diameter and a decrease in the percentage of small pores in the paste, both indicating a coarser pore structure. The results of this investigation were compared with data at longer curing periods.

Experimental and Modeling Studies on Thermal Conductivity of Cement Composites Containing Nanosilica

2014 ◽  
Vol 979 ◽  
pp. 119-123
Author(s):  
Pongsak Jittabut ◽  
Prinya Chindaprasirt ◽  
Supree Pinitsoontorn
Keyword(s):  
Thermal Conductivity ◽  
Cement Paste ◽  
Building Energy ◽  
Cement Composites ◽  
Building Energy Efficiency ◽  
Cement Pastes ◽  
Research Article ◽  
Binder Ratio ◽  
Nanosilica Particle ◽  
Water To Binder Ratio

This research article was presented the thermal conductivity of cement pastes containing nanosilica. The effects of nanosilica particle size and concentration determined by mixing three nanosilica particle sizes of 12, 50 and 150 nm, using nanosilica were of 1-5 wt%. The water to binder ratio of 0.5 was used. The thermal properties test were subsequently measured in terms of thermal conductivity coefficient using ISOMET 2114. The thermal conductivities of cement paste is thus numerically calculated and the predictions are compared with the existing experimental data. A unifying equation for four fundamental effective thermal conductivity structural models (Series, Parallel, one-dimensional heat flow, Maxwell’s model) was derived. The best prediction was provided by a composite model that combined the Maxwell’s model. Consequently, applications of nanosilica cement paste in building constructions may be an interesting solution in order to improve sustainability and building energy efficiency.

scholarly journals Volume Stability of Cement Paste Containing Limestone Fines

Buildings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 366
Author(s):  
Jamal Khatib ◽  
Rawan Ramadan ◽  
Hassan Ghanem ◽  
Adel Elkordi
Keyword(s):  
Cement Paste ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Chemical Shrinkage ◽  
Total Period ◽  
Volume Stability ◽  
Cement Replacement ◽  
Binder Ratio ◽  
Limestone Fines ◽  
Water To Binder Ratio

The common cause of cracking in cement paste is shrinkage due to different reasons, such as loss of water and chemical reactions. Incorporating limestone fines (LF) as a cement replacement can affect the shrinkage of the paste. To examine this effect, five paste mixes were prepared with 0, 5, 10, 15 and 20% LF as a cement replacement and with a water-to-binder ratio (w/b) of 0.45. Four volume stability tests were conducted for each paste: chemical, autogenous and drying shrinkage and expansion. Chemical shrinkage was tested each hour for the first 24 h and thereafter every 2 days for a total period of 90 days. The drying shrinkage, autogenous shrinkage and expansion were monitored every 2 days until 90 days. The results showed that replacing 15% LF enhanced the chemical shrinkage of the paste. However, autogenous shrinkage of the paste was found to increase between 0 and 10% LF and decline sharply at 15 and 20% LF. Drying shrinkage was found to increase with the increase in LF content. Expansion exhibited little variation between 0 and 10% LF and an increase for replacement above 15% LF. These results are discussed in terms of the formation of hydration products and self-desiccation due to hydration.

The Relationship between the Strength and the Pore Structures of Cement Paste with Mineral Admixtures

2011 ◽  
Vol 250-253 ◽  
pp. 104-108 ◽  
Author(s):  
Yue Li ◽  
Jun Ling Bao ◽  
Chun E Sui ◽  
Xiu Li Du
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Cement Paste ◽  
Mapping Function ◽  
Mineral Admixtures ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Binder Ratio ◽  
Water To Binder Ratio ◽  
The Relationship

This paper presents the effects of mineral admixtures and the water to binder ratio (W/B) on the tensile and compressive strength and micro pore structure of hardened cement pastes. The test results show that: with the water to binder ratio increasing, the tensile and compressive strength of cement paste with different mineral admixtures will decrease, air content and mean pore diameter will decrease and the cement paste with the ground blast furnace slag is the lowest. The artificial neural network based on its nonlinear mapping function can fit the relationship between strength and pore structure more accurate than an empirical formula.

Assessing Rheological Properties of Cement Paste as a First Step in Predicting Robustness of Self-compacting Concrete

2018 ◽  
Vol 69 (7) ◽  
pp. 1733-1739
Author(s):  
Marius Dumitrescu ◽  
Alina Badanoiu ◽  
Constantin Dorinel Voinitchi ◽  
Georgeta Voicu
Keyword(s):  
Cement Paste ◽  
Rheological Behavior ◽  
Cement Hydration ◽  
Great Influence ◽  
Hydration Process ◽  
X Ray Diffraction ◽  
Self Compacting Concrete ◽  
Binder Ratio ◽  
Early Strength ◽  
Water To Binder Ratio

This paper proposes a methodology to assess the rheological behavior of cement paste as a first step to linking this behavior to the robustness of the Self Compacting Mortar (SCM) and further extending this to Self-Compacting Concrete (SCC). Cement paste�s rheological behavior was assessed in terms of spread (using a mini-cone) and time of flow (using the Marsh cone). The results show that the type of superplasticizer (SP) admixture has a great influence on the rheological behavior of cement paste and for each combination of binder and superplasticizer admixture there is a specific range of water to binder ratio in which the rheology of paste seems to be appropriate for obtaining a robust SCC mix. The influence of SP and limestone filler addition on the kinetic of cement hydration process was assessed by X Ray Diffraction and thermal analysis (TG-DTA). Based on these results, i.e. an important delaying effect exerted by superplasticizer additions on cement hydration process at early ages (1 day), it can be concluded that when designing SCC for the precast industry - where the early strength of concrete is of high importance, analyzing the early strength of binder paste together with the robustness properties is very important. The correlation between the two aspects - rheology and early strength -is very important in this case in order to obtain applicable results in practice.

TSMT Technics to Prepare DSP Mortar

2011 ◽  
Vol 261-263 ◽  
pp. 642-647 ◽  
Author(s):  
Liang Li Gao
Keyword(s):  
Compressive Strength ◽  
Water Bath ◽  
Mix Design ◽  
Design Parameters ◽  
Mixing Process ◽  
Binder Ratio ◽  
Water To Binder Ratio ◽  
High Flowability ◽  
Environmental Sem ◽  
Wedge Splitting

This study proposes a new mixing process for producing commercially acceptable DSP mortar of high flowability, using commercial materials and water-bath curing at about 20°C. That is “three- speed mixing technics (TSMT)”. The properties of mortars mixed by TSMT and conventional technics (CT) are compared. At a water-to-binder ratio of 0.2, the compressive strength of the TSMT mixed DSP mortars was about 41.2% higher than that of the CT mixed DSP mortars of the same composition, the workability was also increased. The increase reason was investigated by the wedge-splitting section and Environmental SEM (ESEM) images. Additionally, for TSMT, the influence of mix-design parameters such as cement grade, the water/binder (w/b) ratio, the silicon fume/cement (sf/c) ration and the superplasticizer/cement (sp/c) ratio were studied.

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