scholarly journals Industrial Low-Clinker Precast Elements Using Recycled Aggregates

2020 ◽  
Vol 10 (19) ◽  
pp. 6655
Author(s):  
Carlos Thomas ◽  
Ana I. Cimentada ◽  
Blas Cantero ◽  
Isabel F. Sáez del Bosque ◽  
Juan A. Polanco
Keyword(s):  
Mechanical Properties ◽  
Coarse Aggregate ◽  
Precast Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Slight Reduction ◽  
Construction And Demolition Wastes ◽  
Precast Elements ◽  
The Impact ◽  
Concrete Elements

Increasing amounts of sustainable concretes are being used as society becomes more aware of the environment. This paper attempts to evaluate the properties of precast concrete elements formed with recycled coarse aggregate and low clinker content cement using recycled additions. To this end, six different mix proportions were characterized: a reference concrete; 2 concretes with 25%wt. and 50%wt. substitution of coarse aggregate made using mixed construction and demolition wastes; and others with recycled cement with low clinker content. The compressive strength, the elastic modulus, and the durability indicator decrease with the proportions of recycled aggregate replacing aggregate, and it is accentuated with the incorporation of recycled cement. However, all the precast elements tested show good performance with slight reduction in the mechanical properties. To confirm the appropriate behaviour of New Jersey precast barriers, a test that simulated the impact of a vehicle was carried out.

scholarly journals Mechanical Properties of Geopolymer Concrete Made With Partial Replacement of Coarse Aggregate by Recycled Aggregate

2019 ◽  
Vol 9 (1) ◽  
pp. 2301-2304 ◽  
Keyword(s):  
Mechanical Properties ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Coarse Aggregate ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Geopolymer Concrete ◽  
Recycled Coarse Aggregate ◽  
Coarse Aggregates

Construction is the one the fast growing field in the worldwide. There are many environmental issues connected with the manufacture of OPC, at the same time availability of natural coarse aggregate is getting reduced. Geopolymer binder and recycled aggregates are promising alternatives for OPC and natural coarse aggregates. It is produced by the chemical action of inorganic molecules and made up of Fly Ash, GGBS, fine aggregate, coarse aggregate and an alkaline solution of sodium hydroxide and sodium silicate. 10 M sodium hydroxide and sodium silicate alkali activators are used to synthesis the geopolymer in this study. Recycled aggregates are obtained from the construction demolished waste. The main focus of this work is to find out the mechanical properties of geopolymer concrete of grade G40 when natural coarse aggregate(NCA) is replaced by recycled coarse aggregate in various proportions such as 0%, 10%, 20%, 30%,40% and 50% and also to compare the results of geopolymer concrete made with recycled coarse aggregates(RAGPC) with geopolymer concrete of natural coarse aggregate(GPC) and controlled concrete manufactured with recycled aggregates(RAC) and controlled concrete of natural coarse aggregates(CC) of respective grade. It has been observed that the mechanical properties are enhanced in geopolymer concrete, both in natural coarse aggregate and recycled coarse aggregate up to 30% replacement when it is compared with the same grade of controlled concrete.

scholarly journals Paving with Precast Concrete Made with Recycled Mixed Ceramic Aggregates: A Viable Technical Option for the Valorization of Construction and Demolition Wastes (CDW)

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 24 ◽  
Author(s):  
Andrés Juan-Valdés ◽  
Julia García-González ◽  
Desirée Rodríguez-Robles ◽  
Manuel Guerra-Romero ◽  
Fernando López Gayarre ◽  
...  
Keyword(s):  
Precast Concrete ◽  
Recycled Concrete ◽  
The Other ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Mass Concrete ◽  
Conventional Concrete ◽  
Mixed Aggregates ◽  
Precast Elements ◽  
Mixed Ceramic

This research aimed to prove the feasibility of producing two types of precast elements widely used in construction, such as curbstones and paving blocks, using recycled concrete made with a 50% substitution of the natural gravel by recycled mixed aggregates with a significant ceramic content (>30%). In order to prove the quality of such mass concrete recycled precast elements, two different mixes were used: the first one was a conventional concrete mix provided by Prefabricados de Hormigón Pavimentos Páramo S.L., one of the collaborating companies in this study, and the other was a mixture in which wt 50% of the natural coarse aggregates were substituted for recycled mixed aggregates ceramic (RMAc). This recycled aggregate is a heterogeneous mixture of unbound aggregates, concrete, ceramic, etc., used as a secondary recycled aggregate and commonly produced in a lot of recycling plants in many European countries. This material was supplied by Tecnología y Reciclado S.L., the other collaborating company. Both mixtures were representative in order to establish the comparative behavior between them, taking into account that smaller percentages of replacement of the natural with recycled aggregates will also produce good results. This percentage of substitution represents a high saving of natural resources (gravel) and maintains a balanced behavior of the recycled concrete, so this new material can be considered to be a viable and reliable option for precast mass concrete paving elements. The characterization of the recycled precast elements, covering mechanical, microstructural, and durability properties, showed mostly similar behavior when compared to the analogous industrially-produced pieces made with conventional concrete.

Mechanical Properties of Water-Permeable Concrete Using Coated Recycled Aggregates and Material for Performance Improvement

2013 ◽  
Vol 831 ◽  
pp. 258-262 ◽  
Author(s):  
Young Il Jang ◽  
Yun Yong Kim ◽  
Wan Shin Park
Keyword(s):  
Mechanical Properties ◽  
Silica Fume ◽  
Void Ratio ◽  
Coarse Aggregate ◽  
Plain Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Freeze And Thaw ◽  
Water Permeability Coefficient ◽  
Pva Fiber

The mechanical properties of water-permeable concrete after mixing with coated recycled aggregates, silica fume, and PVA fiber were investigated in this study. Recycled aggregate was coated double-layer and then mixed as the coarse aggregate of water-permeable concrete. As a result, the void ratio, water-permeability coefficient and strength decreased, as compared to concrete with mixed crushed aggregates. When both silica fume and PVA fiber was added, the strength of the water-permeable concrete increased (compressive strength : by 4.3%, flexural strength : by 2.1 times). Also, the freeze and thaw resistance of the water-permeable concrete increased by approximately 44.15% compared to the plain concrete with no added reinforcing element.

scholarly journals Recycled Aggregates from Construction and Demolition Waste in the Manufacture of Urban Pavements

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6605
Author(s):  
Manuel Contreras-Llanes ◽  
Maximina Romero ◽  
Manuel Jesús Gázquez ◽  
Juan Pedro Bolívar
Keyword(s):  
Precast Concrete ◽  
Breaking Load ◽  
Construction And Demolition Waste ◽  
Recycled Aggregates ◽  
Waste Streams ◽  
Demolition Waste ◽  
Class 1 ◽  
Natural Aggregates ◽  
Precast Elements ◽  
Concrete Elements

Construction and Demolition Waste (CDW) is among the largest waste streams in the world. Therefore, within the Circular Economy concept, there is a growing interest in its reuse. The purpose of this work was to study the use of recycled aggregates (RAs) obtained by a specific separation method from CDW, replacing natural aggregates (NAs) in the manufacture of precast concrete elements, such as kerbstones and paver blocks. The physical and technological properties of precast products formulated with RAs were analysed in accordance with current regulations, comparing them with those of commercial products manufactured with NAs. The results indicated that partial or total substitution of NAs by RAs increased the water absorption and apparent porosity values of the precast elements while reducing the bulk density and compressive strength. However, all units manufactured with RAs showed breaking load values higher than the minimum required by EN 1338 and, in some cases, slightly higher average tensile strength values than the reference material. In addition, some of the compositions including RAs gave rise to pieces that, according to their flexural strength, were classified as class 1 and marked S in accordance with EN 1340. According to abrasion resistance, in most cases, the precast elements are classified as Class 4 and I (≤20 mm). Finally, precast concrete produced from RAs satisfies the tolerance requirements for classification as class 3 (≤1.5 kg m−2). Therefore, it could be suitable for use in high pedestrian or traffic areas.

Experimental Study on Strength and other Performance of Solid Concrete Bricks Made from Recycled Coarse Aggregate

2013 ◽  
Vol 357-360 ◽  
pp. 1212-1218 ◽  
Author(s):  
Xi Xi He ◽  
Tao Zhang
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Flexural Strength ◽  
Physical Properties ◽  
Coarse Aggregate ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
The Impact ◽  
The Relationship

Recycled coarse aggregate solid concrete bricks were produced by QTY4-40 brick machine with strength grades of MU15-MU30. Compression and flexural strength of solid recycled coarse aggregate concrete brick were investigated. The impact of recycled aggregate on the solid concrete brick mechanical properties and physical properties was analyzed. The relationship between physical properties and strength, density was discussed.

scholarly journals PERFORMANCE ASSESSMENT OF A SELF-COMPACTING CONCRETE WITH COARSE AND FINE RECYCLED AGGREGATE

2020 ◽  
Author(s):  
Víctor Revilla-Cuesta ◽  
José Antonio Chica Paez ◽  
José Antonio De la Fuente Alonso ◽  
Estibaliz Briz Blanco ◽  
Jorge Hernández Bagages ◽  
...  
Keyword(s):  
Precast Concrete ◽  
Fine Fraction ◽  
Modern Society ◽  
Coarse Fraction ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Self Compacting Concrete ◽  
Limestone Filler ◽  
Hardened State ◽  
Concrete Elements

Environmental protection and more sustainable human activities are two of the main goals faced by modern society. The reuse of wastes, framed within these objectives, directly affects the construction sector. The use of residues enables to reduce the consumption of natural resources and CO2 emissions released into the atmosphere because of the extractive activity, as well as to reduce potential landfills, thus contributing to a circular economy. Accordingly, this paper explores the development of self-compacting concrete made from high-quality recycled aggregates, obtained from the crushing of precast concrete elements. The replacement rates of the natural aggregate by the recycled aggregate were 100% for the coarse fraction and 50% for the fine fraction. Its validity for structural use is analyzed, both fresh and hardened. In addition, the importance of the limestone filler in the fresh rheology of the mentioned concrete and its impact in the hardened state are also evaluated.

scholarly journals Experimental Investigation on Self Compacting Concrete Using Recycled Aggregate

2021 ◽  
pp. 49-53
Author(s):  
N. Uday Kiran ◽  
S. Hanmanthu ◽  
C. Govardhan
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Experimental Work ◽  
Coarse Aggregate ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Self Compacting Concrete ◽  
Recycled Coarse Aggregate

In the present work, an experimental investigation was carried out on self-compacting concrete made with various replacement levels of recycled coarse aggregate. The main aim of the experimental work is to know the suitability and effects of recycled aggregates in SCC. Self-Compacting Concrete is a type of concrete which does not need any kind of vibration or compaction. In the present experimental work, the behaviour of concrete made with recycled aggregates is evaluated and compared with the traditional concrete in which the coarse aggregate is replaced with recycled aggregate by 0%, 50%, and 100% respectively. Mechanical properties of the concrete were evaluated in its fresh and hardened conditions.

scholarly journals Influence of Granite Cutting Waste on Mechanical Properties of Recycled Aggregate Concrete

2021 ◽  
Vol 2070 (1) ◽  
pp. 012165
Author(s):  
Ganesh Naidu Gopu ◽  
M Sri Durga Vara Prasad ◽  
Sugandham Kaumanu ◽  
P Ravi Kumar
Keyword(s):  
Mechanical Properties ◽  
Coarse Aggregate ◽  
Developing Nations ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Fresh Properties ◽  
Normal Concrete ◽  
Aggregate Concrete ◽  
Optimal Values

Abstract Solid waste disposition has been a growing problem in many developed and under-developing nations. Major part of development was constituted by construction and infrastructure; on the contrary these industries also lead to release of carbon dioxide into the atmosphere. To overcome these disadvantages; in this research, recycled aggregates from construction waste and granite cutting waste were adopted as a replacement of coarse aggregate and cement respectively. Mechanical properties of recycled aggregate (RA) concrete are tested by replacing coarse aggregate varying from 0% to 100% with a difference of 25% and cement is replaced with Granite cutting waste (GCW) varying from 0% to 20% with a difference of 5%. Mix designation and fresh properties were also presented. Results were plotted and compared with the normal concrete to predict the most optimal values of the replacement. Mix containing 25% of RA and 15% of GCW replaced has shown a notable difference in strength comparing with the normal aggregate concrete.

scholarly journals Experimental Study on the Mechanical Properties and Compression Size Effect of Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2323
Author(s):  
Yubing Du ◽  
Zhiqing Zhao ◽  
Qiang Xiao ◽  
Feiting Shi ◽  
Jianming Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Size Effect ◽  
Compressive Stress ◽  
Failure Modes ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Substitution Ratio ◽  
The Impact

To explore the basic mechanical properties and size effects of recycled aggregate concrete (RAC) with different substitution ratios of coarse recycled concrete aggregates (CRCAs) to replace natural coarse aggregates (NCA), the failure modes and mechanical parameters of RAC under different loading conditions including compression, splitting tensile resistance and direct shear were compared and analyzed. The conclusions drawn are as follows: the failure mechanisms of concrete with different substitution ratios of CRCAs are similar; with the increase in substitution ratio, the peak compressive stress and peak tensile stress of RAC decrease gradually, the splitting limit displacement decreases, and the splitting tensile modulus slightly increases; with the increase in the concrete cube’s side length, the peak compressive stress of RAC declines gradually, but the integrity after compression is gradually improved; and the increase in the substitution ratio of the recycled aggregate reduces the impact of the size effect on the peak compressive stress of RAC. Furthermore, an influence equation of the coupling effect of the substitution ratio and size effect on the peak compressive stress of RAC was quantitatively established. The research results are of great significance for the engineering application of RAC and the strength selection of RAC structure design.

scholarly journals Discrete Element Simulation Analysis of Biaxial Mechanical Properties of Concrete with Large-Size Recycled Aggregate

2021 ◽  
Vol 13 (13) ◽  
pp. 7498
Author(s):  
Tan Li ◽  
Jianzhuang Xiao
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Strain Curve ◽  
Confining Pressure ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Model ◽  
Large Size

Concrete made with large-size recycled aggregates is a new kind of recycled concrete, where the size of the recycled aggregate used is 25–80 mm, which is generally three times that of conventional aggregate. Thus, its composition and mechanical properties are different from that of conventional recycled concrete and can be applied in large-volume structures. In this study, recycled aggregate generated in two stages with randomly distributed gravels and mortar was used to replace the conventional recycled aggregate model, to observe the internal stress state and cracking of the large-size recycled aggregate. This paper also investigated the mechanical properties, such as the compressive strength, crack morphology, and stress–strain curve, of concrete with large-size recycled aggregates under different confining pressures and recycled aggregate incorporation ratios. Through this research, it was found that when compared with conventional concrete, under the confining pressure, the strength of large-size recycled aggregate concrete did not decrease significantly at the same stress state, moreover, the stiffness was increased. Confining pressure has a significant influence on the strength of large-size recycled aggregate cocrete.

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