A simple, robust, and on-site microwave technique for determining water-to-cement ratio (w/c) of fresh Portland cement-based materials

2001 ◽  
Vol 50 (5) ◽  
pp. 1255-1263 ◽  
Author(s):  
K. Mubarak ◽  
K.J. Bois ◽  
R. Zoughi
Keyword(s):  
Portland Cement ◽  
Cement Ratio ◽  
Microwave Technique ◽  
Water To Cement Ratio ◽  
Cement Based Materials

Dispersion and Absorption of SBR Latex in the System of Mono-Dispersed Cement Particles in Water

2013 ◽  
Vol 687 ◽  
pp. 347-353 ◽  
Author(s):  
Xiao Xin Shi ◽  
Ru Wang ◽  
Pei Ming Wang
Keyword(s):  
Cement Hydration ◽  
Single Layer ◽  
Optical Microscope ◽  
Solution Phase ◽  
Environmental Scanning ◽  
Cement Particle ◽  
Microstructure Formation ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
Cement Based Materials

This paper investigates the dispersion of cement particles in water at different mix proportions using optical microscope, and the dispersion and absorption of SBR latex in the system of mono-dispersed cement particles in water using environmental scanning electron microscope (ESEM). The results show that the mono-dispersed cement can be well obtained at the water to cement ratio (mw/mc) of 10:1. The ESEM images present that SBR latex is dispersed on the surface of the cement particles as well as the solution phase. SBR latex does not prefer to be absorbed on the cement particles in spite of their opposite electric charge but chooses to be dispersed in the system proportionally. In addition, SBR particles are single-layer absorbed on the surface of cement particles in all the SBR latex to cement ratios (mp/mc). Several SBR particles absorbed on the surface of cement particle get close enough to form groups at the mp/mc of 15% and 20%. The results of this paper provide some bases for analyzing the influence of polymer on cement hydration and the microstructure formation of polymer-modified cement-based materials in a new view.

scholarly journals Effective Absorption Capacity Examined by Isothermal Calorimetry: Effect of Pore Structure and Water-to-Cement Ratio

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Joo-Ha Lee ◽  
Do Guen Yoo ◽  
Bo Yeon Lee
Keyword(s):  
Activated Carbon ◽  
Carbon Fibre ◽  
Pore Structure ◽  
Isothermal Calorimetry ◽  
Absorption Capacity ◽  
Cement Ratio ◽  
Effective Absorption ◽  
Water To Cement Ratio ◽  
Cement Based Materials ◽  
Activated Carbon Fibre

The accurate measurement of effective absorption capacity is crucial for highly absorptive materials when they are used within cement-based materials. In this study, a method for examining effective absorption capacity using isothermal calorimetry is reviewed and investigated in detail to accommodate different circumstances. Specifically, the effect of different pore structures and water-to-cement ratios in determining effective absorption capacity is experimentally examined using activated carbon fibre and powdered activated carbon. The results suggest that the method may be suitable for porous materials with micropores but not suitable for those with mesopores. Also, the results indicate that the effective absorption capacity value can change with the water-to-cement ratio used. These findings can be used to find the effective absorption capacity of highly absorptive materials more accurately using the isothermal calorimetry method.

scholarly journals Influence of Cement Type and Water-to-Cement Ratio on the Formation of Thaumasite

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Ailian Zhang ◽  
Linchun Zhang
Keyword(s):  
Portland Cement ◽  
Cement Mortar ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Strength Development ◽  
X Ray Diffraction ◽  
Limestone Filler ◽  
Visual Appearance ◽  
Cement Ratio ◽  
Water To Cement Ratio

Cement mortar prisms were prepared with three different cement types and different water-to-cement ratios plus 30% mass of limestone filler. After 28 days of curing in water at room temperature, these samples were submerged in 2% magnesium sulfate solution at 5°C and the visual appearance and strength development for every mortar were measured at intervals up to 1 year. Samples selected from the surface of prisms after 1-year immersion were examined by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The results show that mortars with sulfate resisting Portland cement (SRC) or sulphoaluminate cement (SAC) underwent weaker degradation due to the thaumasite form of sulfate attack than mortars with ordinary Portland cement (OPC). A lower water-to-cement ratio leads to better resistance to the thaumasite form of sulfate attack of the cement mortar. A great deal of thaumasite or thaumasite-containing materials formed in the OPC mortar, and a trace of thaumasite can also be detected in SRC and SAC mortars. Therefore, the thaumasite form of sulfate attack can be alleviated but cannot be avoided by the use of SAC or SRC.

scholarly journals Control of Drying Shrinkage of Magnesium Silicate Hydrate Gel Cements

2016 ◽  
Vol 709 ◽  
pp. 109-113 ◽  
Author(s):  
Ting Ting Zhang ◽  
Xiao Min Liang ◽  
M. Lorin ◽  
Zhen Lin Wu ◽  
Chris Cheeseman ◽  
...  
Keyword(s):  
Portland Cement ◽  
Magnesium Oxide ◽  
Silica Fume ◽  
Drying Shrinkage ◽  
Magnesium Silicate ◽  
Hydration Products ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
Order Of Magnitude ◽  
Forced Drying

Cracks were observed when the magnesium silicate hydrate gel cement (prepared by 40% MgO/ 60% silica fume) was dried. This drying cracking is believed to be caused when unbound water evaporates from the binder. The shrinkage upon forced drying to 200 °C of mortars made up from a reactive magnesium oxide, silica fume and sand was measured using dilatometry. The magnitude of the drying shrinkage was found to decrease when more sand or less water was added to the mortars and can be as low as 0.16% for a mortar containing 60 wt% sand and a water to cement ratio of 0.5, which is of a similar order of magnitude as observed in Portland cement based mortars and concretes. A simple geometrical interpretation based on packing of the particles in the mortar can explain the observed drying shrinkages and based on this analysis the drying shrinkage of the hydration products at zero added solid is estimated to be 7.3% after 7 days of curing.

scholarly journals Does a High Amount of Unhydrated Portland Cement Ensure an Effective Autogenous Self-Healing of Mortar?

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3298 ◽  
Author(s):  
Magdalena Rajczakowska ◽  
Lennart Nilsson ◽  
Karin Habermehl-Cwirzen ◽  
Hans Hedlund ◽  
Andrzej Cwirzen
Keyword(s):  
Portland Cement ◽  
High Performance ◽  
Cement Content ◽  
Healing Process ◽  
Self Healing ◽  
Aging Effects ◽  
Cement Ratio ◽  
Dense Microstructure ◽  
Water To Cement Ratio ◽  
Very High

It is commonly accepted that the autogenous self-healing of concrete is mainly controlled by the hydration of Portland cement and its extent depends on the availability of anhydrous particles. High-performance (HPCs) and ultra-high performance concretes (UHPCs) incorporating very high amounts of cement and having a low water-to-cement ratio reach the hydration degree of only 70–50%. Consequently, the presence of a large amount of unhydrated cement should result in excellent autogenous self-healing. The main aim of this study was to examine whether this commonly accepted hypothesis was correct. The study included tests performed on UHPC and mortars with a low water-to-cement ratio and high cement content. Additionally, aging effects were verified on 12-month-old UHPC samples. Analysis was conducted on the crack surfaces and inside of the cracks. The results strongly indicated that the formation of a dense microstructure and rapidly hydrating, freshly exposed anhydrous cement particles could significantly limit or even hinder the self-healing process. The availability of anhydrous cement appeared not to guarantee development of a highly effective healing process.

scholarly journals Physical and Chemical Aspects of the Nucleation of Cement-Based Materials

10.14311/1668 ◽  
2012 ◽  
Vol 52 (6) ◽  
Author(s):  
Pavel Demo ◽  
Alexey Sveshnikov ◽  
Šárka Hošková ◽  
David Ladman ◽  
Petra Tichá
Keyword(s):  
Cement Paste ◽  
Energy Barrier ◽  
Critical Size ◽  
Time Lag ◽  
Point Of View ◽  
Cement Ratio ◽  
Initial Stage ◽  
Water To Cement Ratio ◽  
Cement Based Materials ◽  
Physical And Chemical

A theoretical model of the nucleation of portlandite is proposed, and the critical size of a portlandite cluster and the energy barrier of nucleation are determined. The steady state nucleation rate and the time lag of the nucleation of portlandite are estimated for a pure solution of Ca(OH)2 in water. Possible connections with the corresponding properties for cement paste are discussed. A new method is developed for experimentally determining the concentration of Ca2+ ions during the initial stage of hydration of a cement paste. The time dependence of Ca2+ ions is measured for various water-to-cement ratio values. The results are discussed from the point of view of existing models of the induction period.

Relative Humidity of Blended Cement Pastes in Sealed during Hydration

2013 ◽  
Vol 539 ◽  
pp. 60-63
Author(s):  
Dan Jin ◽  
Wu Yao ◽  
Yi Chen
Keyword(s):  
Relative Humidity ◽  
Blended Cement ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
Cement Based Materials ◽  
Different Ages ◽  
Key Factor

As an important part of cement-based materials，water plays an important role during hydration and self-desiccation so the measurement of relative humidity or internal moisture in the research of cement-based materials is vital. In this paper, the measurement samples are blended cement pastes in sealed with different water to cement ratios and different kind of mineral admixtures. The measurement was taken at different ages during hydration to investigate the changes of relative humidity. The result showed that the water to cement ratio was the key factor of affecting the change of relative humidity, and the effect of mineral admixture kind was not very obvious in this experiment.

Calcined Kaolin Geopolymeric Powder: Influence of Water-to-Geopolymeric Powder Ratio

2012 ◽  
Vol 548 ◽  
pp. 48-53
Author(s):  
Y.M. Liew ◽  
H. Kamarudin ◽  
A.M. Mustafa Al Bakri ◽  
M. Binhussain ◽  
Luqman Musa ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Setting Time ◽  
Sem Analysis ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
Influence Of Water ◽  
Calcined Kaolin ◽  
Geopolymer Paste

This paper describes the synthesis of calcined kaolin geopolymeric powder from the alkaline activation of calcined kaolin followed by solidification and pulverizing process. The geopolymeric powder was used by just adding water to produce resulted geopolymer paste. In this paper, the effect of water-to-geopolymeric powder ratios on the properties of the resulted geopolymer paste was studied. This water-to-geopolymer powder ratio was similar to that of water-to-cement ratio in the case of ordinary Portland cement (OPC). However, the concept used here was based on geopolymerization process. The compressive strength, setting time and SEM analysis of the resulted geopolymer pastes were conducted. Highest strength was achieved at water-to-geopolymer powder ratio of 0.22. The resulted geopolymer paste could be handled up to 120 minutes and reached final setting after about 4 hours of setting. Microstructure showed the formation of geopolymeric gel after the addition of water to the geopolymeric powder.

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