Use of waste marble aggregates in concrete sciencedirect. Most studies consulted found that water retentivity of fresh mortar made with recycled aggregates was lower. Properties of concrete with plastic waste as aggregate. The fra used come from demolished concrete of known properties. Crushed concrete aggregates also called as recycled concrete aggregates are fragments and pieces of concrete buildings which are demolished or rebuild. Afterwards, the experimental campaign was planned and carried out. Use of recycled concrete aggregates in high strength concretematerials and structures,vol33,november2000, pp. Strength and durability evaluation of recycled aggregate. The mix proportions of the four concretes were designed in order to achieve the same compressive strengths. Construction materials are increasingly judged by their ecological characteristics. Assessment is based on local lci data and on typical conditions in serbia. Concrete is lower than that of virgin aggregate concrete due to the occurrence of porous residual mortar coating the recycled aggregates.
Because concrete is the most widely used construction material in the world today 4, this thesis focuses on a specific component that accounts for 80% of the volume of concrete 5, that is, aggregates. International journal of engineering trends and technology. Recycled aggregates construction aggregate recycling. Therefore, it becomes necessary to recycle the crushed concrete and use it as course aggregate in new concrete mixes. Four different recycled aggregate concretes were produced. Similarly the properties of recycled aggregate concrete are also determined. Recycled concrete aggregate rca produced from demolished pavements in three geographically dispersed locations in washington state were used to perform testson aggregate characte ristics, fresh. Recycled aggregates in concrete aggregate research. The present paper refers to the concrete recycling subject and, more specifically, to a proposal for greek specifications of recycled concrete aggregates rca with reference to international.
In this paper, some characteristics of recycled coarse aggregates obtained by crushing waste readymix concrete, as well. Recycled aggregates produced from all but the poorest quality original concrete can be expected to pass the same tests required of conventional aggregates. Groups were designed to study the effect of recycled coarse aggregates quality content, cement dos age, use of superplasticizer and silica fume. For better control of recycled aggregates grading curve it is recommended that the recycling of cement concrete to be carried out in two stages of crushing.
Aggregates for this study were obtained from crushed concrete cubes. The major constituents of which is natural aggregate such as gravel, sand, alternatively, artificial aggregates such manufactured. Founded in 1904 and headquartered in farmington hills, michigan, usa, the american concrete institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensusbased standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design. This study evaluated the use of recycled concrete as coarse aggregate in new concrete pavements. Many structures that were constructed in india during the construction boom of the 1970s are now required of either major repairs or possible replacement. Proceedings of the nationalsymposium on the use of recycled materials in engineering construction. Recycled concretes made with waste readymix concrete as coarse aggregate. This paper focuses on coarse rca which is the coarse aggregate from the original concrete that is created after the mortar is separated from the rock. Recycled aggregate in concrete civil engineering community. Using fine recycled concrete aggregate for mortar production. In normalstrength concrete, failure in compression almost exclusively involves debonding of the cement paste from the. Transportation applications of recycled concrete aggregate. In fact, characterization results show that the obtained values of flakiness index and sand equivalent of recycled aggregates are consistent with the european standard.
The durable behaviour of recycled concretes is as good as that of conventional one. All the aggregates were immersed in water up to 24 hours and surface dried before use to compensate the effect of initial higher water absorption of recycled aggregates. Recycled concrete with variable content of recycled fine aggregate. Construction aggregate, or simply aggregate, is a broad category of coarse to mediumgrained particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. The effect of using recycled aggregates concrete rca on the basic properties of normal concrete is studied.
The natural and recycled aggregates were characterized. Effect of recycled aggregates on mechanical properties of concrete. Aggregates for concrete bination of gravels or crushed stone with particles predominantly larger than 5 mm 0. Evaluation of recycled concrete for use as aggregate in new. By collecting the used concrete and breaking it up, recycled concrete aggregate rca is created fig. This paper deals with the possibility of using fresh concrete waste as recycled aggregates in concrete. Therefore the concrete wastes had to be separated from the other debris. Respect to the use of natural crushed sand in concrete production, the cirsoc 201. Crushed concrete aggregate cca is granular material manufactured reactivo biuret pdf by removing, crushing, and processing old concrete for reuse as an aggregate source in. Highstrength structural concrete with recycled aggregates.
I would like to express my gratitude to all those who gave me the possibility to complete this project. Some indot contracts specify type ap aggregates for use in ongrade application of portland cement concrete. Aggregates are the major component of any concrete it constitutes about 7080% of the volume of concrete following are the reasons why aggregates are used in concrete 1 they are easily available and they are economical as compared to cement 2 ag. Since they are made of porous materials ceramic materials. Aggregates are inert granular materials such as sand, gravel, or crushed stone that, along with water and portland cement, are an essential ingredient in. Highlights recycled fine aggregate obtained from crushed waste concrete. Concrete manufacture with ungraded recycled aggregates. This paper seeks to provide a solution to the construction industry for using recycled concrete aggregates rca in.
Recycled concrete aggregates contain not only the original aggregates, but also hydrated cement paste. Concrete recycling gains importance because it protects natural resources and eliminates the need for disposal by using the readily available concrete as an aggregate source for new concrete or pavement subbase layers. The spanish code and the american code aci 318, 2008 indicates maximum wc ratios 0. Use of plastic aggregates in concrete international journal of. Use of recycled aggregate in concrete can be useful for. The use of recycled aggregates in concrete prove to be a valuable building materials in technical, environment and economical respect. In this paper, some characteristics of recycled coarse aggregates obtained by crushing waste readymix concrete, as well as the mechanical and durability properties of recycled concretes made by using 25, 50, and 75% of these aggregates, are presented. Bs en 12620 is the predominant specification concerning the use of aggregates for concrete supported by uk national guidance document. Concrete mix designs with 25%, 50%, 75% and 100% of aggregates substitution were formulated. Recycled construction and demolition concrete waste as aggregate. Marine aggregates in concrete mineral products association.
These crushed concrete are cleaned from dirt and broken to smaller pieces to manufacture aggregate which is termed as recycled aggregate. Highstrength concrete containing basalt and normal strength concrete containing limestone yield higher fracture energies with higher coarse aggregate content than with lower coarse aggregate contents. The strength performance of modified concrete specimens was compared with the conventional concrete. Ungraded construction demolition waste and ungraded ground glass were used as aggregate replacements.
Replacement of recycled coarse aggregates with natural coarse. The collected data will also be an essential reference for practicing engineers who face problems concerning the use of these materials in. Use of industrial, construction and demolition waste will be helpful to graduate students, researchers and concrete technologists. Recycled concretes made with waste readymix concrete as. Recycled concrete can be batched, mixed, transported, placed and compacted in the same manner as conventional concrete. Effect of recycled aggregates on mechanical properties of.
Aggregates produced from recycled concrete supply roughly 5 percent of the total aggregates market more than 2 billion t per year, the rest being supplied by aggregates from natural sources such as crushed stone, sand, and gravel. With regard to concrete, compressive strength is widely used as a. In the world of construction, concrete like other materials is playing an important role in development. Results of this specific case study show that impacts of aggregate and cement production phases are slightly larger for rac than for nac but the total environmental impacts depend on the natural and recycled aggregates transport distances and on transport types.
In this paper, the permeability properties of fine recycled aggregate concrete are presented. Berendrecht lock in belgium 19871988 c 35 recycled concrete. Recycled aggregatesprofitable resource conservation. Recycled aggregates main construction aggregate concrete. Evaluation of recycled concrete for use as aggregate in. Moreover, fine aggregate usually consists of natural sand with particles around 4. Concrete and the role of the aggregate regarding concrete, which is the construction material of our era, the protection of the environment concerns three basic axes. Use of recycled aggregates in concrete a paradigm shift. The extensive research on recycled concrete aggregate and recycled aggregate concrete rac as started from year 1945 in various part of the world after second world war, but in a fragmented manner. It indicates that the sand is fine and may improve workability of concrete at the expense of the strength. Pdf the use of recycled aggregates in concrete opens a whole new range of possibilities in the reuse of materials in the building industry.
That means that aggregates have to be transported from longer distances into the. Properties of concrete incorporating recycled concrete aggregates. Condominium complex in hamburg, germany, built 50 years ago. Using fine recycled concrete aggregate for mortar production situation occurred in the silva, bavaresco6 et al. Concrete made with recycled aggregates has a compressive. The compressive strengths of recycled and conventional concretes are similar. The concrete standard bs 8500 has improved the potential for use of recycled aggregates in concrete as has bs en 12620, aggregates for concrete. Strength of concrete incorporating aggregates recycled. For better control of recycled aggregates grading curve it is recommended that the recycling of cement. Recycled aggregates are obtained by compressionimpact crushing of broken cement concrete won, 1999 using equipment such as those presented in fig.
Mixes with 10%, 30%, 50% and 100% by volume replacement of fine natural aggregates fna with fra were produced and tested for water. Recycled aggregates are the materials for the future. Aggregates are becoming increasingly scarce in urban areas. This situation has led to the search for new applications for these wastes, and their use as aggregates in concrete is an interesting alternative. This paste reduces the specific gravity and increases the porosity compared to similar virgin aggregates. Replacement of recycled coarse aggregates with natural. Mar 29, 20 this paper discusses the properties of rca, the effects of rca use on concrete material properties, and the large scale impact of rca on structural members. University, recycled concrete aggregates rca can reduce costs, environmental impacts, and project delivery time when used in concrete pavements garber, et. The use of recycled concrete pavement eliminates the development of waste stockpiles of concrete. Aggregates are used in the making of concrete concrete is composed of water, cement paste, coarse aggregates, fine aggregates, and admixtures aggregates help the strength of the concrete by filling in void spaces and resisting compressive stress. The main subjects of this paper are the grades of the recycled rubble aggregates and the rules to be followed in order to obtain satisfactory performances from recycled aggregate concrete rac.
Pdf recycled aggregate concrete as structural material. The concrete having compressive strength of 20nmm2 m 20 is used and percentages of rubber aggregates are 0, 5, 10, and 15% of normal aggregates. The application of recycled aggregate has been started in. Higher porosity of rca leads to a higher absorption. The aggregates are categorized by size as coarse and fine aggregate. Use of recycled fine aggregate in concretes with durable. First effort has been made by nixon in 1977 who complied all the work on recycled aggregate carried out between 19451977 and prepared a stateof. Includes gravel, crushed stone, sand, slag, recycled concrete and geosynthetic aggregates. The fine and coarse aggregates generally use 60% to 75% of the concrete volume 70% to 85% by mass and will influence the concretes freshly mixed and hardened properties, mixture proportions, and economy. Influence of aggregate characteristics on concrete. Some natural aggregate deposits, called pitrun gravel, consist of gravel and sand that can be readily used in concrete after minimal processing. Mechanical properties of recycled aggregates concrete.
The characteristic of recycled aggregates could be different by its parent concrete because the parent concrete was. Concrete containing metallurgical sludge waste is of higher compressive strength after 7 and 28 days, with up to 60% of waste as a sand. Recycling and reuse of building wastes have been found to be an appropriate solution to the problems of dumping hundred of thousands tons of debris accompanied with shortage of natural aggregates. Review article assessment of recycled aggregate concrete parekh d. The use of recycled concrete pavement eliminates the development of. It is expected that there will be an increase in the use of recycled aggregates for concrete in the next few years, but currently it is not widely available. According to the japanese standard for use of recycled aggregate in concrete, the amount of har mful materials of density less than 1200 kgm3 is limited to 2 kgm3, and plastic, clay, humus and other harmful substances of density less than 1950 kgm3 to 10 kgm3. An experimental program based on two variables proportion of fine aggregates replacement and proportion of coarse aggregates replacement was implemented. Groups were designed to study the effect of recycled coarse aggregates qualitycontent, cement dos age, use of superplasticizer and silica fume. Properties of concrete with recycled concrete aggregate. Mix proportioning for recycled aggregate concrete the same volumetric ratios of the control mix was adopted for the recycled aggregate, however, since different grades of the recycled aggregate with different particle sizes were available, the following approach was considered in the current study.
Recycled aggregates main free download as powerpoint presentation. Comparative environmental assessment of natural and recycled. After demolition of old roads and buildings, the removed concrete is often considered worthless and disposed of as demolition waste. Concrete results showed that 25mp and 30mp strength can be reached using recycled aggregate as a coarse material.
The wolfpack brittany bowers, conner watson, david valecillos, brian grace. The proportions of replacement were 0%, 50%, and 100% by mass of aggregates. Different regulations specify a maximum watercement ratio wc in concretes with durable requirements. The natural aggregates are replaced by rubber aggregates on volume basis. Recycled concrete aggregate is considered as the most abundant and used secondary aggregate in concrete production, other types of solid waste are also being used in concrete for specific purposes. The comprehensive information presented in recycled aggregate in concrete. A study of concrete made with fine and coarse aggregates. Also due to new construction for better economic growth, tructures are s.
The performances of the recycled aggregates concrete were measured through tests of density, air content, workability and compressive and tensile strength. Effect of recycled coarse aggregate on concrete properties. Mar 10, 2015 the comprehensive information presented in recycled aggregate in concrete. Wellchosen recycled aggregates as concrete coarse aggregates are efficient in concrete with strength loss up to 20% of those with natural aggregates which mean it is efficient for light and medium loads with different special concrete types 3,5,6. Review article assessment of recycled aggregate concrete. Vijai department of civil engineering, sethu institute of technology, pulloor, kariapatti, india email. The main subjects of this paper are the grades of the recycled rubble aggregates and the rules to be followed in order to obtain satisfactory performances from recycled aggregate concrete. Using more than 35% of fine recycled aggregate causes an obvious weakness in the concrete strength. With regard to concrete, compressive strength is widely used as a measure of suitability as being fit for purpose. Crushed concrete aggregates properties and uses of. It is called recycled aggregate which can be produced by concrete crusher.
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