Concrete with recycled aggregates as urban sustainability project

International Journal for Research in Applied Science and Engineering Technology, 2017

This experimental investigation is performed to investigate the used of demolished concrete for construction in concrete material. Demolished concrete occupies a large space and hence it's disposal is very important. Only a small quantity of this waste is recycled for beneficial use. The present investigation is focused on use of demolished concrete in order to reduce construction cost and resolve housing problems faced by the low income communities of the world. The demolished waste of concrete is segregated with the aid of sieving to achieve required sizes of aggregate various tests were conducted to determine the mixture properties of material before producing a new concrete. This investigation explained that the demolished concrete might be received from construction site used for making good quality concrete. The investigational analysis has been optimized to estimate the cause of compressive strength of recycled concrete for the study at 7 th and 28 th days. The compression strength concrete thus, examined was compared with strength of conventional concrete. The outcomes of investigation explained the compressive strength of concrete up to 50% coarse aggregate substitution with demolished concrete at the end of 28 days has been achieve to be comparable to the conventional concrete.

Proceedings of the International Conference on Emerging Trends in Engineering & Technology (IConETech-2020), 2020

The recent increase in structural developments worldwide, has given rise to the consumption of natural aggregates and energy hence generating a vast amount of construction and demolition waste. Natural aggregates occupy 60-75 percent in volume of the concrete matrix. It is beneficial to recycle construction and demolition waste, for construction activities. One such material retained from construction sites is waste concrete, which can be used to produce recycled concrete aggregates (RCAs). Recycling waste concrete produces a substitute to natural aggregates and preserves the environment by reducing waste disposal at landfills and conserving energy. The use of recycled concrete aggregates has piqued the interest of many researchers by utilization of a full or partial substitution to that of natural aggregates in concrete mixtures. Over the last decade, a significant volume of literature has been published discussing the properties and microstructure of recycled concrete aggregates and its response when used in a new concrete mix. Within this paper a brief history of RCAs is outlined together with statistics on the quantity of concrete waste produced, recycled and its practical applications. A comparison between the RCA and natural aggregate properties are discussed on a microscopic level, such as the density and water absorption capacities. Further to this, a summary of the mechanical and durability parameters are discussed such as compressive, tensile and flexural strengths together with chloride ion penetration. Several pre-treatment methods such as: acid treatment and the use of fine mineral fillers are also discussed. Finally, the conclusions and gaps are stated.

Worldwide, cities generate about 1.3 billion Tonnes of solid waste per year. Building materials account for about half of all materials used and about half the solid waste generated worldwide. The waste, generated in the construction, maintenance, repair and disposal phases of a building, is called Construction and Demolition (C&D) Waste. Management of C&D waste is a problem faced not only in India but by the global community and quantum of waste produced occupies a huge fraction of the total solid waste generation by mass. Furthermore, a continued environmental awareness instigates the pressure for reuse of construction materials instead of classifying them as waste materials. Using construction waste material as an aggregate for developing new concrete product is technically viable and may, in some circumstances, be environmentally beneficial. The recent government initiative to stop sand mining insists the need to recycle, reuse and substitute natural aggregates in order to ensure environmental sustainability. This research work aims at making one such experiment where recycled aggregates are produced from C&D waste thus paves a way, for the effective management of concrete debris. The concrete waste was collected from the waste yard in the college campus, segregated, crushed in jaw crusher, sieved, washed and used for concreting for a mix proportion of M25, as a replacement for natural course aggregates in proportions of 0%, 30%, 60% and 100%. On testing, the compressive strength was found to be increasing and split tensile strength and flexural strength were observed to be nearly equal to that of normal concrete mix. Therefore, use of recycled concrete aggregate showed acceptable performance with respect to mechanical properties. The recycled aggregates obtained from waste concrete are more angular and have higher absorption and specific gravity than natural coarse aggregates and it resulted in increased strength and improved load carrying capacity. However, further studies to determine the effect on durability and improvement on workability are necessary.

Conference Paper, 2007

Some countries started to recycle concrete material in order to reuse it in structural or other issues. Some of them, like Germany, Australia and Canada have established their own recommendation guide for recycling concrete. This recycling consists of crushing old concrete into aggregates, and then processing it into new mixture using the recycled aggregates with specified sizes. The aim of this recycling is to save nature from deforestation and dryness, by reducing the need to gravel and so the quarries work, and also to economize the waste management. The present research work consists of an experimental study treating the impact of using recycled aggregates on the concrete behavior and on the country’s economy. We are especially interested in determining the best composition for the new mixture of concrete resulting from reusing different types of recycled aggregates. Different types of tests have been done depending on the aggregates sizes, their origin and their state (burned or safe). The analysis is based on the comparison between compressive strength, water-cement ratio, slump, porosity and durability. Otherwise, the impact on economy is analyzed, a priori, by studying the effect of reducing the price of the resulting concrete on construction spending. The resulted recommendations indicate the sizes of aggregates which may constitute the best composition for recycling and processing concrete, and the best use for each type of concrete depending on behavior and economy effect.

Revista ingeniería de construcción, 2015

This article addresses the preparation of a concrete using recycled aggregates obtained from the rubble recovery of concrete and masonry works. The study shows some aspects such as: compressive strength at 3, 7, 14, 28, 56 and 91 days; porosity, ultrasonic pulse speed and carbonation; economic costs compared to a conventional concrete; and a review of the public policies on sustainable construction and the use of rubble, in the city of Medellin, Colombia. For some mixes, the compressive strength and the ultrasonic pulse speed measurements were approximately the 98% of that of the reference mix. Likewise, the mix prepared with 100% of recycled aggregates showed a difference in the carbonation deepness of only 0.7 mm compared with the mix of reference for a simulated age of 27 years. The results obtained with the replacement of natural coarse and fine aggregates in 25%, 50%, and 100%, and the advance in the political-administrative guidelines of the city in the last eleven years, allow deducing the possibility of preparing structural and non-structural concretes for massive use in the construction area.

Journal of Sustainable Cement-Based Materials, 2013

The construction industry is one of the most demanding in terms of natural resources, and of the most polluting in terms of emissions to the atmosphere. Concrete is one of the most used materials in engineering and is a paradigm of the consumption of rocks for aggregates, used in polluting industries such as cement production. In trying to reduce the consumption of natural resources, efforts are being made to use waste as recycled aggregates. This fact has evident economic and environmental advantages, but it has a drawback. The concrete prepared with recycled aggregates has lower mechanical strength than ordinary concrete. This decrease of resistance is mainly due to a higher porosity exhibited by the materials from recycled aggregates. But the increase of porosity can be a great advantage in terms of sound absorption. In this work several types of recycled aggregates have been tested, paying special attention to their acoustic behaviour and pore structure. The results show that concrete made with recycled waste are effective in absorbing sound. It might become an alternative to traditional concrete, since recycling samples behave similarly or better in terms of sound absorption, using recycled materials, and increasing their life-cycle. The measurement of acoustic properties, as well as density, has already been undertaken in previous works. This work presents an image analysis methodology that is completely novel, and that helps to understand the acoustic behaviour of concrete elements.

Cement and Concrete Composites, 2007

The majority of worldwide structures use concrete as its main material. This happens because concrete is economically feasible, due to its undemanding production technology and ease of use. However, it is widely recognized that concrete production has a strong environmental impact in the planet. Natural aggregates use is one of the most important problems of concrete production nowadays, since they are obtained from limited, and in some countries scarce, resources. In Portugal, although there are enough stone quarries to cover coarse aggregates needs for several more years, supplies of fine aggregates are becoming scarcer, especially in the northern part of the country. On the other hand, as concrete structures' life cycle comes to an end, an urgent need emerges to establish technically and economically viable solutions for demolition debris, other than for use as road base and quarry fill. This paper presents a partial life cycle assessment (LCA) of concrete made with fine recycled concrete aggregates performed with EcoConcrete tool. EcoConcrete is a tailor-made, interactive, learning and communications tool promoted by the Joint Project Group (JPG) on the LCA of concrete, to qualify and quantify the overall environment impact of concrete products. It consists of an interactive Excel-spreadsheet in which several environmental inputs (material quantities, distances from origin to production site, production processes) and outputs (material, energy, emissions to air, water, soil or waste) are collected in a life cycle inventory, and are then processed to determine the environmental impact (assessment) of the analysed concrete, in terms of ozone layer depletion, smog or "greenhouse" effect.

Revista ALCONPAT, 2015

The opinions expressed by the authors do not necessarily reflect the stance of the editor. The total or partial reproduction of the contents and images of this publication without the prior authorization of ALCONPAT International A.C. is prohibited. RESUMO A geração de resíduos sólidos de concreto, considerados como entulho, está se tornando um problema ambiental. Este material de construção é composto principalmente por cimento Portland (CP), mas um dos problemas é a sua alta temperatura de fabricação, que gera poluentes. O uso de agregados triturados originados da demolição do concreto é aproveitável para a elaboração de Concreto Reciclado, um material que pode diminuir custos, diminuir a contaminação e tornar a edificação mais econômica. Porém, a elaboração de concreto reciclado enfrenta a busca por traços otimizados para se alcançar um maior desempenho mecânico sob solicitações estáticas e dinâmicas. Este artigo faz uma revisão dos avanços internacionais sobre este assunto.

Procedia Engineering, 2017

The issue of using construction rubble was recognized in Europe not earlier than in the nineties of the twentieth century. This was due to economic and ecological considerations. However, recycled aggregate is characterized by high volatility of physical and mechanical properties. The quantity and type of various kinds of impurities harmful to the durability of concrete is virtually unpredictable. For over twenty years various organizations in different countries have tried to sort out this problem and possibly unequivocally define the criteria for the suitability of different types of recycled aggregates to the production of concrete. The article presents and compares the most important guidelines, currently in force, regulating the scope of use of recycled aggregates (RILEM as well as Japanese, German and European standards). The article also contains the results and the analysis of comparative studies of selected physical and mechanical characteristics of concrete produced with the use of natural aggregate and concrete produced with the use of recycled aggregate obtained from milling of masonry.

Cement and Concrete Research, 2004

Fine and coarse recycled aggregates recovered from demolished masonry and concrete structures were utilized in the manufacture of new concrete mixtures. Three properties of these new concretes were analyzed: water absorption, total pores volume, and carbonation. The recycled concrete families were created by replacing parts of the natural aggregates forming families of concrete with 0%, 20%, 50%, and 100% of aggregates from recycled sources. The usual comparison between mixtures by comparison between behaviors of concrete families. This research shows that the mix design nomogram (MDN) is a new and useful tool that allows the researchers to compare properties and behaviors of different concretes. The results show that the family concrete with the highest pore volume and with the same compressive strength of 20, 30, and 40 MPa (2900, 4350, and 5800 psi) did not always correspond to the concrete family with the highest degree of carbonation. This experiment also showed that some compositional characteristics of concrete could have more influence on the durability that the traditional physical aspects.