scholarly journals Evaluation of the Effect of Fly Ash on Hydration Characterization in Self-Compacting Concrete (SCC) at Very Early Ages Using Piezoceramic Transducers

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2489 ◽  
Author(s):  
Yu Zheng ◽  
Dongdong Chen ◽  
Lingzhu Zhou ◽  
Linsheng Huo ◽  
Hongwei Ma ◽  
...  
Keyword(s):  
Fly Ash ◽  
Setting Time ◽  
Penetration Resistance ◽  
Electrical Signal ◽  
Experimental Results ◽  
Early Age ◽  
Hydration Reaction ◽  
Test Results ◽  
Self Compacting Concrete ◽  
Early Hydration

Nowadays, the industrial waste, Fly Ash (FA), as a mineral admixture or a replacement of cement for the production of self-compacting concrete (SCC) has been increasingly used, because of its benefits in enhancing both fresh and long-term concrete properties and in promoting environmental-friendly construction. In this study, the conventional cement was replaced by FA at different rates (0%, 20%, 40%, 60% of the cement mass) for the SCC mixtures. The early-age (0–24 h) SCC hydration, which is a complicated chemical reaction in pozzolanic behavior, was characterized by using a pair of piezoceramic Smart Aggregates (SAs). One SA works as an actuator and the other works as a sensor. A sweep sine signal from 100 Hz to100 kHz was used as the excitation signal, which is helpful to understand the quantitative influence of fly ash on the kinetics of SCC hydration. During the hydration reaction, the received electrical signal was continuously detected by the sensor. The experimental results showed that increasing the volume of fly ash resulted in longer pozzolanic reaction time in SCCs, which successfully reveals the effect of fly ash volume on the hydration behavior in early age (0–24 h) hydration. In order to quantitatively evaluate the hydration in the 0–24 h, based on the wavelet packet energy analysis, the hydration completion index (HCI) and normalized hydration completion index (NHCI) were defined. The experimental results showed that the NHCI can clearly reveal the hydration completion progress during the early hydration age (0–24 h). To validate the accuracy of the test results based on SAs, a series of mechanical tests for penetration resistance of SCCs with different volumes of fly ash were carried out. The results predicted by the signal based on SAs gave reasonable agreement with the test results of penetration resistance. It can be concluded that a successful investigation of the influence of fly ash on early-age SCC hydration response can be achieved based on the analysis of the received electrical signal using the proposed method and the important hydration characteristics, such as initial and final setting time, and can be approximately predicted by NHCI values.

scholarly journals Effects of Expansive Agents on the Early Hydration Kinetics of Cementitious Binders

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1900 ◽  
Author(s):  
Miao Miao ◽  
Qingyang Liu ◽  
Jian Zhou ◽  
Jingjing Feng
Keyword(s):  
Fly Ash ◽  
Hydration Heat ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Hydration Reaction ◽  
Hydration Kinetics ◽  
Early Hydration ◽  
Expansive Agent ◽  
Mechanical Performances ◽  
Kinetics Of

The addition of expansive agents could overcome the main disadvantages of raw concrete including high brittleness and low tensile strength. Few studies have investigated the early hydration kinetics of expansive cementitious binders, though the findings from the early hydration kinetics are helpful for understanding their technical performances. In this study, mixtures of 3CaO•3Al2O3•CaSO4 and CaSO4 (i.e., ZY-type™ expansive agent) with different proportions of mineral admixtures (e.g., fly ash and slag) were added into cement pastes to investigate the early hydration kinetics mechanism of expansive cementitious binders. Early hydration heat evolution rate and cumulative hydration heat were measured by isothermal calorimeter. Kinetic parameters were estimated based on the Krstulovic–Dabic model and Knudsen equations. Mechanical performances of expansive cementitious binders were tested in order to evaluate if they met the basic requirements of shrinkage-compensating materials in technical use. The early hydration heat released from cementitious binders containing ZY-type™ expansive agent was much greater than that released by pure cement, supporting the idea that addition of the expansive agent would improve the reaction of cement. The early hydration kinetic rates were decreased due to the reactions of the mineral admixture (e.g., fly ash or slag) and the ZY-type™ expansive agent in the cement system. The hydration reaction of cementitious binders containing ZY-type™ expansive agent obeyed the Krstulovic–Dabic model well. Three processes are involved in the hydration reaction of cementitious binders containing ZY-type™ expansive agent. These are nucleation and crystal growth (NG), interactions at phase boundaries (I), and diffusion (D). The 14-day expansion rates of cementitious binders containing ZY-type™ expansive agent are in the range of 2.0 × 10−4 to 3.5 × 10−4, which could meet the basic requirements of anti-cracking performances in technical use according to Chinese industry standard JGJ/T 178-2009. This study could provide an insight into understanding the effects of expansive agents on the hydration and mechanical performances of cementitious binders.

Experimental Study on the Engineering Characteristics of Improved Soil

2010 ◽  
Vol 168-170 ◽  
pp. 1426-1431
Author(s):  
Zhi Qing Li ◽  
Zhen Dong Cui ◽  
Yan Ping Wang ◽  
Li Chao Wang ◽  
Duo Zhong
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Fly Ash ◽  
Physical And Mechanical Properties ◽  
Hybrid Structure ◽  
Strength Characteristics ◽  
Shanxi Province ◽  
Hydration Reaction ◽  
Test Results ◽  
Shearing Strength

According to the typical loess in Shuozhou in Shanxi province, tests involved in compaction characteristics, shearing strength characteristics and disintegration are carried out by using loess and three kinds of improved loess, namely lime and fly-ash, lime and cement, cement and fly-ash. The best improved soil method is selected. The test results indicate that the compact hybrid structure is formed by fly ash and loess. The activity of fly ash is activated as a result of the lime mixing. A series of hydration reaction prompt the intensity of modified loess. And the physical and mechanical properties of improved loess are improved noticeably.

Study on the Influence of Mix Design Parameters on the Properties of Self-Compacting Concrete

2013 ◽  
Vol 857 ◽  
pp. 10-19
Author(s):  
Ji Liang Wang ◽  
Xiang Qian Wen ◽  
Jun Hong Shan ◽  
Ying Liu
Keyword(s):  
Fly Ash ◽  
Volume Content ◽  
Coarse Aggregate ◽  
Mineral Admixture ◽  
Design Parameters ◽  
Fine Aggregate ◽  
Test Results ◽  
Self Compacting Concrete ◽  
Volume Stability ◽  
Dry Shrinkage

the influence of mixing amount of mineral admixture, volume content of fine and coarse aggregate have been systematical studied on the workability, mechanical properties and volume stability of self-compacting concrete. Test results showed that with the fly ash content increased, the workability of self-compacting concrete improved significantly, early compressive strength decreased, but increase rate of later strength improved remarkably, and the mixing amount of fly ash inhibited significantly the dry shrinkage of self-compacting concrete; with the volume content of coarse aggregate increased, the workability of self-compacting concrete decreased significantly, but the volume stability of self-compacting concrete improved obviously, thus the optimum volume content of coarse aggregate of self-compacting concrete was range from 0.30 to 0.34; when the volume content of fine aggregate varied at the range of 0.40~0.50, there may be little effects on the workability of self-compacting concrete, but the increase self-compacting concretes volume content could reduce obviously the dry shrinkage of self-compacting concrete. Moreover, the variation in the volume content of coarse and fine aggregate should have slight influence on the early strength of self-compacting concrete, and the influence of the volume content variety on the later strength of self-compacting concrete could be neglected eventually.

scholarly journals Performance of Self-compacting Concrete with Stainless Steel Slag Versus Fly Ash as Fillers: A Comparative Study

2021 ◽  
Author(s):  
Yeong-Nain Sheen ◽  
Duc-Hien Le ◽  
My Ngoc-Tra Lam
Keyword(s):  
Stainless Steel ◽  
Compressive Strength ◽  
Fly Ash ◽  
Setting Time ◽  
Steel Slag ◽  
Strength Loss ◽  
Comparative Investigation ◽  
Self Compacting Concrete ◽  
Stainless Steel Slag ◽  
Initial Setting Time

Recently, stainless steel slag -a byproduct of manufacturing stainless steel is accepted as a cementitious material, the chemical characteristics of which are highly variant. This study reuses two types of stainless steel reducing slag with specific surface area of 1766 cm2/g (S1) and 7970 cm2/g (S2) in developing self-compacting concrete (SCC). Particularly, two S2-blended SCCs incorporating with S1 and fly ash as fillers (calling as S-mix and F-mix) were prepared for a comparative investigation. In both SCCs, ordinary Portland cement was replaced by S2 with various ratios (from 0 % to 50 %, increment 10 %). Testing results show that in fresh state, the F-mix exhibits higher workability and longer initial setting time than those of S-mix. In hardened state, 10 % compressive strength loss was realized as increasing S2 content up to 30 % in the both SCCs; the strength of F-mix is up to 1.9 times of S-mix at the same rate of S2 replacement. Water absorption of the F-mix was below 3 %, suggested as a “good” quality concrete; whilst the S-mix could be longs to an “average” one. Resistivity and sulfate resistance of F-mix are considerably higher than those of S-mix. Moreover, based on the obtained data, compressive strength and electrical resistivity are correlated well with a logarithmic form.

scholarly journals STRENGTH DEVELOPMENT OF CONCRETE WITH FLY ASH ADDITION

2007 ◽  
Vol 13 (2) ◽  
pp. 115-122 ◽  
Author(s):  
Marta Kosior-Kazberuk ◽  
Małgorzata Lelusz
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Mathematical Models ◽  
Statistical Methods ◽  
Experimental Results ◽  
Strength Development ◽  
Hardened Concrete ◽  
Test Results ◽  
Different Types ◽  
Compressive Strength Of Concrete

Based on experimental results, mathematical models were elaborated to predict the development of compressive strength of concrete with fly ash replacement percentages up to 30 %. Strength of concrete with different types of cement (CEM I 42.5, CEM I 32.5, CEM III 32.5), after 2, 28, 90, 180 days of curing, have been analysed to evaluate the effect of addition content, the time of curing and the type of cement on the compressive strength changes. The adequacy of equations obtained was verified using statistical methods. The test results of selected properties of binders and hardened concrete with fly ash are also included. The analysis showed that concrete with fly ash is characterised by advantageous applicable qualities.

scholarly journals A Comprehensive Study on the Hardening Features and Performance of Self-Compacting Concrete with High-Volume Fly Ash and Slag

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4286
Author(s):  
Zhenghong Yang ◽  
Sijia Liu ◽  
Long Yu ◽  
Linglin Xu
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Free Water ◽  
High Volume ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Main Concern ◽  
Self Compacting Concrete ◽  
Chloride Permeability ◽  
Early Hydration

The main concern of this work is to evaluate the influences of supplementary cementitious materials (fly ash, slag) and a new type of polycarboxylate superplasticizer containing viscosity modifying agents (PCE-VMA) on the performance of self-compacting concrete (SCC). The workability, hydration process, mechanical property, chloride permeability, degree of hydration and pore structure of SCC were investigated. Results indicate that the addition of fly ash and slag slows down early hydration and decreases the hydration degree of SCC, and thus leads to a decline in compressive strengths, especially within the first 7 days. The addition of slag refines pore structure and contributes to lower porosity, and thus the chloride permeability of SCC is decreased during the late hydration stage. Additionally, a new factor of calculated water–binder ratio is put forward, which can directly reflect the free water content of concrete mixture after mixing, and guide the mix proportion design of SCC.

Effect of Fly Ash on Mechanical Properties and Structure of CaO-Al2O3-P2O5-SiO2 System

2011 ◽  
Vol 55-57 ◽  
pp. 1233-1236
Author(s):  
Xiu Shu Tian ◽  
Shi Gang Mei ◽  
Shu Xia Ren
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Experimental Results ◽  
Early Age ◽  
Hydration Products ◽  
Different Ages ◽  
Early Strength ◽  
Gel System

In this paper, mainly CaO-Al2O3-P2O5-SiO2gel system and the effect of fly ash on the mechanical properties and the microstructure of the hydrated system without and within lay ash at different ages have been studied. The structures were characterized by XRD and SEM. The experimental results show that fly ash does not hydrate at the early age and provides the interface, so the hydration products of CaO-Al2O3-P2O5-SiO2system is deposited directly on its surface, which lead to a lower early strength; but fly ash hydrates at the later age and improves the hydration of CaO-Al2O3-P2O5-SiO2system.

scholarly journals The Relation between Concrete, Mortar and Paste Scale Early Age Properties

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1569
Author(s):  
Martin Klun ◽  
Vlatko Bosiljkov ◽  
Violeta Bokan-Bosiljkov
Keyword(s):  
Setting Time ◽  
Autogenous Shrinkage ◽  
Solidification Process ◽  
Early Age ◽  
S Wave ◽  
Conductivity Method ◽  
Early Hydration ◽  
High Maturity ◽  
Highly Correlated ◽  
The Cost

Microstructure development of concrete, mortar, and paste scale of cement-based material (CBM) during the early hydration stage has a significant impact on CBM’s physical, mechanical, and durability characteristics at the high maturity state. The research was carried out using compositions with increased autogenous shrinkage and extended early age period, proposed within the RRT+ programme of the COST Action TU1404. The electrical conductivity method, used to follow the solidification process of CBM, is capable of determining the initial and final setting time, and the end of the solidification process acceleration stage for the paste and mortar scale. Simultaneous ultrasonic P- and S-wave transmission measurements revealed that the ratio of velocities VP/VS is highly dependent on the presence of aggregates—it is considerably higher for the paste scale compared to the mortar and concrete scale. The deviation from the otherwise roughly constant ratio VP/VS for each scale may indicate cracks in the material. The non-linear correlation between the dynamic and static elastic moduli valid over the three scales was confirmed. Additionally, it was found that the static E-modulus correlates very well with the square of the VS and that the VS is highly correlated to the cube compressive strength—but a separate trendline exists for each CBM scale.

Basic Mechanics Properties Test of Fly Ash Concrete

2012 ◽  
Vol 238 ◽  
pp. 138-141
Author(s):  
Wei Xie ◽  
Hai Juan Zhang ◽  
Shu Shan Li
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Ash Content ◽  
Early Age ◽  
Test Results ◽  
Fly Ash Concrete ◽  
Influence Mechanism ◽  
Normal Reference ◽  
Test Study

By the test study of basic mechanics properties of concrete with different fly ash content, the influence of the content of fly ash on the compressive strength, flexural strength, splitting tensile strength and static compressive elastic modulus of concrete are analyzed with the explaining of the influence mechanism of fly ash. The test results show that, comparing with the normal reference concrete, the early age strength of fly ash concrete enhances slowly, while the late strength develops rapidly, even overpasses the strength of normal reference concrete.

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