scholarly journals Application of ultrasonic pulse velocity for assessment of thermal expansion coefficient of concrete at early age

2016 ◽  
Vol 50 (1) ◽  
Author(s):  
Semion Zhutovsky ◽  
Konstantin Kovler
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Early Age

Research on Method of Separating Autogenous Shrinkage from Thermal Deformation of Concrete at Early Ages

2012 ◽  
Vol 193-194 ◽  
pp. 486-491
Author(s):  
Li Xie ◽  
Wu Yang Ding
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Thermal Deformation ◽  
Autogenous Shrinkage ◽  
Temperature History ◽  
Early Age ◽  
Two Phase ◽  
Research Status ◽  
Selection Of

In order to separate early-gae autogenous shrinkage from thermal deformation, it is the key to measure accurately thermal expansion coefficient of concrete at early ages. By analysing deeply the research status of early-age thermal expansion coefficient of concrete, the influences of temperature history on early-age autogenous shrinkage and the selection of thermal expansion coefficient are discussed. Moreover, based on the existing methods of separating early-gae autogenous shrinkage from thermal deformation, the more reasonable two-phase separating method considering concrete ages is provided.

scholarly journals Evaluation of Concrete Quality for Reinforced Concrete Frame Members Exposed to Natural Fires at Early Ages Using in situ Test Methods

2019 ◽  
Vol 13 (1) ◽  
pp. 201-209
Author(s):  
Muhammad I. Omer ◽  
Dilshad K. Jaf
Keyword(s):  
Reinforced Concrete ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Early Age ◽  
Concrete Frames ◽  
Natural Fire ◽  
Concrete Quality ◽  
Fire Accidents

Background: In recent years, numerous reinforced concrete buildings have been constructed in Iraq and some developing countries. Fire accidents occur in wooden formwork especially during the summer season due to problems associated with the construction procedure and on-site management. And fires can erupt during the construction stage of buildings. Introduction: Generally, if fire accidents occur in a wooden formwork, in these situations the concrete in the field is at an early age (i.e., “young”). The internal structure and chemical composition of early-age concrete are different from that of the carrier due to incomplete hydration at an early age. This study aimed to evaluate the strength of reinforced concrete frames at early ages when exposed to natural fire. The evaluation of existing buildings is an important issue that involves researchers and engineers in many countries. Methods: The experimental program consisted of constructing three full-scale reinforced concrete frames that are then exposed to natural fire. When the concrete age reaches three and five days by firing its formwork, the concrete quality of the structure was evaluated via ultrasonic pulse velocity as a nondestructive measurement. Core test was used as a destructive technique to implement a relationship between compressive strength and nondestructive measurements Results: The results showed that the frame exposed to natural fire early was generally more affected than the other frame, and its compressive strength was reduced close to 33%. The results also showed that the ultrasonic pulse velocity test for the structural elements was smaller than those of the core test Conclusion: It can be concluded that the current assessment methodology must be evaluated to provide practical suggestions that can enhance the reliability of assessing the in situ strength of existing concrete structures by nondestructive tests and cores.

Influence of EVA Copolymer Latex on Cement Hydration and Microstructures of Modifed Mortars

2014 ◽  
Vol 599 ◽  
pp. 56-60
Author(s):  
Ji Zhou ◽  
Can Lin Zhang ◽  
Cheng Cheng Jiang ◽  
Jian Ying Yu
Keyword(s):  
Cement Hydration ◽  
Cement Mortar ◽  
Bound Water ◽  
Ethylene Vinyl Acetate ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Early Age ◽  
Calcium Silicate Hydration ◽  
Sem Analyses

This article deals with the effect of ethylene-vinyl acetate (EVA) on cement hydration and microstructures of modified mortars. Ultrasonic pulse velocity (UPV) and chemically bound water are investigated to characterize cement hydration of modified mortars. The addition of EVA decreases the cement hydration before 7 day, and increases cement hydration after 7 day. Cement hydration of EVA-modified mortar is close to pure cement mortar at 28 day. Scanning electron microscope (SEM) analyses show that cement particles are encased by the EVA at early age, which prevents the cement hydration. Hydration products generate in large quantities, and polymer film crosslinks with calcium silicate hydration (C-S-H) after 28 day.

Ultrasonic pulse velocity for determining the early age properties of dry-cast concrete containing ground granulated blast-furnace slag

2007 ◽  
Vol 34 (5) ◽  
pp. 682-685 ◽  
Author(s):  
D K Panesar ◽  
S E Chidiac
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Blast Furnace Slag ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Early Age ◽  
Granulated Blast Furnace Slag ◽  
Cast Concrete ◽  
Furnace Slag

This study evaluates the potential use of ultrasonic pulse velocity (UPV) for determining the early age compressive strength of dry-cast concrete containing varying percentages of ground granulated blast-furnace slag (GGBFS). The proposed approach includes computing the dynamic elastic modulus from UPV measurements, evaluating the static elastic modulus from experimentally measured dynamic-to-static elastic modulus ratios, and determining the compressive strength from the static elastic modulus using formulae suggested in ACI-363. The early age strengths of dry-cast concrete containing varying amount of GGBFS, which are determined using UPV measurements, are in good agreement with the measured strength. The evaluation is also extended to include five datasets reported in published literature for concrete containing varying types and amounts of mineral admixtures. Key words: concrete, compressive strength, dry cast, early age properties, ground granulated blast-furnace slag (GGBFS), ultrasonic pulse velocity (UPV).

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