Experimental Studies on the Homogeneity and Compressive Strength Prediction of Recycled Aggregate Concrete (RAC) Using Ultrasonic Pulse Velocity (UPV)

This study examines the hydration–mechanical–autogenous shrinkage–durability–sustainability properties of ternary composites with limestone filler (LF) and ground-granulated blast furnace slag (BFS). Four mixtures were prepared with a water/binder ratio of 0.3 and different replacement ratios varying from 0 to 45%. Multiple experimental studies were performed at various ages. The experimental results are summarized as follows: (1) As the replacement levels increased, compressive strength and autogenous shrinkage (AS) decreased, and this relationship was linear. (2) As the replacement levels increased, cumulative hydration heat decreased. At the age of 3 and 7 days, there was a linear relationship between compressive strength and cumulative hydration heat. (3) Out of all mixtures, the ultrasonic pulse velocity (UPV) and electrical resistivity exhibited a rapid increase in the early stages and tended to slow down in the latter stages. There was a crossover of UPV among various specimens. In the later stages, the electrical resistivity of ternary composite specimens was higher than plain specimens. (4) X-ray diffraction (XRD) results showed that LF and BFS have a synergistic effect. (5) With increasing replacement ratios, the CO2 emissions per unit strength reduced, indicating the sustainability of ternary composites.

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Estimation of Compressive Strength of Recycled Aggregate High Strength Concrete Using Ultrasonic Pulse Velocity

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.605.147 ◽

2014 ◽

Vol 605 ◽

pp. 147-150

Author(s):

Seong Uk Hong ◽

Seung Hun Kim ◽

Yong Taeg Lee

Keyword(s):

Compressive Strength ◽

High Strength Concrete ◽

Coarse Aggregate ◽

High Strength ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Recycled Aggregate ◽

Strength Concrete ◽

Recycled Coarse Aggregate

This study used the ultrasonic pulse velocity method, one of the non-destructive test methods that does not damage the building for maintenance of to-be-constructed concrete structures using recycled aggregates in order to estimate the compressive strength of high strength concrete structure using recycled coarse aggregate and provide elementary resources for technological establishment of ultrasonic pulse velocity method. 200 test pieces of high strength concrete 40, 50MPa using recycled coarse aggregate were manufactured by replacement rates (0, 30, 50, 100%) and age (1, 7, 28, 180days), and air curing was executed to measure compressive strength and wave velocity. As the result of compressive strength measurement, the one with age of 180day and design strength of 40MPa was 43.69MPa, recycled coarse aggregate replacement rate of 30% 50% 100% were 42.82, 41.22, 37.35MPa, and 50MPa was 52.50MPa, recycled coarse aggregate replacement rate of 30% 50% 100% were 49.02, 46.66, 45.30MPa, and while it could be seen that the test piece substituted with recycled aggregate was found to have lower strength than the test piece with natural aggregate only, but it still reached the design strength to a degree. The correlation of compressive strength and ultrasonic pulse velocity was found and regression analysis was conducted. The estimation formula for compressive strength of high strength concrete using recycled coarse aggregate was found to be Fc=0.069Vp4.05, R2=0.66

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The Research of Green High Performance Recycled Construct Materials

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.71-78.4471 ◽

2011 ◽

Vol 71-78 ◽

pp. 4471-4475

Author(s):

Xiao Xiong Zha ◽

Kai Zhang

Keyword(s):

Compressive Strength ◽

High Performance ◽

Experimental Studies ◽

Recycled Concrete ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Aggregate Concrete ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Large Water

Recycled concrete aggregates have large porosity, large water absorption and high crush index. Mechanical properties of recycled concrete aggregates could be improved by adding activated water instead of ordinary water. On the basis of the experimental studies, this paper analyzes the influences on recycled concrete compression strength when using activated water. There are many different factors such as the kinds and amounts of alkali and the water slag ratio affecting the compressive strength of recycle geopolymer. The results show that activated water has a high enhancement on compressive strength of recycled aggregate concrete, and the highest compressive strength of recycled geopolymer is 57.3MPa.

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Correlation between the porosity and ultrasonic pulse velocity of recycled aggregate concrete at different saturation levels

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2016-0449 ◽

2017 ◽

Vol 44 (11) ◽

pp. 911-917 ◽

Cited By ~ 4

Author(s):

Kahina Haddad ◽

Ourdia Haddad ◽

Salima Aggoun ◽

Salah Kaci

Keyword(s):

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Recycled Concrete ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Concrete Aggregate ◽

Saturation State ◽

Pore Connectivity ◽

Accessible Porosity

In this work, an ultrasonic technique was developed to study the porosity and pore connectivity of recycled aggregate concretes (RACs) and to elucidate the correlations between the ultrasonic pulse velocity (UPV), recycled concrete aggregate (RCA) content, and water-accessible porosity of the resulting concrete. To estimate the changes in the degree of connectivity of the concrete pores with the amount of RCA substituted, the concrete specimens were examined at different saturation levels. The correlations between the amounts of RCA used, the UPV, and the saturation state could be determined. It was observed that the pore connectivity of the concretes increased with the amount of RCA substituted, which, in turn, increased their open porosity. These findings may facilitate the use of UPV for the estimation of open porosities of RACs at different saturation levels.

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Setting time and compressive strength prediction model of concrete by nondestructive ultrasonic pulse velocity testing at early age

Construction and Building Materials ◽

10.1016/j.conbuildmat.2020.119027 ◽

2020 ◽

Vol 252 ◽

pp. 119027 ◽

Cited By ~ 2

Author(s):

Taegyu Lee ◽

Jaehyun Lee

Keyword(s):

Compressive Strength ◽

Prediction Model ◽

Setting Time ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Strength Prediction ◽

Early Age

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Recycled Aggregates Concrete Compressive Strength Prediction Using Artificial Neural Networks (ANNs)

Infrastructures ◽

10.3390/infrastructures6020017 ◽

2021 ◽

Vol 6 (2) ◽

pp. 17

Author(s):

Mohamad Ali Ridho B K A ◽

Chayut Ngamkhanong ◽

Yubin Wu ◽

Sakdirat Kaewunruen

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Strength Prediction ◽

Concrete Compressive Strength ◽

Conventional Concrete ◽

Aggregate Concrete ◽

Ann Models

The recycled aggregate is an alternative with great potential to replace the conventional concrete alongside with other benefits such as minimising the usage of natural resources in exploitation to produce new conventional concrete. Eventually, this will lead to reducing the construction waste, carbon footprints and energy consumption. This paper aims to study the recycled aggregate concrete compressive strength using Artificial Neural Network (ANN) which has been proven to be a powerful tool for use in predicting the mechanical properties of concrete. Three different ANN models where 1 hidden layer with 50 number of neurons, 2 hidden layers with (50 10) number of neurons and 2 hidden layers (modified activation function) with (60 3) number of neurons are constructed with the aid of Levenberg-Marquardt (LM) algorithm, trained and tested using 1030 datasets collected from related literature. The 8 input parameters such as cement, blast furnace slag, fly ash, water, superplasticizer, coarse aggregate, fine aggregate, and age are used in training the ANN models. The number of hidden layers, number of neurons and type of algorithm affect the prediction accuracy. The predicted recycled aggregates compressive strength shows the compositions of the admixtures such as binders, water–cement ratio and blast furnace–fly ash ratio greatly affect the recycled aggregates mechanical properties. The results show that the compressive strength prediction of the recycled aggregate concrete is predictable with a very high accuracy using the proposed ANN-based model. The proposed ANN-based model can be used further for optimising the proportion of waste material and other ingredients for different targets of concrete compressive strength.

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Characteristics of Preplaced Aggregate Concrete Fabricated with Alkali-Activated Slag/Fly Ash Cements

Materials ◽

10.3390/ma14030591 ◽

2021 ◽

Vol 14 (3) ◽

pp. 591

Author(s):

Salman Siddique ◽

Hyeju Kim ◽

Hyemin Son ◽

Jeong Gook Jang

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Water Absorption ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Cement Grout ◽

Aggregate Concrete ◽

Alkali Activated ◽

Alkali Activated Cement

This study assesses the characteristics of preplaced aggregate concrete prepared with alkali-activated cement grout as an adhesive binder. Various binary blends of slag and fly ash without fine aggregate as a filler material were considered along with different solution-to-solid ratios. The properties of fresh and hardened grout along with the properties of hardened preplaced concrete were investigated, as were the compressive strength, ultrasonic pulse velocity, density, water absorption and total voids of the preplaced concrete. The results indicated that alkali-activated cement grout has better flowability characteristics and compressive strength than conventional cement grout. As a result, the mechanical performance of the preplaced aggregate concrete was significantly improved. The results pertaining to the water absorption and porosity revealed that the alkali-activated preplaced aggregate concrete is more resistant to water permeation. The filling capacity based on the ultrasonic pulse velocity value is discussed to comment on the wrapping ability of alkali-activated cement grout.

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Estimation of Compressive Strength of High-Strength Concrete with Recycled Aggregate Using Ultrasonic Pulse Velocity Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.680.226 ◽

2013 ◽

Vol 680 ◽

pp. 226-229 ◽

Cited By ~ 3

Author(s):

Young Sang Cho ◽

Sang Ki Baek ◽

Yong Taeg Lee ◽

Seung Hun Kim ◽

Jun Ho Park ◽

...

Keyword(s):

Compressive Strength ◽

High Strength Concrete ◽

Coarse Aggregate ◽

High Strength ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Recycled Aggregate ◽

Strength Concrete ◽

Recycled Coarse Aggregate

Recently, many structures which were built about 30 years ago are watched by reconstruction. Demolished concrete is occurred in the process and these quantity increase about 10% more than the preceding year. Although the government have promoted to use recycled coarse aggregate, many registered architects have not use it, because natural aggregate is still cheaper than recycled coarse aggregate's price and they have question about quality of recycled coarse aggregate. In addition, there are no grounds to rely upon compressive strength and ultrasonic pulse velocity method of recycled coarse aggregate when it is used to high strength concrete. In this paper, bases will be adduced to verify applicative possibility of estimation of compressive strength of high-strength concrete with recycled aggregate using ultrasonic pulse velocity method. For this, compressive strength and ultrasonic pulse velocity method tests of 240 high strength concrete specimens with recycled coarse aggregate were performed, and the high strength concrete specimens were tested within the limits such as compressive strength and ultrasonic pulse velocity

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Performance Degradation and Microscopic Analysis of Lightweight Aggregate Concrete after Exposure to High Temperature

Materials ◽

10.3390/ma13071566 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1566 ◽

Cited By ~ 2

Author(s):

Weijing Yao ◽

Jianyong Pang ◽

Yushan Liu

Keyword(s):

Compressive Strength ◽

High Temperature ◽

Lightweight Aggregate ◽

Strength Loss ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Lightweight Aggregate Concrete ◽

Aggregate Concrete ◽

Damage Degree

This study analyses the deterioration of mechanical properties in lightweight concrete after exposure to room temperature (20 °C) and high temperature, i.e., up to 1000 °C, including changes in visual appearance, loss of mass, and compressive strength. All-lightweight shale ceramsite aggregate concrete (ALWAC) and semi-lightweight shale ceramsite aggregate concrete (SLWAC) are prepared using an absolute volume method to analyse the relationships between relative ultrasonic pulse velocity, loss rate of compressive strength, damage degree, and temperature levels. Our results show that, under high temperature, the lightweight aggregate ceramsite concrete performs better compared to normal concrete. After exposure to 1000 °C, the ALWAC shows a strength loss of no more than 80%, while the normal concrete loses its bearing capacity, with a similar strength loss as the SLWAC. Furthermore, the relative ultrasonic pulse velocity and damage degree are used to evaluate the effects of high temperature on the concretes, including the voids and cracks on the surface and inside of the specimens, which induces the deterioration of mechanical properties and contributes to the thermal decomposition of the cementing system and the loss of cohesion at the aggregate interface. Based on internal structure analyses, the results from this study confirm that the lightweight aggregate concrete shows a high residual compressive strength after exposure to the high temperature.

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