Durable Performance of Recycled Concrete Using Coarse and Fine Recycled Concrete Aggregates in Air Environment

2011 ◽  
Vol 261-263 ◽  
pp. 446-449 ◽  
Author(s):  
Ping Hua Zhu ◽  
Xin Jie Wang ◽  
Jin Cai Feng
Keyword(s):  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Structural Concrete ◽  
Aggregate Concrete ◽  
Cube Strength ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Natural Aggregate ◽  
Concrete Mixtures

The influence of synchronous use of coarse and fine recycled concrete aggregates on durable performance of recycled aggregate concrete (RAC) in air environment were determined. In this study, three series of concrete mixtures were prepared, in which the coarse recycled aggregate was used as 0%, 30%, 60% and 90% replacements of coarse natural aggregate and fine recycled aggregate as 0%, 10%, 20%, and 30% replacements of fine natural aggregate. Meanwhile, fly ash and slag were used as 15%, 25%, 35% and 45% replacements of cement, respectively. The carbonation depths, compressive cube strength, workability of RACs were tested. The experimental results showed that RAC with synchronous use of coarse and fine recycled concrete aggregates had satisfactory durable performance. When RAC was used as structural concrete in air environment, the optimum synchronous replacements are 60% for coarse recycled aggregate and 20% for fine recycled aggregate.

Structural Concrete with Recycled Aggregate: Advances in Mechanical Properties, Durability and Sustainability

2016 ◽  
Vol 847 ◽  
pp. 553-558 ◽  
Author(s):  
Marc Antonio Liotta ◽  
Marco Viviani ◽  
Carlotta Rodriquez
Keyword(s):  
Cement Mortar ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mix Design ◽  
Elastic Behavior ◽  
Structural Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Ordinary Concrete

A large number of tests has been carried out in the last 15 years all around the world to study the possibility to use recycled concrete aggregates (RCA) to produce structural concrete.Earlier tests indicated that RCA concrete had lower properties in comparison to ordinary concrete, such as lower elastic modulus, a more brittle post-elastic behavior, lower workability, higher shrinkage and creep.Most of these issues have been addressed to the content of cement mortar remaining in adhesion to the aggregate after the recycling processes and that cannot be totally eliminated without high economic and ecological costs. This cement mortar which has undergone the crushing process creates zones of weakness in the RCA, causes higher water absorption, higher concrete porosity and causes the decay of the aforementioned properties.More recent tests prove that Recycled Concrete shows this peculiar problems only with a percentage of substitution of standard aggregates with RCA higher than 30%. Under this percentage recycled aggregate concrete (RAC) can be considered as a standard concrete, on condition that an appropriate mix design is performed.

The Research of Green High Performance Recycled Construct Materials

2011 ◽  
Vol 71-78 ◽  
pp. 4471-4475
Author(s):  
Xiao Xiong Zha ◽  
Kai Zhang
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Experimental Studies ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Large Water

Recycled concrete aggregates have large porosity, large water absorption and high crush index. Mechanical properties of recycled concrete aggregates could be improved by adding activated water instead of ordinary water. On the basis of the experimental studies, this paper analyzes the influences on recycled concrete compression strength when using activated water. There are many different factors such as the kinds and amounts of alkali and the water slag ratio affecting the compressive strength of recycle geopolymer. The results show that activated water has a high enhancement on compressive strength of recycled aggregate concrete, and the highest compressive strength of recycled geopolymer is 57.3MPa.

scholarly journals Self-cementing properties of recycled concrete aggregates (RCA) on the example of tests of material and layers of pavement subbase

2014 ◽  
Vol 13 (4) ◽  
pp. 101-107
Author(s):  
Jakub Fengier ◽  
Andrzej Pożarycki
Keyword(s):  
Compressive Strength ◽  
Field Tests ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Concrete Materials

The work is an attempt to summarize the experience concerning the diagnosis of the practical properties of recycled aggregate concrete cement (RCA). It describes the phenomenon of self-cementing properties which was investigated in both the laboratory and on field tests including compressive strength of RCA, non-conventional oedometric tests of RCA and plate bearing tests on the surface of RCA layer. The described self-cementing properties were remarked, however, the RCA material was characterized by smaller increase in the value of parameter EV2 in a 2-year period of time than recycled concrete materials described in the available literature.

Recycled Aggregate Concretes for Structural Applications: From Investigation to Design

2012 ◽  
Vol 548 ◽  
pp. 209-214
Author(s):  
Valeria Corinaldesi ◽  
Giacomo Moriconi
Keyword(s):  
Elastic Modulus ◽  
Drying Shrinkage ◽  
Structure Design ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Concrete Mixtures ◽  
Structural Applications

In this paper an investigation of mechanical behaviour and, in particular, elastic properties of recycled aggregate concrete (RAC) is presented. RACs were prepared by using a coarse aggregate made of old concrete particles coming from a recycling plant in which rubble from demolition of reinforced concrete structures is collected and suitably treated. Several concrete mixtures were prepared by using either the only virgin aggregates (as reference) or 30% recycled concrete aggregates replacing gravel, and by using two different kinds of cement. Different water to cement ratios were adopted ranging from 0.40 to 0.60, while concrete workability was always maintained at the same rate by adding different amounts of water-reducing admixture. Concrete compressive strength, elastic modulus and drying shrinkage were evaluated. Results obtained showed that structural concrete up to C32/40 strength class can be manufactured with RAC. Moreover, results obtained were discussed in order to obtain useful information for RAC structure design, particularly in terms of elastic modulus and drying shrinkage prediction.

Influence of Waste Concrete Aggregates on the Performance and Durability of OPC Concrete

2005 ◽  
Vol 2 (2) ◽  
pp. 49
Author(s):  
Ahmad Ruslan Mohd Ridzuan ◽  
Azmi Ibrahim ◽  
Abdul Manaff Mohd Ismail
Keyword(s):  
Compressive Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Moisture Condition ◽  
Aggregate Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Waste Concrete

The effects of using crushed waste concrete as course aggregates upon compressive strength and carbonation were investigated. Waste concrete cubes, which had been tested for compressive strength in compliance with construction specification, were crushed and utilized as coarse recycled aggregates in new concrete. It is important to mention that, in order to simulate the real life conditions, waste concrete with very minimal information about its originality was used in its natural moisture condition. Tests on the aggregates showed that the recycled concrete aggregates have lower specific gravity and bulk density but have higher water absorption capacity than the natural aggregates. The resistance to mechanical actions such as impact and crushing for recycled concrete aggregates is also lower. Concrete mixes with design strength of 30 N/mm2, 35 N/mm2 and 40 N/mm2 were prepared using this recycled aggregates as coarse aggregates and tested. From the strength point of view the recycled aggregate concrete compared well with natural aggregate concrete. Therefore, it could be considered for various potential applications. With respect to resistance to carbonation the recycled aggregate concrete shows comparable performance.

Experimental Research on Thermal Mechanical Behavior of Recycled Aggregate Concrete from Earthquake-Stricken Area

2011 ◽  
Vol 217-218 ◽  
pp. 1081-1085 ◽  
Author(s):  
H.Q. Yan ◽  
Ying Peng ◽  
Qing Yuan Wang
Keyword(s):  
Compressive Strength ◽  
Experimental Research ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Practical Engineering ◽  
Temperature Exposure

Recycled aggregate concrete (RAC) is a kind of practical and economic material to reuse the great amount of construction and demolition wastes, which has received many discussions nowadays. In consistent with sustaining development, the recycled concrete that is made from recycled concrete aggregates could be a perfect solution to resource and environment preservation. Its thermal mechanical properties are different from other concretes as a result of different property of the aggregate of recycled concrete and other concrete. However, little research has been done under high temperatures. Therefore, on the basis of experimental research, the thermal mechanical behaviors and microstructure of recycled concrete are studied in this paper. The present paper deals with investigations on the effect of high temperature exposure on the compressive strength of recycled aggregate concrete cube specimens which are made from different proportion of recycled aggregate such as 0%、50%、100%. Experiments were conducted to study the compressive strength variations with increasing temperatures, up to 700 °C, and the subsequent cooling modes such as natural and spray cooling. Then micro-structural observations of the specimens by means of scanning electron microscopy (SEM) were obtained. Based on the analysis of experiment results, it can be proved that it is feasible to apply recycled concrete to practical engineering.

scholarly journals Effect of Recycled Concrete Aggregates on Compressive Strength and Water Permeability of Concrete

2020 ◽  
Vol 14 ◽  
Keyword(s):  
Compressive Strength ◽  
Negative Impact ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Coarse Aggregates ◽  
Natural Aggregates

This paper discusses the effects of recycled concrete aggregates (RCA) on compressive strength and permeability of recycled aggregate concrete (RAC) by using recycled concrete aggregates as a replacement of natural coarse aggregates (NCA). Four replacement percentages were used to study the effect of replacement. Replacement percentages used were 30%, 50%, 70% and 100% with 0% replacement was used as control. Mix design of 1:1.24:2.6 was used in the study with water to cement ratio of 0.43. Influence of RCA on compressive strength was determined for all the mixes as per ASTM C39 standard. The permeability of all the mixes was determined by measuring absorption, sorptivity and Darcy’s coefficient. Results of compressive strength indicated that concrete with 30% replacement of NCA can be successfully used in structural concrete without compromising too much on strength. Whereas, the replacement of natural aggregates with RCA has a negative impact on the permeability of concrete at all replacement levels. Absorption, sorptivity and permeability of natural aggregate concrete is lower as compared to RAC with 30% replacement showing the better performance as compared to other replacement ratios.

Shear strength of reinforced concrete beams with recycled aggregates

2019 ◽  
Vol 22 (8) ◽  
pp. 1938-1951 ◽  
Author(s):  
George Wardeh ◽  
Elhem Ghorbel
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Strain Softening ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Opening Displacement ◽  
Aggregate Concrete ◽  
Natural Aggregate ◽  
Hinge Model

This article presents an experimental program on the shear behavior of beams without transversal reinforcement manufactured with natural aggregate concrete and 100% recycled aggregate concrete. The beams were tested under four-point bending for a shear span-to-depth ratio ( a/ d) equal to 1.5 and 3.0. The mechanical properties of two mixes were characterized in terms of compressive strength, splitting tensile strength, and elastic modulus. Three-point bending tests were performed on plain pre-notched samples in order to determine the fracture properties by an inverse analysis of experimental force–crack mouth opening displacement curves using the analytical nonlinear hinge model and a power law strain-softening relationship. The strain-softening law is described by two parameters being, respectively, the power n and the critical crack opening displacement wc. The experimental results show that, for the same class of compressive strength, tensile strength, fracture energy, and the shear strength of recycled aggregate concrete are lower than natural aggregate concrete. The decrease in the fracture energy and the shear strength is consistent with the decrease in the splitting tensile strength of the recycled aggregate concrete mixes compared to the natural aggregate concrete. Critical shear crack theory was adopted to model the shear behavior of beams tested with a/ d = 3.0. For an accurate evaluation of the deformation capacity of tested beams, the nonlinear hinge model for recycled concrete members was extended to recycled concrete sections. For deep beams ( a/ d = 1.5), the strut-and-tie model was used. Finally, comparisons of prediction models to a wide range of experimental data are presented.

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