scholarly journals Water to Cement Ratio Effect on Cement Paste Microstructural Development by Electrical Resistivity Measurements and Computer Illustration

2021 ◽  
Vol 9 (3) ◽  
pp. 73-87
Author(s):  
Farqad Yousuf ◽  
Wei Xiaosheng
Keyword(s):  
Electrical Resistivity ◽  
Cement Paste ◽  
Microstructural Development ◽  
Cement Ratio ◽  
Ratio Effect ◽  
Resistivity Measurements ◽  
Water To Cement Ratio

scholarly journals CO2 Curing Efficiency for Cement Paste and Mortars Produced by a Low Water-to-Cement Ratio

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3883
Author(s):  
Seong Ho Han ◽  
Yubin Jun ◽  
Tae Yong Shin ◽  
Jae Hong Kim
Keyword(s):  
Cement Paste ◽  
Pressure Vessel ◽  
Gas Pressure ◽  
Strength Development ◽  
Co2 Uptake ◽  
Cement Pastes ◽  
Co2 Gas ◽  
Cement Ratio ◽  
Mix Proportion ◽  
Water To Cement Ratio

Curing by CO2 is a way to utilize CO2 to reduce greenhouse gas emissions. Placing early-age cement paste in a CO2 chamber or pressure vessel accelerates its strength development. Cement carbonation is attributed to the quickened strength development, and CO2 uptake can be quantitatively evaluated by measuring CO2 gas pressure loss in the pressure vessel. A decrease in CO2 gas pressure is observed with all cement pastes and mortar samples regardless of the mix proportion and the casting method; one method involves compacting a low water-to-cement ratio mix, and the other method comprises a normal mix consolidated in a mold. The efficiency of the CO2 curing is superior when a 20% concentration of CO2 gas is supplied at a relative humidity of 75%. CO2 uptake in specimens with the same CO2 curing condition is different for each specimen size. As the specimen scale is larger, the depth of carbonation is smaller. Incorporating colloidal silica enhances the carbonation as well as the hydration of cement, which results in contributing to the increase in the 28-day strength.

Limestone filler/cement ratio effect on the flow behaviour of a SCC cement paste

2013 ◽  
Vol 25 (5) ◽  
pp. 262-272 ◽  
Author(s):  
Francisco José Rubio-Hernández ◽  
Juan Manuel Morales-Alcalde ◽  
Ana Isabel Gómez-Merino
Keyword(s):  
Cement Paste ◽  
Flow Behaviour ◽  
Limestone Filler ◽  
Cement Ratio ◽  
Ratio Effect

Quantitative Characterization of Effective Porosity in Cement-Based Composite Materials

2010 ◽  
Vol 163-167 ◽  
pp. 3174-3179
Author(s):  
Guo Wen Sun ◽  
Jin Yang Jiang ◽  
Yun Sheng Zhang ◽  
Cai Hui Wang
Keyword(s):  
Composite Materials ◽  
Cement Paste ◽  
Pore Diameter ◽  
Effective Porosity ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Pore Characteristics ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
Second Peak

The method of the second intrusion mercury in MIP was used to investigate the pore characteristics of hardened cement paste with w/c ratio 0.23, 0.35 and 0.53, respectively, in order to research the quantitative relationship between transport properties and pore characteristics in cement-based composite materials. The results show the second intrusion mercury could well determine the effective pore structure parameters, and effective porosity accounts for 25% to 50% of total porosity in cement paste. At the same time, the existence of the first and second peak in pore size distribution curves is confirmed by MIP, such as, the first peak in hardened cement paste with water to cement ratio 0.53 is very distinct, however, with the decrease of water to cement ratio, the first peak gradually disappears. The pore diameter corresponding to the first and second peak is critical pore diameter of capillary pore and gel pore, respectively.

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.

Electrical Resistivity of Cement-Based Sensors under a Sustained Load

2014 ◽  
Vol 931-932 ◽  
pp. 436-440 ◽  
Author(s):  
Kraisit Loamrat ◽  
Manote Sappakittipakorn ◽  
Piti Sukontasukkul
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Creep Strain ◽  
Carbon Fibers ◽  
Compressive Force ◽  
Graphite Powder ◽  
Sustained Load ◽  
Test Results ◽  
Cement Ratio ◽  
Water To Cement Ratio

This research was to study the influence of a sustained load on the electrical resistivity of a cement-based sensor. The cement-based sensor in this study was made of cement paste having water to cement ratio of 0.4 with the addition of graphite powder at 2% and 4% by weight of cement and carbon fibers at 2% and 4% by volume. The sustained load was applied on the cement-based-sensor using a sustain machine to control a compressive force continually at 30% of its ultimate compressive strength for a period of 30 days. The test results showed that the sustained load induced a creep strain on the cement-based-sensor. The graphite incorporated cement-based sensor showed higher creep strain than the plain cement-based sensor while the carbon fiber cement-based sensor showed lesser. In addition, it was shown that the creep strains affect the electrical resistivity of the cement-based sensors.

Study on Synthesis and Application of Superplasticizer from Chitosan

2012 ◽  
Vol 430-432 ◽  
pp. 1207-1210
Author(s):  
Sheng Hua Lv ◽  
Jian Ping Duan ◽  
Rui Jun Gao ◽  
Qiang Cao
Keyword(s):  
Mechanical Properties ◽  
Sulfuric Acid ◽  
Cement Paste ◽  
Cement Ratio ◽  
Water To Cement Ratio

Sulfonated chitosan (SCS) was prepared from chitosan and sulfuric acid via sulfation reaction. SCS was used as superplasticizer in cement. The test showed that the maximum fluidity of the cement paste was 232 mm with dosage of 0.75 wt % at water to cement ratio (w/c) of 0.29. Meanwhile, lesser loss of fluidity and slump over 60 mins were observed comparing to naphthalene sulfonated formaldehyde condensates (NSF). A well-distribution of cement particles can be seen from the image of SEM in the sample of mortar prepared by SCS. The water reduce ratio of SCS reach 19.2 %. The applied results showed that SCS could slightly improve the mechanical properties of mortar. The paste fluidity, mechanical properties and slump loss of the cement paste incorporated SCS indicated that it can be used as superplasticizer in concrete.

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