Influence of Fly Ash on Alkalinity of Pore Solution and Microstructure Characteristics of Hardened Cement Pastes

2012 ◽  
Vol 253-255 ◽  
pp. 322-325 ◽  
Author(s):  
Jian Jun Yan ◽  
Xiang Li ◽  
Hua Quan Yang
Keyword(s):  
Fly Ash ◽  
Pore Solution ◽  
Cementitious Material ◽  
Ex Situ ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Microstructure Characteristics ◽  
Hardened Cement Pastes ◽  
Very High ◽  
Reaction Degree

Influence of fly ash on alkalinity of pore solution and microstructure characteristics of hardened cement pastes were investigated by means of ex-situ leaching (ESL), MIP and SEM. The results reveal that the decline of alkalinity of pore solution is not endless, even though the contents of fly ash in fly ash-cement(FC) pastes is very high(65%).The incorporation of fly ash in proper ratios could increase the ratio of harmless pores and improve the microstructure of the FC pastes. Ca(OH)2 was not consumed heavily or exhausted when cementitious material was hydrated due to the low reaction degree of fly ash.

Hydration Performance and Pore Structure of Fly Ash-Cement Pastes

2012 ◽  
Vol 204-208 ◽  
pp. 3867-3871 ◽  
Author(s):  
Xiang Li ◽  
Yun Dong ◽  
Hua Quan Yang
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Pore Solution ◽  
Ex Situ ◽  
Replacement Ratio ◽  
Cement Pastes ◽  
Binder Ratio ◽  
Very High ◽  
Reaction Degree ◽  
Curing Age

The hydration performance and pore structure of fly ash-cement (FC) pastes were investigated by means of XRD, TG, ex-situ leaching (ESL) and MIP. The results reveal that the influence of curing age to the kinds of hydration products of FC pastes is unconspicuous. As the content of fly ash increase, the Ca(OH)2 content decrease gradually. However, the content of Ca(OH)2 left in every paste is almost constant after 28d, regardless of the replacement ratio of fly ash and water-binder ratio. The decline of alkalinity of pore solution is not endless, even though the contents of fly ash in FC pastes is very high(65%).The incorporation of fly ash in proper ratios could increase the ratio of harmless pores and improve the microstructure of the FC pastes. Ca(OH)2 was not consumed heavily or exhausted when cementitious material was hydrated due to the low reaction degree of fly ash.

Assessment of Anhydrous Ethanol Extraction to Determine the Ionic Concentration of Hardened Cement Pastes

2010 ◽  
Vol 177 ◽  
pp. 506-509 ◽  
Author(s):  
Man Jian Wu ◽  
Wu Yao ◽  
Wei Wang ◽  
Yong Qi Wei
Keyword(s):  
Pore Solution ◽  
Ph Value ◽  
Ionic Concentration ◽  
Anhydrous Ethanol ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Ethanol Extraction ◽  
Alkali Ions ◽  
Ph Values ◽  
Hardened Cement Pastes

A new method involving the extraction of various ions from hardened cement pastes by anhydrous ethanol is presented to determine the pH value and ionic concentration during the first 28 days. The volume content of pore solution extracted by ethanol in the leachate reached 12% or above and the pH values calculated by alkali ions are more than 12, even up to 12.73. The results were compared with those from parallel, conventional pore water expression experiments. All of these comparisons verified the feasibility of the proposed method. However, the application of this method to pore solution analysis needs further improvement.

Assessment of Ultrasonic-Ethanol Extraction to Determine the pH Value of Hardened Cement Pastes

2011 ◽  
Vol 492 ◽  
pp. 451-454
Author(s):  
Xiao Ming Xing ◽  
Wu Yao
Keyword(s):  
Pore Solution ◽  
Ph Value ◽  
Anhydrous Ethanol ◽  
Hardened Cement ◽  
Simple Method ◽  
Cement Pastes ◽  
Ethanol Extraction ◽  
Ph Values ◽  
Hardened Cement Pastes ◽  
Variation Tendency

A simple method is presented to extract the pore solution of hardened cement pastes during the first 28 days and to measure the pH value, which is dependent on anhydrous-ethanol extraction (AEE) and improved by the assistance of ultrasonic vibration generator. The results were compared with the pore water expression (PWE) and anhydrous ethanol extraction through observing the variation tendency of pH values along with time and different water-cement ratios (w/c). The study showed that as w/c decreased, the pH value had a rising tendency; the density of [OH-] extracted by ultrasonic-ethanol extraction (UEE) method is 4-5 times higher than that by AEE method, which indicates the feasibility of UEE method.

scholarly journals Effect of Mineral Composition and w/c Ratios to the Growth of AFt during Cement Hydration by In-Situ Powder X-ray Diffraction Analysis

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4963
Author(s):  
Bo Chen ◽  
Yongming Zhang ◽  
Qing Chen ◽  
Fei Yang ◽  
Xianping Liu ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cement Hydration ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
X Ray ◽  
Hardened Cement Pastes ◽  
Maximum Content ◽  
Very High

AFt is one of the major products at the early stage of cement hydration. It is an important product that influences the performance of the fresh and hardened cement pastes such as the setting time. However, there is a lack of detailed investigation on the growth of AFt in the cement pastes with a long-time scale. In this work, we reported a detailed analysis by using in-situ powder X-ray diffraction (XRD) on the growth of AFt in the cement pastes during hydration. Samples of the hydrated ordinary Portland cement (OPC) and another locally produced Portland cement with very high tricalcium silicate (C3S) content with different water–cement (w/c) ratios were investigated continually till they were hydrated for about 270 days by powder XRD. The work shows that during Portland cement hydration, the AFt reaches its maximum content with very high speed within about 24 h, which is influenced by the content of C3S in the raw cement samples and the w/c ratios of the cement pastes. Once the maximum content of AFt was reached, it decreases very fast within the following couple of days, and then decreases slowly and finally reaches a stable level at the late stage of hydration. The results also present that a lower w/c ratio is beneficial to the formation of AFt and the conversion of AFt to AFm as well. While higher w/c ratios are favorable for the AFt to remain stable in the hardened cement pastes.

Long term study of hardened cement pastes containing silica fume and fly ash

2014 ◽  
Vol 60 ◽  
pp. 48-56 ◽  
Author(s):  
Vili Lilkov ◽  
Ivan Rostovsky ◽  
Ognyan Petrov ◽  
Yana Tzvetanova ◽  
Plamen Savov
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Hardened Cement ◽  
Term Study ◽  
Cement Pastes ◽  
Long Term Study ◽  
Hardened Cement Pastes

Chemical properties of pore solution of hardened cement pastes with mineral additions

2020 ◽  
pp. 1-11 ◽  
Author(s):  
Rachid Cherif ◽  
Ameur El Amine Hamami ◽  
Abdelkarim Aït-Mokhtar ◽  
Rafat Siddique
Keyword(s):  
Pore Solution ◽  
Chemical Properties ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Mineral Additions ◽  
Hardened Cement Pastes
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