Study on the strength development, hydration process and carbonation process of NaOH-activated Pisha Sandstone

2014 ◽  
Vol 66 ◽  
pp. 154-162 ◽  
Author(s):  
Jingliang Dong ◽  
Lijiu Wang ◽  
Tingting Zhang
Keyword(s):  
Hydration Process ◽  
Strength Development ◽  
Carbonation Process

scholarly journals Effect of nano-SnO2 on early-age hydration of Portland cement paste

2019 ◽  
Vol 11 (6) ◽  
pp. 168781401985194 ◽  
Author(s):  
Jianping Zhu ◽  
Genshen Li ◽  
Ruijie Xia ◽  
Huanhuan Hou ◽  
Haibin Yin ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Cement Hydration ◽  
Cementitious Materials ◽  
Hydration Process ◽  
Strength Development ◽  
Early Age ◽  
Test Machine ◽  
Portland Cement Paste ◽  
Scanning Electron

Nanomaterial, as a new emerging material in the field of civil engineering, has been widely utilized to enhance the mechanical properties of cementitious material. Nano-SnO2 has presented high hardness characteristics, but there is little study of the application of nano-SnO2 in the cementitious materials. This study mainly investigated the hydration characteristics and strength development of Portland cement paste incorporating nano-SnO2 powders with 0%, 0.08%, and 0.20% dosage. It was found that the early-age compressive strength of cement paste could be greatly improved when nano-SnO2 was incorporated with 0.08% dosage. The hydration process and microstructure were then measured by hydraulic test machine, calorimeter, nanoindentation, X-ray diffraction, scanning electron microscope, and mercury intrusion porosimetry. It was found that the cement hydration process was promoted by the addition of nano-SnO2, and the total amount of heat released from cement hydration is also increased. In addition, the addition of nano-SnO2 can promote the generations of high density C-S-H and reduce the generations of low density C-S-H indicating the nucleation effect of nano-SnO2 in the crystal growth process. The porosity and probable pore diameter of cement paste with 0.08% nano-SnO2 were decreased, and the scanning electron microscopic results also show that the cement paste with 0.08% nano-SnO2 promotes the densification of cement microstructure, which are consistent with the strength performance.

scholarly journals Sequential In-Situ Carbonation Process for the Preparation of Hand Sheets with Waste Lime Mud

Reactions ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 3-15
Author(s):  
Ramakrishna Chilakala ◽  
Thriveni Thenepalli ◽  
Seongho Lee ◽  
Hong Ha Thi Vu ◽  
Lai Quang Tuan ◽  
...  
Keyword(s):  
Paper Industry ◽  
Hydration Process ◽  
Smelting Process ◽  
Green Liquor ◽  
Carbonation Process ◽  
White Liquor ◽  
Lime Mud ◽  
Different Temperatures ◽  
Sample Purification ◽  
Process Elements

In the pulp and paper industry, the white liquor obtained from the causticizing green liquor in the smelting process mostly contains NaOH and Na2S. These chemicals are returned to the digester for reuse in the pulping process. The lime mud (LM) material is obtained from the reaction of the causticization process in paper industries. It is mainly composed of CaCO3; it appears with a green color with a high moisture content; and it has a small proportion of impurities such as non-process elements, for example Fe, Na, Mg, Al, Si, P, and S oxides and other toxic metals. This lime mud has poor whiteness with less efficiency due to its contaminated with impurities. The recycling or reutilizing process for lime mud and solid wastes are minimizing its toxic effect on the environment. The present study proposed to improve the whiteness of the waste lime mud by the calcination and hydration process at high temperatures and reutilizing it for hand sheets, making the process improve the paper brightness. In this study, we used a lime mud sample for calcination at 1000 °C and 1200 °C for 2 h and hydration at different times (3–24 h) with different temperatures (30–80 °C) and measured the powder whiteness and hand sheet brightness. The results indicated that after the calcination and hydration process, the lime mud sample whiteness was improved and that re-utilization with pulp for making hand sheets also can improve the paper brightness. It can be concluded that waste lime mud sample purification and the re-utilization process are more advantageous in paper industries.

The Effect of Initial Hydration Temperature on the Characteristics of Calcium Hydroxide and Aragonite Precipitated Calcium Carbonate

2007 ◽  
Vol 124-126 ◽  
pp. 815-818 ◽  
Author(s):  
Ji Whan Ahn ◽  
Jung Ah Kim ◽  
Kwang Suk You ◽  
Hwan Kim ◽  
Hee Chan Cho ◽  
...  
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Calcium Hydroxide ◽  
Initial Temperature ◽  
Process Condition ◽  
Hydration Process ◽  
Hydration Time ◽  
Precipitated Calcium Carbonate ◽  
Solid Ratio ◽  
Carbonation Process

Precipitated Calcium Carbonate (PCC) is obtained through three processes; that of calcination, hydration, and carbonation. Thus, changes in each process condition determine the particle size or morphology of the mediums (calcium oxide and calcium hydroxide) as well as the product (PCC). To date, studies concerning precipitated calcium carbonate have mainly focused on the carbonation process, aimed at the manufacturing of PCC. Thus far, few studies on calcination or hydration have been conducted. Calcium hydroxide is regarded as the most important factor during the carbonation process. It is obtained through a hydration process. Therefore, in order to create the valuable PCC studies that center on the hydration process should be carried out. The present study seeks to investigate the effect of the hydration condition, particularly the temperature, on the synthesis characteristics of calcium hydroxide and aragonite PCC. The results show that the particle size of calcium hydroxide changes with variations in the initial hydration temperature. In particular, a higher initial temperature resulted in a larger particle size of the calcium hydroxide used in the synthesis. The particle size and yield of aragonite also increased when calcium hydroxide created at high temperatures was used. However, the water/solid ratio or total amount at the hydration time had no effect on the manufacturing process of aragonite.

Activation of Ca-Based CO2 Sorbent by Hydration in Repetitive Calcination-Carbonation Reactions

2014 ◽  
Vol 587-589 ◽  
pp. 755-760
Author(s):  
Yu Qing Zhao ◽  
Chun Zhen Qiao ◽  
Wei Jiao Chen
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Radius ◽  
Hydration Process ◽  
Cycle Performance ◽  
Performance Study ◽  
Carbonation Process ◽  
Number Of Cycles

The carbonation characteristics of Ca-based CO2 absorbent hydrated by water were investigated as part of a multi-cycle performance study, and the change of the microstructure, pore radius and specific surface area of the absorbent with the number of cycles was researched. The results show that, conversion of sorbent hydrated by water is enhanced to 85% after 10 cycle, significantly higher than the 20% achieved by dry limestone cycle. Because the specific surface area is greatly enhanced, as well as the distributions of pore radius is improved in the hydration process, which develop an effective way to retain the fine qualities of Ca-based CO2 sorbents in a repetitive calcination-carbonation process.

scholarly journals The Role of Various Powders during the Hydration Process of Cement-Based Materials

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Shuhua Liu ◽  
Hongling Wang ◽  
Jianpeng Wei
Keyword(s):  
Early Stage ◽  
Steel Slag ◽  
Pozzolanic Reaction ◽  
Hydration Process ◽  
Limestone Powder ◽  
Strength Development ◽  
Early Hydration ◽  
Cement Based Materials ◽  
Early Strength

The role of various powders including glass powder (GP), limestone powder (LP), and steel slag powder (SSP) during the hydration process of cement-based materials was investigated by using X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), and strength tests. GP has adverse impact on early strength, but the pozzolanic reaction at later stage enhances the strength development greatly. LP can significantly improve early strength. SSP has a good contribution to the early and later strength of the paste when its content is less than 15%. GP has little effect on the kind of hydration products but relatively large effects on the quantity. Calcium hydroxide (CH) content of GP paste decreases over curing age gradually, which is different from pure cement paste because its pozzolanic activity consumes more CH than that generated from the cement hydration. SSP and LP mainly play a role of filling effect at early stage. Nucleating effect of LP also promotes the early hydration of cement. The hydration of LP occurs at later stage and forms the calcium carboaluminate hydrates. The hydration of SSP is relatively slow, which generates CH at later stage and is effective in the strength development.

Influence of Sucrose on Hydration Process of Portland Cement

2014 ◽  
Vol 599 ◽  
pp. 46-51 ◽  
Author(s):  
Zheng Hao Li ◽  
Wei Guo Shen ◽  
Qing Lan ◽  
Zi Li Lu ◽  
Liang Hong Cao ◽  
...  
Keyword(s):  
Solubility Product ◽  
Threshold Value ◽  
Hydration Product ◽  
Hydration Process ◽  
Strength Development ◽  
Threshold Values ◽  
High Solubility ◽  
Acceleration Threshold ◽  
Setting Process ◽  
Low Solubility

The sucrose (0.045%) is added in the cement paste, the consistency of Ca2+ and OH- reduce little, the AFt has high solubility product, thus the AFt exists as gel like product which covers the surface of the clinker particles, the sucrose acts as a retarder. When the dosage of the sucrose is 0.24%, the sucrose poisons the hydration of C2S and C3S markedly, so the consistency of Ca2+ and OH- reduce sharply, the AFt has low solubility product, the needle like AFt form a hydration product network and accelerates the setting process, C2S and C3S cannot yield enough C-S-H, the strength development is baffled. It was supposed that there are two dosage threshold values of sucrose on the hydration process, 0.01% is a retardation threshold value accelerating the formation of Aft, while 0.2% is an acceleration threshold value poisoning the hydration of C3S and C2S.

A Novel Method for Monitoring Hydration Process of Cement Paste Material

2014 ◽  
Vol 567 ◽  
pp. 333-338 ◽  
Author(s):  
Hashem Al-Mattarneh ◽  
Abdullah Alwadie ◽  
Ahmad Malkawi ◽  
Muhd Fadhil Nuruddin
Keyword(s):  
Cementitious Materials ◽  
Electrode System ◽  
Hydration Process ◽  
Electromagnetic Properties ◽  
Strength Development ◽  
Thermal Method ◽  
Frequency Range ◽  
Early Hydration ◽  
Plate Electrode ◽  
Novel Method

A new measurement system is developed to monitor the early hydration of cementitious materials based on measured dielectric properties of the material in low electromagnetic frequency range. The objectives of this paper were to evaluate the changes in the electromagnetic properties for samples with different fly ash content and to establish the reliability of the measurement technique by comparing with results obtained by traditional method such as thermal method that is either time consuming or impractical. The method adopted in the present experimental work is a parallel plate electrode system (PPES). The suggested monitoring device for concrete hydration and strength development is based on the relationship between the electromagnetic properties such as dielectric constant, loss factor and the strength development during hydration process and curing time. In this research the electromagnetic properties of concrete is found to be dependent on the hydration and strength of concrete. Therefore the development of microstructure and concrete compressive strength can be determined by monitoring its electromagnetic properties in the frequency range of 1 to 100 kHz.

Investigating the Carbonation and Mechanical Performance of Reactive MgO Cement Based Concrete Mixes

2018 ◽  
Vol 19 ◽  
pp. 23-33
Author(s):  
Cise Unluer
Keyword(s):  
Particle Size ◽  
Mechanical Performance ◽  
Inverse Correlation ◽  
Total Pore Volume ◽  
Strength Development ◽  
Accelerated Carbonation ◽  
Pore Connectivity ◽  
Carbonation Reaction ◽  
Carbonation Process ◽  
Porosity And Permeability

Carbonation governs the microstructure and the overall mechanical performance of mixes involving MgO cements as the main binder. Aggregate grading has a significant influence on the carbonation process due to the different particle arrangements that determine the porosity and permeability of the resulting formulations. This work investigates the effect of aggregate particle size distribution on the carbonation of blocks containing reactive MgO. Samples containing four different aggregate profiles were subjected to accelerated carbonation at 20% CO2 concentration for up to 28 days. While the influence of gap grading on strength development was not very pronounced, mixes with the lowest initial porosity indicated the greatest increase in density at the end of 28 days. This also translated into the highest strength results obtained due to the formation of hydrated magnesium carbonates, reaching 10 MPa only after 1 day of carbonation. The porosity values measured before carbonation were inversely correlated with the corresponding densities and final strengths of each mix. An inverse correlation between porosity and permeability values before carbonation led to the conclusion that the connectivity of pores rather than the total pore volume controls the carbonation reaction. Mixes with higher initial permeabilities achieved the highest strengths, proving that the extent of CO2 diffusivity is mainly dependent on pore connectivity.

Function Synergy of a New Type of Fluid Loss Additive Formula for Comprehensive Performance of Oil Well Cement

2020 ◽  
Vol 993 ◽  
pp. 1319-1332
Author(s):  
Hao Wang ◽  
Ming Li ◽  
You Zhi Zheng ◽  
Tao Gu
Keyword(s):  
Cement Hydration ◽  
Hydration Process ◽  
Strength Development ◽  
Fluid Loss ◽  
Oil Well ◽  
Chemical Absorption ◽  
Weight Percentage ◽  
Curing Period ◽  
Loss Control ◽  
Fluid Loss Additive

With 2-acrylamido-2-methylpropanesulfonic acid (AMPS) units on polymeric additive, additive showed high effectiveness used for oilwell cement. However, due to chemical absorption and chelation mechanism of AMPS units to Ca2+ hydrating cement particles, adding of AMPS type additives caused delay of cement hydration process. In this research, AMPS type fluid loss additive, named as FLA A additive, was studied for its hydration delay side effect to class G Portland cement. Furthermore, polyvinyl alcohol (PVA) polymer, modified by glyoxal and boric acid, called as PVAGB was used as a synergistic functional additive to AMPS type polymer fluid loss additive to research on hydration delay problem of AMPS type additive to cement and the improvement for the effectiveness of AMPS type fluid loss additive. When AMPS type additive showed functional drawbacks, with more disordered chemical absorption and chelation behaviors to Ca2+ hydrated cement particles rather than constituting a completed and superior fluid loss control system, and this kind of modified PVA polymer was utilized for making up its failure. New compound additive formula, PVAGB/FLA A fluid loss additive formula, was investigated, which showed superior and more stable fluid loss control ability, i.e. about 50 mL at 30°C and 108 mL at 80 °C with just 0.2 % BWOC (weight percentage by weight of cement) PVAGB and 0.5 %BWOC (weight percentage by weight of cement) FLA A addition. In addition, within 28-day curing period, cement samples showed a healthy compressive-strength development with no less than 28MPa after 7-day curing period rather than failure due to cement strength retrogression. With scanning electron microscope (SEM) analysis, PVAGB showed accelerating effect to cement hydration process, in which hexagonal plate Ca(OH)2 crystal and aggregated product of C-S-H gel were formed when compared with pure cement and cement with FLA A additive added.

Similarities and Differences in Shale, Aggregate Mixes and Concrete Containing Fly Ash

1988 ◽  
Vol 136 ◽  
Author(s):  
Petros E. Zenieris ◽  
Joakim G. Laguros
Keyword(s):  
Fly Ash ◽  
Maximum Level ◽  
Hydration Process ◽  
Strength Development ◽  
Chemical Agent ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Practical Result ◽  
X Ray ◽  
The Matrix

ABSTRACTFly ash technology has been very effective in providing stability in roadway base courses composed either of shale or aggregate materials, and also in partly replacing Portland cement in concrete. X-ray diffractometry and scanning electron microscopy observations indicate that there are certain similarities among these three types of mixes concerning the hydration process; on the other hand, there is evidence of distinct differences in the hydration products which are found to act either as a filler, a chemical agent, or both. Fly ash suppresses the intensity of the clay minerals in shale, speeds up the hydration process in concrete and acts partly as a filler in aggregate mixes. The net practical result is strength development which varies not only in terms of the maximum level attained, but also in regard to its rate. The conversion of ettringite to monosulfoaluminate proceeds at a rate which is considered high in concrete, moderate in aggregate mixes, and moderate to low in shale. X-ray diffraction analyses help to identify other dissimilarities in the minerals produced. The modification which takes place in the fabric and the matrix of the mixes is morphologically the same; in contrast, the growth of crystallites at the “particle”/fly ash interface is explicitly different. Preliminary quantification of matrix changes resulting from new hydration products is also explored.

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