Prediction of early-age compressive strength of epoxy resin concrete using the maturity method

2017 ◽  
Vol 152 ◽  
pp. 990-998 ◽  
Author(s):  
Nan Ji Jin ◽  
Inbae Seung ◽  
Yoon Sang Choi ◽  
Jaeheum Yeon
Micromachines ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 559 ◽  
Author(s):  
Tareen ◽  
Kim ◽  
Kim ◽  
Park

Recently, the early-age strength prediction for RC (reinforced concrete) structures has been an important topic in the construction industry, relating to project-time reduction and structural safety. To address this, numerous destructive and NDTs (non-destructive tests) are applied to monitor the early-age strength development of concrete. This study elaborates on the NDT techniques of ultrasonic wave propagation and concrete maturity for the estimation of compressive strength development. The results of these comparative estimation approaches comprise the concrete maturity method, penetration resistance test, and an ultrasonic wave analysis. There is variation of the phase transition in the concrete paste with the changing of boundary limitations of the material in accordance with curing time, so with the formation of phase-transition changes, changes in the velocities of ultrasonic waves occur. As the process of hydration takes place, the maturity method produces a maturity index using the time-feature reflection on the strength-development process of the concrete. Embedded smart temperature sensors (SmartRock) and PZT (piezoelectric) sensors were used for the data acquisition of hydration temperature history and wave propagation. This study suggests a novel relationship between wave propagation, penetration tests, and hydration temperature, and creates a method that relies on the responses of resonant frequency changes with the change of boundary conditions caused by the strength-gain of the concrete specimen. Calculating the changes of these features provides a pattern for estimating concrete strength. The results for the specimens were validated by comparing the strength results with the penetration resistance test by a universal testing machine (UTM). An algorithm used to relate the concrete maturity and ultrasonic wave propagation to the concrete compressive strength. This study leads to a method of acquiring data for forecasting in-situ early-age strength of concrete, used for secure construction of concrete structures, that is fast, cost effective, and comprehensive for SHM (structural health monitoring).


2017 ◽  
Vol 2017 ◽  
pp. 1-12
Author(s):  
Nan Ji Jin ◽  
Kyu-Seok Yeon ◽  
Seung-Ho Min ◽  
Jaeheum Yeon

The compressive strength of vinyl ester polymer concrete is predicted using the maturity method. The compressive strength rapidly increased until the curing age of 24 hrs and thereafter slowly increased until the curing age of 72 hrs. As the MMA content increased, the compressive strength decreased. Furthermore, as the curing temperature decreased, compressive strength decreased. For vinyl ester polymer concrete, datum temperature, ranging from −22.5 to −24.6°C, decreased as the MMA content increased. The maturity index equation for cement concrete cannot be applied to polymer concrete and the maturity of vinyl ester polymer concrete can only be estimated through control of the time interval Δt. Thus, this study introduced a suitable scaled-down factor (n) for the determination of polymer concrete’s maturity, and a factor of 0.3 was the most suitable. Also, the DR-HILL compressive strength prediction model was determined as applicable to vinyl ester polymer concrete among the dose-response models. For the parameters of the prediction model, applying the parameters by combining all data obtained from the three different amounts of MMA content was deemed acceptable. The study results could be useful for the quality control of vinyl ester polymer concrete and nondestructive prediction of early age strength.


2020 ◽  
Vol 309 ◽  
pp. 103-107
Author(s):  
Pavel Kasal ◽  
Václav Lorenc ◽  
Werner Wenighofer

This paper describes four projects which were built with the use of concrete monitoring system of early age compressive strength based on maturity method. The paper also deals with experiences and benefits which came from the usage of monitoring system in these projects. First two examples are bridge projects „Petersdorfer See“ and „Seckachtal“ from Germany. The third project is a retirement home in Germany and the last example is Czech project of office building Vlněna in Brno. Maturity methods for estimating early age compressive strength of concrete are known since the 1950s. These methods use the principle that compressive strength is related to age, temperature history and concrete mix properties. Before the use of this method, each different concrete mix in use needs to be calibrated. Then temperature and time are measured since the concrete is poured. Several systems using maturity method for estimating real time compressive strength are available on the market. The use of these systems helps to determine earliest possible time for stripping the formwork, loading the structure, application of post tensioning forces and other critical operations during the construction time.


2020 ◽  
Vol 309 ◽  
pp. 98-102
Author(s):  
Jan Tichý ◽  
Pavel Kasal ◽  
Václav Lorenc ◽  
Petr Cikrle ◽  
Dalibor Kocáb

Construction company Skanska a.s. is active in the field of reinforcement structures. Skanska finds measuring of early-age compressive strength very important because of removing of the formwork. This paper deals with three nondestructive methods for estimating compressive strength. Skanska started a collaboration with institute of building testing FAST VUT at the beginning of the year. Collaboration was focused on measuring of early-age strength of concrete with rebound hammer SilverSchmidt PC L. The paper includes the equation for calculation of compressive strength of C 30/37 XC4 from the rebound coefficient. Evaluation was done using results from rebound hammer and press value of crushed cubes. Calculated equation was compared with equation provided by producer of the hammer. This paper also deals with Concremote monitoring system, which is used for estimating early age compressive strength in the structure. This system, offered by company Doka, is based on maturity method. This paper shortly presents experiences with use of Concremote on site BD Hornomecholupska.


2021 ◽  
Author(s):  
Biruk Hailu Tekle ◽  
Safat Al‐Deen ◽  
Mohammad Anwar‐Us‐Saadat ◽  
Njoud Willans ◽  
Yixia Zhang ◽  
...  

2019 ◽  
Vol 32 (3) ◽  
pp. 306-315 ◽  
Author(s):  
Liang Xu ◽  
Yi He ◽  
Shaohua Ma ◽  
Li Hui

T800/high-temperature epoxy resin composites with different hole shapes were subjected to hygrothermal ageing and thermal-oxidative ageing, and the effects of these different ageing methods on the open-hole properties of the composites were investigated, including analyses of the mass changes, surface topography changes (before and after ageing), fracture morphologies, open-hole compressive performance, dynamic mechanical properties and infrared spectrum. The results showed that only physical ageing occurred under hygrothermal ageing (70°C and 85% relative humidity), and the equilibrium moisture absorption rate was only approximately 0.72%. In contrast, under thermal-oxidative ageing at 190°C, both physical ageing and chemical ageing occurred. After ageing, the open-hole compressive strength of the composite laminates with different hole shapes decreased significantly, but the open-hole compressive strength after thermal-oxidative ageing was greater than that after hygrothermal ageing. Among the aged and unaged laminates, the laminates with round holes exhibited the largest open-hole compressive strength, followed by those with the elliptical holes, square holes and diamond holes. The failure modes of the laminates were all through-hole failures. The unaged samples had a glass transition temperature ( T g) of 226°C, whereas the T g of the samples after hygrothermal ageing was 208°C, which is 18°C less than that of the unaged samples, and the T g of the samples after thermal-oxidative ageing was 253°C, which is 27°C greater than that of the unaged samples.


2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yongli Xu ◽  
Guang Yang ◽  
Hongyuan Zhao

For cement-based materials, the curing temperature determines the strength gain rate and the value of compressive strength. In this paper, the 5% cement-stabilized macadam mixture is used. Three indoor controlled temperature curing and one outdoor natural curing scenarios are designed and implemented to study the strength development scenario law of compressive strength, and they are standard temperature curing (20°C), constant low temperature curing (10°C), day interaction temperature curing (varying from 6°C to 16°C), and one outdoor natural temperature curing (in which the air temperature ranges from 4°C to 20°C). Finally, based on the maturity method, the maturity-strength estimation model is obtained by using and analyzing the data collected from the indoor tests. The model is proved with high accuracy based on the validated results obtained from the data of outdoor tests. This research provides technical support for the construction of cement-stabilized macadam in regions with low temperature, which is beneficial in the construction process and quality control.


Coatings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 757 ◽  
Author(s):  
Kim ◽  
Hong ◽  
Han ◽  
Kim

In this study, coating equipment for the effective underwater repair of submerged structures was developed. The tensile bond characteristics of selected epoxy resin coatings were investigated by coating the surface of a specimen using each of the four types of equipment. Using the experimental results, the tensile bond strength and the coating thickness were analyzed according to the type of equipment, coating, and curing time. The results show that the type of coating equipment used had the greatest effect on the measured bond strength and coating thickness of the selected coatings. However, the effect of coating type and curing time on the bond strength and the thickness was observed to be insignificant. Compared with the developed equipment, the surface treatment of the coating was observed to be more effective when using the pre-existing equipment, and thus the bond performance of the coating was improved compared to using the pre-existing equipment. Based on the experimental results, improvements and needs involving the equipment for further research were discussed.


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