The Durability of Fine Recycled Aggregate Concrete

2017 ◽  
Vol 1144 ◽  
pp. 59-64 ◽  
Author(s):  
Magdaléna Šefflová ◽  
Tereza Pavlů
Keyword(s):  
Compressive Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Carbonation Depth ◽  
Natural Sand ◽  
Conventional Concrete ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Concrete Mixtures

This paper is focused on the durability of recycled aggregate (FRA) concrete. The durability of FRA concrete is connected with many uncertainties and doubts. This paper presents results of long-term of compressive strength, freeze – thaw resistance and carbonation depth of FRA concrete. The FRA was originated from crushed old concrete structures. There were prepared a total four concrete mixture. The first mixture was reference with natural sand. In other concrete mixtures, natural sand was replaced by the FRA in various replacement ratios, specifically 10 %, 20 % and 30 %. All prepared concrete mixtures were designated with the same parameters for clear comparison. It is possible to say that according to the durability, the FRA concrete is possible to used in the same applications as conventional concrete. However it is necessary to verify this results.

The Carbonation Depth of Fine Recycled Aggregate Concrete

2016 ◽  
Vol 722 ◽  
pp. 228-232 ◽  
Author(s):  
Magdaléna Šefflová ◽  
Tereza Pavlů
Keyword(s):  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Partial Replacement ◽  
Concrete Durability ◽  
Test Results ◽  
Carbonation Depth ◽  
Natural Sand ◽  
Conventional Concrete ◽  
Concrete Mixtures ◽  
Carbonation Resistance

This paper is focused on carbonation resistance of fine recycled aggregate (FRA) concrete. Durability of FRA concrete is connected with uncertainties and doubts. One of the most unknown aspects of FRA cocnrete is carbonation resistance. This paper presents results of carbonation depth of FRA concrete. The FRA was originated from crushed construction and demolition (C&D) waste. There were prepared a total four concrete mixture. The first mixture was reference, did not include the FRA. In other concrete mixtures, natural sand was replaced by the FRA in various replacement ratios, specifically 10%, 20% and 30%. All prepared concrete mixtures were designated with the same parameters for clear comparison. From the test results it is possible to say that the use of the FRA as partial replacement of natural sand in concrete influences carbonation resistance of concrete. The carbonation depth was higher for concrete samples with the use of FRA. However it is possible to say that according to the carbonation resistance, the FRA concrete is possible to be used in the same applications as conventional concrete but it is necessary to verify this results.

The Properties of Fine Recycled Aggregate Concrete Containing Recycled Bricks from Construction and Demolition Waste

2018 ◽  
Vol 760 ◽  
pp. 193-198 ◽  
Author(s):  
Kristina Fořtová ◽  
Tereza Pavlů
Keyword(s):  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Demolition Waste ◽  
Natural Sand ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Recycled Fine Aggregate

This paper presents research results of recycled fine aggregate concrete testing. The main aim of this contribution is verification of properties of fine aggregate concrete with partial replacement of fine natural aggregate by recycled masonry aggregate originated from construction and demolition waste. The influence of partial replacement of natural sand to mechanical properties and freeze-thaw resistance is described. The compressive strength and flexural strength were tested at the age of 28 and 60 days and after 25, 50, 75 and 100 freeze-thaw cycles. Partial replacement of natural sand was 0, 25 and 50 % for all these tests. Prismatic specimens were examined.

scholarly journals Compressive Strength Study on the Freeze-thaw Resistance of Recycled Aggregate Concrete Members

2017 ◽  
Vol 11 (1) ◽  
pp. 270-280 ◽  
Author(s):  
Haicheng Niu ◽  
Yonggui Wang ◽  
Xianggang Zhang ◽  
Xiaojing Yin
Keyword(s):  
Compressive Strength ◽  
Mass Loss ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Fine Aggregate ◽  
Replacement Rate ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Surface Scaling

Introduction: Freeze-thaw resistance of recycled aggregate concrete with partial or total replacement of recycled aggregate compared with that of natural aggregate concrete was investigated in this paper. Method: Ninety specimens were fabricated to study the influence of different recycled aggregate replacement ratios on the surface scaling, mass loss, and residual compressive strength after 100 freeze-thaw cycles. Results: The experiment results indicate that the type of recycled aggregate and its replacement ratio have significant effects on the freeze-thaw performance. The cubic compressive strength of recycled aggregate concrete is overall slightly lower than that of normal concrete. After 100 freeze-thaw cycles, the compressive strength decreases and the reduction extent increases with increasing replacement rate of recycled aggregate. The surface scaling of reinforced recycled concrete prisms tends to be more severe with the increase of freeze-thaw cycles. Conclusion: Furthermore, a notable rise in mass loss and the bearing capacity loss is also found as the substitution ratio increases. Under the same replacement rate, recycled fine aggregate causes more negative effects on the freeze-thaw resistance than recycled coarse aggregate.

scholarly journals Effect of Freeze–Thaw Cycles on Carbonation Behavior of Three Generations of Repeatedly Recycled Aggregate Concrete

2021 ◽  
Vol 11 (6) ◽  
pp. 2643
Author(s):  
Hui Liu ◽  
Minqi Hua ◽  
Pinghua Zhu ◽  
Chunhong Chen ◽  
Xinjie Wang ◽  
...  
Keyword(s):  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Rate ◽  
Carbonation Depth ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
The Third ◽  
Three Generations ◽  
Carbonation Resistance ◽  
Multiple Recycling

Multiple recycling of waste concrete has attracted widespread attention. This study presented the carbonation behavior of repeatedly recycled aggregate concrete (RRAC) used in a micro-frozen region. The effects of freeze–thaw cycles on the carbonation depth of three generations of RRAC with 25%, 75%, and 100% of replacement rate were evaluated. All RRAC specimens after different numbers of freeze–thaw cycles were rapidly carbonated for 28 d indoors to test the carbonation resistance of concrete. The results suggested that the carbonation depth of RRAC subjected to freeze–thaw cycles is higher than that in the non-freeze–thaw condition. This is because the freeze–thaw damages cause the internal structure of RRAC to become porous and and prone to cracking, thus providing convenient channels for CO2 to react with the alkali in the cementitious materials. With the growth of replacement rate or recycling number, RRAC reveals serious freeze–thaw damage and inferior carbonation resistance, which is due to the continuous deterioration repeatedly recycled concrete aggregate (RRCA) quality. However, when the replacement rate was 25%, the carbonation depth for the third generation of RAC was comparable to the second generation of RAC at a 75% replacement rate, and even the first generation of 100% RAC. To ensure better carbonation resistance durability of multiple recycling RAC, the low replacement rate of RRCA should be considered. For the third generation of RAC with the 100% replacement rate, its highest carbonation depth after freeze–thaw cycles was 9.16 mm, which still met the design requirements for structural use in a micro-frozen region. This indicates that it is feasible for three generations of RRAC to be used in the micro-frozen environment and that RRAC has great engineering application potential and promotional value.

scholarly journals Study the effect of vibration mixing on the performances of full replacement recycled aggregate concrete

2021 ◽  
Vol 276 ◽  
pp. 02027
Author(s):  
Taotao Li
Keyword(s):  
Compressive Strength ◽  
Solid Waste ◽  
Building Materials ◽  
Engineering Application ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Carbonation Depth ◽  
Aggregate Concrete ◽  
Natural Aggregate ◽  
Splitting Strength

It is an urgent problem that the construction solid waste is difficult to be treated, and its recycling provides a way for its treatment. The quality of construction solid waste recycled aggregate is lower than that of natural aggregate, which limits its extensive application in building materials. In order to provide a new method for engineering application of recycled aggregate concrete, the influence of vibration mixing on the performances of full replacement recycled aggregate concrete were studied. The performance indexes of recycled aggregate concrete under ordinary mixing and vibration mixing were compared and analyzed. The experimental results show that compared with natural aggregate concrete, the slump of full replacement recycled aggregate concrete decreased by 58.8%, and 7d and 28d compressive strength decreased by 12.9% and 16.1%, and the splitting strength decreased by 30.6% and 20.1%, and the carbonation depth decreased by 91.5%; Compared with natural aggregate concrete using ordinary mixing, the slump of full replacement recycled aggregate concrete using vibration mixing decreased by 50.9%, the 7d and 28d compressive strength decreased by 6.9% and 10.9%, and the splitting strength decreased by 16.9% and 12.4%, and the 28d carbonation depth decreased by 34.9%. The results show that compared with ordinary mixing, vibration mixing can improve the performance of recycled aggregate concrete, which provides a reference for engineering application.

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

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.

The Comparison of Properties of Fine Recycled Aggregate Concrete from Different Sources of Recycled Aggregate

2018 ◽  
Vol 760 ◽  
pp. 176-183 ◽  
Author(s):  
Tereza Pavlů
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Concrete Properties ◽  
Different Sources

The main aim of this contribution is comparison the properties of fine aggregate concrete with partial replacement of sand by fine recycled aggregate. The fine recycled aggregate originated from two different sources. The main topic of this article is the study of influence of the origin of FRA to fine aggregate concrete properties. The compressive strength, flexural strength and freeze-thaw resistance were tested. The mechanical properties and weight were examined after 28 and 60 days and after 25, 50, 75 and 100 cycles of freeze-thaw. Partial replacement of sand was 25 and 50 % for all these tests. The properties were investigated by using prismatic specimens.

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