scholarly journals THE EFFECT OF WATER TO CEMENT RATIO ON THE AUTOGENOUS SHRINKAGE OF CEMENT PASTE

2003 ◽  
Vol 68 (565) ◽  
pp. 1-7 ◽  
Author(s):  
Tomoaki HORITA ◽  
Toyoharu NAWA
Keyword(s):  
Cement Paste ◽  
Autogenous Shrinkage ◽  
Cement Ratio ◽  
Effect Of Water ◽  
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.

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.

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