Active and passive monitoring of the early hydration process in concrete using linear and nonlinear acoustics

2009 ◽  
Vol 39 (5) ◽  
pp. 426-432 ◽  
Author(s):  
K. Van Den Abeele ◽  
W. Desadeleer ◽  
G. De Schutter ◽  
M. Wevers
Keyword(s):  
Nonlinear Acoustics ◽  
Hydration Process ◽  
Early Hydration ◽  
Passive Monitoring ◽  
Linear And Nonlinear

scholarly journals The Influence of Water Reducing Agents on Early Hydration Property of Ferrite Aluminate Cement Paste

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 731
Author(s):  
Chunlong Huang ◽  
Zirui Cheng ◽  
Jihui Zhao ◽  
Yiren Wang ◽  
Jie Pang
Keyword(s):  
Setting Time ◽  
Critical Role ◽  
Hydration Product ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Hydration Process ◽  
Early Hydration ◽  
Cement Pastes ◽  
Hydration Rate ◽  
Aluminate Cement

The ferrite aluminate cement (FAC) could rapidly lose fluidity or workability due to its excessive hydration rate, and greatly reduce the construction performance. Chemical admixtures are commonly used to provide the workability of cement-based materials. In this study, to ensure required fluidity of FAC, chemically different water reducing agents are incorporated into the FAC pastes. The experiments are performed with aliphatic water reducing agent (AP), polycarboxylic acid water reducing agent (PC) and melamine water reducing agent (MA), respectively. Influence of the water reducing agents on fluidity, setting time, hydration process, hydration product and zeta potential of the fresh cement pastes is investigated. The results show that PC has a better dispersion capacity compared to AP and MA. Besides decreasing water dosage, PC also acts as a retarder, significantly increasing the setting times, delaying the hydration rate and leading to less ettringite in the hydration process of FAC particles. The water reducing agents molecules are adsorbed on the surface of positively charged minerals and hydration products, however, for PC, steric hindrance from the long side chain of PC plays a critical role in dispersing cement particles, whereas AP and MA acting through an electrostatic repulsion force.

scholarly journals The Role of Titanium Dioxide on the Hydration of Portland Cement: A Combined NMR and Ultrasonic Study

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5364
Author(s):  
George Diamantopoulos ◽  
Marios Katsiotis ◽  
Michael Fardis ◽  
Ioannis Karatasios ◽  
Saeed Alhassan ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Hydration Process ◽  
Spin Lattice Relaxation ◽  
Hydration Reaction ◽  
Early Hydration ◽  
Cement Pastes ◽  
Spin Lattice ◽  
Pore Size Distributions

Titanium dioxide (TiO2) is an excellent photocatalytic material that imparts biocidal, self-cleaning and smog-abating functionalities when added to cement-based materials. The presence of TiO2 influences the hydration process of cement and the development of its internal structure. In this article, the hydration process and development of a pore network of cement pastes containing different ratios of TiO2 were studied using two noninvasive techniques (ultrasonic and NMR). Ultrasonic results show that the addition of TiO2 enhances the mechanical properties of cement paste during early-age hydration, while an opposite behavior is observed at later hydration stages. Calorimetry and NMR spin–lattice relaxation time T1 results indicated an enhancement of the early hydration reaction. Two pore size distributions were identified to evolve separately from each other during hydration: small gel pores exhibiting short T1 values and large capillary pores with long T1 values. During early hydration times, TiO2 is shown to accelerate the formation of cement gel and reduce capillary porosity. At late hydration times, TiO2 appears to hamper hydration, presumably by hindering the transfer of water molecules to access unhydrated cement grains. The percolation thresholds were calculated from both NMR and ultrasonic data with a good agreement between both results.

Effect of Calcined Red Mud Addition on the Hydration of Portland Cement

2012 ◽  
Vol 727-728 ◽  
pp. 1408-1411 ◽  
Author(s):  
Daniel Véras Ribeiro ◽  
João A. Labrincha ◽  
Márcio Raymundo Morelli
Keyword(s):  
Portland Cement ◽  
Red Mud ◽  
Setting Time ◽  
Cementitious Materials ◽  
Adiabatic Calorimeter ◽  
Hydration Process ◽  
Early Hydration ◽  
Bauxite Ore ◽  
Calorimetric Studies ◽  
Reference Mixture

The red mud (RM) is a solid waste derived from the processing of bauxite ore to produce alumina and it is considered a hazardous waste due to its high pH. This paper describes the use of mud untreated and after calcination at distinct temperatures (450, 650, and 1000°C) attempting to improve its reactivity. The Portland cement was replaced up to 30 wt% red mud, and its addition changed the hydration process, evaluated by calorimetric studies of early hydration and setting time. By comparing with the reference mixture (without red mud), the obtained results confirm the potential of the red mud to be used as pozzolanic additive to cementitious materials. Temperature of hydration was monitored by a quasi-adiabatic calorimeter (Langavant). The hydration temperature increases with RM addition, particularly if calcined in the same interval (450-650°C). In this condition, the hydration process is accelerated.

scholarly journals Early Hydration Process and Kinetics of Concrete Based on Resistivity Measurement

2021 ◽  
Vol 19 (3) ◽  
pp. 196-206
Author(s):  
Yongming Tu ◽  
Dongyun Liu ◽  
Lei Yuan ◽  
Tongfang Wang
Keyword(s):  
Resistivity Measurement ◽  
Hydration Process ◽  
Early Hydration ◽  
Kinetics Of

Resistivity Study on Early Hydration Process of Phosphoaluminate Cementitious Material

2009 ◽  
Vol 79-82 ◽  
pp. 95-98 ◽  
Author(s):  
Ming Zhang ◽  
Zhu Ding ◽  
Feng Xing ◽  
Peng Liu
Keyword(s):  
Resistivity Measurement ◽  
Heat Evolution ◽  
Hydration Process ◽  
Early Age ◽  
Hydration Products ◽  
Microstructure Formation ◽  
Time Curve ◽  
Early Hydration ◽  
Hydration Mechanism ◽  
Acceleration And Deceleration

An electrodeless resistivity measurement system developed recently can provide a reliable method for monitoring the hydration process of cement-based materials continuously and accurately. Phosphoaluminate cement (PAC) sets quickly and develops high early strength. In order to understand the mechanism, the hydration products and microstructure formation of PAC in early age need to be studied. In the study, early hydration process of PAC with different dosage of retarder was investigated by the electrodeless resistivity equipment. According to resistivity-time curve, resistivity of freshly mixed PAC paste decreases sharply and then rises slowly, some characteristic peaks appear at different hydration stages of PAC. Heat evolution of PAC was also measured. The hydration mechanism and structure formation were studied according to these results. Depending on the dosage of retarder, the hydration process of PAC includes four stages which are dissolution, induction, acceleration and deceleration.

Early hydration process of the cement-lime system

ce/papers ◽  
2018 ◽  
Vol 2 (4) ◽  
pp. 125-129
Author(s):  
Hui Zhang ◽  
Yufeng Su ◽  
Zhenghong Yang ◽  
Xiong Zhang
Keyword(s):  
Hydration Process ◽  
Early Hydration

Effects of Limestone Powder in Manufactured Fine Aggregate on Early Hydration Process and Types of Cement Hydrates

2009 ◽  
Vol 405-406 ◽  
pp. 262-266
Author(s):  
Ji Wei Cai ◽  
Shao Bo Zhang ◽  
Ming Kai Zhou ◽  
Bei Xing Li
Keyword(s):  
Fly Ash ◽  
Calcium Hydroxide ◽  
Hydration Process ◽  
Limestone Powder ◽  
Fine Aggregate ◽  
Dormant Period ◽  
Early Hydration ◽  
Acceleration Period ◽  
Hydrated Calcium

The crusher dust in Manufactured fine aggregate (MFA), e.g. limestone powder in calcareous MFA, constitutes micro gradation of the aggregate and suitable content of crusher dust in MFA can improve the properties of concretes. In this paper, early hydration processes of samples substituting limestone powder and fly ash for part of cement are analyzed, and effects of limestone powder on cement hydrates are studied through experiment of mortar prepared with MFA partially replaced by limestone powder and fly ash. The result reveals that both the dormant period and acceleration period of hydration ended earlier in the samples substituting limestone powder for part of cement, and amount of crystals of calcium hydroxide and hydrated calcium carboaluminate increases in hardened paste in the samples substituting limestone powder for part of MFA, i.e. calcareous dust (limestone powder) in MFA can stimulate and enhance hydration of cement.

Sign in / Sign up

Export Citation Format

Share Document