Fresh and Mechanical Properties of Sustainable Concrete Using Recycled Aggregates

2019 ◽  
Vol 803 ◽  
pp. 239-245
Author(s):  
Ahmad Khartabil ◽  
Samer Al Martini
Keyword(s):  
Construction Industry ◽  
United Arab Emirates ◽  
Construction Projects ◽  
Rapid Development ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Abu Dhabi ◽  
Natural Aggregates

In the last few decades, the United Arab Emirates (UAE) witnessed rapid development in the construction industry. It was recently emphasized to adopt sustainability practice in all aspects related to construction. The recent sustainable practice that was enforced by Dubai Municipality in construction field is “greening the concrete” by solely replacing the Portland Cement with supplementary cementitious materials (SCMs), such as grand granulated blast furnace slag (GGBS) and fly ash. On the other hand, the use of recycled aggregates can also contribute to the greening of concrete and to the reduction of carbon foot print from the construction industry in the UAE. Consequently, it is significant to study the suitability of local available recycled aggregate and their effect on concrete fresh and hardened properties, in order to expand the current practice. The recycled aggregates, used in this investigation, are obtained from a local recycled aggregates plant in Abu Dhabi using concrete from demolished buildings in Abu Dhabi. The natural aggregates in concrete mixtures were replaced by recycled aggregates with the following percentages: 20%, 40%, 60% and 100%. The concrete parameters investigated are mainly the slump retention, rheology and compressive strength. The results are analyzed to arrive to pertinent conclusions for the utilization of concrete with recycled aggregates in different types of construction projects.

scholarly journals Strength and Durability Studies on Geopolymer Recycled Aggregate Concrete

2018 ◽  
Vol 7 (2.24) ◽  
pp. 370 ◽  
Author(s):  
P Saravanakumar
Keyword(s):  
Construction Industry ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Geopolymer Concrete ◽  
Aggregate Concrete ◽  
Natural Aggregates ◽  
Strength And Durability ◽  
Durability Performance

This paper aims to study the engineering and durability properties of fly ash-based geopolymer recycled aggregate concrete and the results were presented in this paper. The addition of recycled coarse aggregate (RCA) retrieved from construction and demolition(C&D) wastes showed promising function in construction industry as an alternative to natural aggregates. It conserves enormous quantities of natural resources and reduces the space required for the landfill disposal of C&D wastes. In this study an increment of 25% partial replacements by weight of natural aggregates with recycled aggregates in geopolymer concrete up to 100% replacements were studied. The concrete containing virgin aggregate and ordinary Portland cement was consider as control concrete and the results of geopolymer recycled aggregate concrete (GP-RAC)  were compared with this. The fresh and mechanical properties of all the above four concrete mixes has been investigated. Results indicated that workability of geopolymer concrete decreases than control concrete and it took more than 24 hours to set. Geo polymer based recycled aggregate concrete exhibits better strength and durability performance than ordinary recycled aggregate concrete.  

Carbonation Resistance of Sustainable Concrete Using Recycled Aggregate and Supplementary Cementitious Materials

2019 ◽  
Vol 803 ◽  
pp. 246-252 ◽  
Author(s):  
Ahmad Khartabil ◽  
Samer Al Martini
Keyword(s):  
Portland Cement ◽  
Construction Industry ◽  
Cementitious Materials ◽  
Chloride Penetration ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregate ◽  
Concrete Mixture ◽  
Sustainable Concrete ◽  
Concrete Mixtures ◽  
Carbonation Resistance

Green concrete is a recent sustainable practice in UAE that was enforced by Dubai Municipality in construction field within the emirate of Dubai to reduce the carbon foot print in construction industry and to increase the durability of the structures. This led the construction industry to reduce the usage of ordinary portland cement by replacing it with supplementary cementitious materials (SCMs) such as Grand Granulated Blast Furnace Slag (GGBS) and flyash (FA). Incorporating GGBS or FA in concrete mixtures can improve durability parameters of hardened concrete, such as resistance to water permeability, reduced water absorption and chloride penetration. This ultimately increases the structure’s service life by increasing the threshold of concrete mixture for chloride induced corrosion. On the other hand, carbonation induced corrosion to concrete is usually being ignored or forgotten generally, due its usual slow rate ingression in plain portland cement concrete mixtures. Several studies showed that incorporating some types of SCM – especially at high percentage - can reduce the concrete resistance to carbonation. Additionally and for concrete with recycled aggregate, carbonation investigation should be taken into consideration. This is since recycled aggregates are reused aggregates that are extracted from demolished structures and buildings which were already subjected to different environmental exposures and deteriorations. Unlike chloride penetration, there is no direct ASTM standard test to anticipate the concrete mixture resistance to carbonation at early ages. In this study, concrete mixtures with flyash and different recycled aggregate replacement percentages are investigated for carbonation resistance in accelerated proposed method, considering concrete mixtures’ key parameters like water-cement ratio, and total cement content. The results are analyzed to arrive to pertinent conclusions for the best utilization of sustainable concrete for carbonation resistance.

scholarly journals Concretes with binary mixtures of artificial pozzolans and concrete demolition waste

2020 ◽  
Vol 20 (4) ◽  
pp. 177-188
Author(s):  
Cristian Jonathan Franco de Lima ◽  
Francisco Roger Carneiro Ribeiro ◽  
Geraldo Cechella Isaia ◽  
Mauricio Mancio
Keyword(s):  
Binary Mixtures ◽  
Modulus Of Elasticity ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
Durability Test ◽  
Concrete Mixtures ◽  
Pozzolanic Materials

Abstract The objective of this study is to analyse the use of binary mixtures of pozzolanic materials and concrete demolition waste in concrete mixtures, especially the resulting mechanical properties and durability. A total of ten concrete formulations were produced distinguishing them in different types using different Portland cements, different artificial pozzolans and coarse aggregates from concrete demolition. The particular properties of each formulation were verified by testing the axial compressive strength, longitudinal modulus of elasticity and penetration of chloride under immersion. Substitutions were of 15% w.t. and 30% w.t. natural coarse aggregate substituted with concrete demolition waste and, in the case of binary mixtures, additional 25% w.t. of the binder agglomerate substituted with rice husk ash or fly ash. Results showed that the final strength to axial compression and modulus of elasticity of concrete mixtures were negatively affected by utilising demolition waste, but this effect was balanced by adding supplementary cementitious materials. Regarding the durability test, it was found that the lowest coefficients occurred in the mixtures using CP V-ARI, together with artificial pozzolans, in mixtures with 15% w.t. substitution of natural aggregate with recycled aggregate. It was concluded that using recycled aggregates in concrete is viable but conditioned to the concomitant use of pozzolanic materials.

scholarly journals Discussion on the Application of New Photovoltaic Energy in Building Electrical Energy Saving

2020 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Qian Yang
Keyword(s):  
Energy Conservation ◽  
Construction Industry ◽  
Construction Projects ◽  
Negative Impact ◽  
Rapid Development ◽  
Social Economy ◽  
Green Building ◽  
Electrical Energy ◽  
New Energy

<p>With the rapid development of social economy, the demand for new energy is also increasing, and then the problem of large consumption also has a negative impact on the development of the construction industry. Under the concept of green building, the design and construction units pay more attention to energy conservation and environmental protection, so they actively use photovoltaic new energy in the field of electrical energy conservation of construction projects, so as to improve people's quality of life. Starting from the principles and characteristics of building electrical energy conservation, this paper discusses the methods of building electrical energy conservation, and analyzes how to use photovoltaic new energy in the field of building electrical energy conservation, hoping to better practice the concept of energy conservation.</p>

scholarly journals The Potentials of Iron and Steel Slags as Supplementary Cementitious Materials in the Nigerian Construction Industry: A Review

2018 ◽  
Vol 2 (2) ◽  
pp. 208-218
Author(s):  
O. R. Ogirigbo ◽  
J. O. Ukpata ◽  
I. Inerhunwa
Keyword(s):  
Portland Cement ◽  
Construction Industry ◽  
Waste Product ◽  
Steel Production ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Iron And Steel ◽  
Tropical Environments ◽  
Iron And Steel Production

Ground Granulated Blast Furnace Slag (GGBS) is a type of Supplementary Cementitious Material (SCM) that is currently being used extensively in the global construction industry. SCMs are cheaper than Portland cement, help to improve certain properties of concrete and also help to reduce the environmental footprint associated with the production of Portland cement. GGBS is readily available in most parts of the world as a waste product from iron and steel production. However, its use as a SCM in some countries has not been fully maximized. This is primarily because of lack of documented studies on the properties of GGBS that influences its suitability as a SCM, especially in tropical environments. This paper reviewed the use of GGBS as a SCM for the partial replacement of Portland cement, with particular emphasis on its potential use in tropical warm environments such as Nigeria and other similar countries.

scholarly journals Sustainability of Construction Aggregates in Kuwait

2019 ◽  
Vol 2 (4) ◽  
pp. 406
Author(s):  
Sharifa Al-Fadala
Keyword(s):  
Construction Industry ◽  
United Arab Emirates ◽  
Coarse Aggregate ◽  
Waste Utilization ◽  
Recycled Aggregates ◽  
Environmental Pressures ◽  
Coarse Aggregates ◽  
Constituent Material ◽  
Construction And Demolition Wastes ◽  
Local Construction

Kuwait is facing a current construction boom with projects worth of more than USD188bn. The huge infrastructure spending plan of Kuwait is reflected with a growing demand of concrete as concrete is the most commonly used building material in the local construction. At the present, the quarrying of coarse aggregate which is a main concrete constituent material is banned in Kuwait since 1997 and construction industry depends on the imported coarse aggregates from neighbouring sources such as United Arab Emirates and Iran. Kuwait is also interested in challenging the growing concern of an effective environmental management of water, land and atmosphere to achieve a sustainable civilization. The increasingly environmental pressures coupled with the limited available economical resources are causing the decision making authorities to consider the practice of recycling and waste utilization. This paper presents Kuwait Institute for Scientific Research (KISR) efforts to investigate sustainable sources of coarse aggregate for construction industry from waste. The first sustainable source investigated is the production of synthetic lightweight aggregates utilizing combinations of argillaceous indigenous and waste materials, and the second is recycled aggregates from construction and demolition wastes. The potential of the two sustainable sources of construction aggregates are presented and the needed steps for real industrial application are addressed.

scholarly journals Sulfate Resistance of Recycled Aggregate Concrete with GGBS and Fly Ash-Based Geopolymer

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1247 ◽  
Author(s):  
Jianhe Xie ◽  
Jianbai Zhao ◽  
Junjie Wang ◽  
Chonghao Wang ◽  
Peiyan Huang ◽  
...  
Keyword(s):  
Fly Ash ◽  
Construction Projects ◽  
High Performance ◽  
High Performance Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Concrete ◽  
Sulfate Resistance ◽  
Coarse Aggregates

There is a constant drive for the development of ultra-high-performance concrete using modern green engineering technologies. These concretes have to exhibit enhanced durability and incorporate energy-saving and environment-friendly functions. The object of this work was to develop a green concrete with an improved sulfate resistance. In this new type of concrete, recycled aggregates from construction and demolition (C&D) waste were used as coarse aggregates, and granulated blast furnace slag (GGBS) and fly ash-based geopolymer were used to totally replace the cement in concrete. This study focused on the sulfate resistance of this geopolymer recycled aggregate concrete (GRAC). A series of measurements including compression, X-ray diffraction (XRD), and scanning electron microscopy (SEM) tests were conducted to investigate the physical properties and hydration mechanisms of the GRAC after different exposure cycles in a sulfate environment. The results indicate that the GRAC with a higher content of GGBS had a lower mass loss and a higher residual compressive strength after the sulfate exposure. The proposed GRACs, showing an excellent sulfate resistance, can be used in construction projects in sulfate environments and hence can reduce the need for cement as well as the disposal of C&D wastes.

scholarly journals A Review on Alkali-Silica Reaction Evolution in Recycled Aggregate Concrete

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2625 ◽  
Author(s):  
Miguel Barreto Santos ◽  
Jorge De Brito ◽  
António Santos Silva
Keyword(s):  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Mitigation Measures ◽  
Alkali Silica Reaction ◽  
Aggregate Concrete ◽  
Reactive Silica ◽  
Natural Aggregates ◽  
Exposure Conditions ◽  
Lack Of Knowledge

Alkali-silica reaction (ASR) is one of the major degradation causes of concrete. This highly deleterious reaction has aroused the attention of researchers, in order to develop methodologies for its prevention and mitigation, but despite the efforts made, there is still no efficient cure to control its expansive consequences. The incorporation of recycled aggregates in concrete raises several ASR issues, mainly due to the difficult control of the source concrete reactivity level and the lack of knowledge on ASR’s evolution in new recycled aggregate concrete. This paper reviews several research works on ASR in concrete with recycled aggregates, and the main findings are presented in order to contribute to the knowledge and discussion of ASR in recycled aggregate concrete. It has been observed that age, exposure conditions, crushing and the heterogeneity source can influence the alkalis and reactive silica contents in the recycled aggregates. The use of low contents of highly reactive recycled aggregates as a replacement for natural aggregates can be done without an increase in expansion of concrete. ASR expansion tests and ASR mitigation measures need to be further researched to incorporate a higher content of recycled aggregates.

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