Recycled Brick Aggregates Research Articles

Development of Eco-Friendly Concrete Mix Using Recycled Aggregates: Structural Performance and Pore Feature Study Using Image Analysis.

The shortage of natural aggregates has compelled the developers to devote their efforts to finding alternative aggregates. On the other hand, demolition waste from old constructions creates huge land acquisition problems and environmental pollution. Both these problems can be solved by recycling waste materials. The current study aims to use recycled brick aggregates (RBA) to develop eco-friendly pervious concrete (PC) and investigate the new concrete’s structural performance and pore structure distributions. Through laboratory testing and image processing techniques, the effects of replacement ratio (0%, 20%, 40%, 60%, 80%, and 100%) and particle size (4.75 mm, 9.5 mm, and 12.5 mm) on both structural performance and pore feature were analyzed. The obtained results showed that the smallest aggregate size (size = 4.75 mm) provides the best strength compared to the large sizes. The image analysis method has shown the average pore sizes of PC mixes made with smaller aggregates (size = 4.75 mm) as 1.8–2 mm, whereas the mixes prepared with an aggregate size of 9.5 mm and 12.5 mm can provide pore sizes of 2.9–3.1 mm and 3.7–4.2 mm, respectively. In summary, the results confirmed that 40–60% of the natural aggregates could be replaced with RBA without influencing both strength and pore features.

Evaluation of mechanical properties and structural behaviour of concrete pavements produced with virgin and recycled aggregates: an experimental and numerical study

ABSTRACT Due to the large-scale use of materials in highways, the sustainability of materials has attracted considerable interest for years. In this respect, significant effort has been spent investigating the use of recycled aggregates in concrete pavements. This study has been carried out to fill the gap in the structural performance of recycled aggregate concrete pavements. First, properties of concrete mixtures, produced with virgin, recycled concrete and recycled brick aggregates were experimentally measured, and the results were compared. Then, finite element analyses were done by following a novel methodology that considers the well-known previous works. Results showed that replacement of coarse aggregates with recycled aggregates decreases the mechanical properties in various amounts. Due to the resulting performances, for the same slab thickness, decreased maximum stress, increased deflection and stress ratio values were found for recycled aggregate mixtures. Additionally, higher thicknesses and material requirements were found for recycled aggregate concrete for a similar life. Despite the decreased performance and increased material requirements, the use of recycled aggregates in pavements can still be a viable alternative for countries with limited natural resources and landfills. Therefore, based on the findings, several important discussions and suggestions were presented for future works.

Geotechnical assessment and large scale direct shear testing on recycled brick aggregates

The current scenario of handling and recycling of construction and demolition (C&D) waste in India is not very promising. The proper management of C&D waste material is necessary to achieve sustainability goals in the field of Civil Engineering. In this research, the utility of recycled brick aggregates (RBA) in geotechnical applications is assessed by performing an extensive experimental program which includes tests like: particle size distribution, specific gravity, water absorption, modified proctor compaction, relative density, aggregate crushing, slake durability index, aggregate impact and Los Angeles abrasion. Shear strength parameters of RBA are evaluated by performing large scale direct shear test (DST). Source of origin of recycled brick aggregates (RBA) for the present study is MNIT campus, Jaipur. The RBA are found to have good compaction and shear strength characteristics as the values of maximum dry density (MDD), optimum moisture content (OMC), cohesion (c’) and angle of shearing resistance (Ф’), evaluated as 2.03 gm/cm3, 11.52 %, 55.82 kPa and 68° respectively. The large scale DST results are also compared with the available literature. The RBA are found to have susceptibility towards crushing failure, thus this study concludes that the RBA may provide good performance as a base/sub-base or backfill material only under the light loading conditions like: - footpath sub-base, light traffic loading road base and sub-base etc. It is recommended that the incorporation of geosynthetic reinforcements or some durable C&D waste aggregates in RBA may enhance its applicability as a sub-base material under heavy traffic pavements.

Optimization of High-Performance-Concrete properties containing fine recycled aggregates using mixture design modeling

This investigation means to predict and modeling the fresh and hardened concrete behavior containing fine aggregates from concrete and brick wastes, for different recycled aggregates substitution rates. To succeed this, the design of experiments DOE method was used. It is observed that slump of recycled concrete is significantly influenced by the content in recycled concrete aggregates (RCA), natural sand (NS) and recycled brick aggregates (RBA), respectively.The compressive strength (CS) reaches a maximum value of 83.48 MPa with factors values of 25% RBA, and 75% RCA. And HPC’s based on RBA sand presented greater values of flexural strength at 7 days than HPC’s based on RCA sand, it was revealed that this is due to the RBA fines pozzolanic reaction and the production of new CSHs, which leads to better cement matrix densification.Under optimal conditions, themaximum desirability is 0.65, who has given HPC no added natural sand, by mixing recycled sands RBA (9.5%) with RCA (90.5%).The statistical terms result show that the expected models are very well correlated with the experimental data and have shown good accuracy.

Developing SonReb models to predict the compressive strength of concrete using different percentage of recycled brick aggregate

This study was conducted to determine the relationship between nondestructive and destructive tests in concrete cubes using different ratios of normal stone and recycled brick as coarse aggregates. Variations in the grade of concrete, density, and age were considered to make the model prediction more efficient in places where the use of recycled brick aggregates is common. Normal concrete grades M20, M25, and M30 were considered having density variation by replacing stone with recycled brick aggregate, and age by testing concrete strength at 7, 28, and 84 days. A regression model was created using artificial neural networks and multiple regression analyses. The study showed that the regression model developed using an artificial neural network predicted better results. The models obtained from the experiment were compared with other models provided by different authors. The study also considered the effect of using recycled brick aggregate in nondestructive tests and the modulus of concrete.

Modelling the Thermal Energy Storage of Cementitious Mortars Made with PCM-Recycled Brick Aggregates.

This paper reports a numerical approach for modelling the thermal behavior and heat accumulation/liberation of sustainable cementitious composites made with Recycled Brick Aggregates (RBAs) employed as carriers for Phase-Change Materials (PCMs). In the framework of the further development of the fixed grid modelling method, classically employed for solving the well-known Stefan problem, an enthalpy-based approach and an apparent calorific capacity method have been proposed and validated. More specifically, the results of an experimental program, following an advanced incorporation and immobilization technique, developed at the Institut für Werkstoffe im Bauwesen for investigating the thermal responses of various combinations of PCM-RBAs, have been considered as the benchmark to calibrate/validate the numerical results. Promising numerical results have been obtained, and temperature simulations showed good agreement with the experimental data of the analyzed mixtures.

Behaviour of Self Compacting Concrete Columns with Recycled Brick Aggregates

Recycled brick aggregates are preferable alternatives to natural aggregates for minimizing exploitation of natural resources. In this investigation, experimental and analytical works are performed to investigate the behaviour of SCC columns constructed using partial replacement of natural aggregates by RBA and reinforced with steel fibres. The parameters considered for this study is proportion of RBA in SCC mixture and the amount of fibres used. The results of this study reveal that the use of RBA in the place of natural aggregates slightly reduces the strength properties, but this reduction compensated by adding mineral admixtures and steel fibres. The analytical results agreed with the experimental results for SCC columns behaviour.

Thermal energy storage characterization of cementitious composites made with recycled brick aggregates containing PCM

This paper reports the results of an experimental program on sustainable cementitious composites made with Recycled Brick Aggregates (RBAs) employed as carriers for Phase-Change Materials (PCMs). The PCM-RBAs were produced by following an advanced incorporation and immobilization technique, developed and patented at the Institut für Werkstoffe im Bauwesen – TU Darmstadt. Spherical mortar samples made of plain cement paste plus porous RBAs, filled with liquid paraffinic wax, were used for monitoring the thermal behavior of various combinations of PCM-RBAs. The experimental campaign also comprised mechanical tests aimed at observing the effect of PCM in the RBAs, on the resulting mortar strengths under both compression and bending. Promising results have been obtained for the RBA mortars, showing a high thermal energy storage capacity at an almost negligible and acceptable strength loss due to PCM addition.

Shrinkage and creep in structural concrete with recycled brick aggregates

In structural applications, long-term deformations of concrete are particularly important. The aim of this study is to analyze the deformations produced by shrinkage and creep in concretes in which both the fine and coarse fractions have been replaced with recycled brick aggregates (RBA), and to assess their use in structural applications. The percentages of substitution of the natural aggregates by RBA were 20, 35, 50, 70 and 100%. The deformations were measured over 400 days. The results show a strong increase in the shrinkage values and slight variations in the creep, although with substitutions of RBA of up to 20%, the long-term deformations do not exceed the usual values.

Experimental investigation on flexural behavior of hybrid fibers reinforced recycled brick aggregates concrete

This paper aims to investigate the flexural strength, deformation and toughness of steel-polyolefin hybrid fibers reinforced recycled brick aggregates concrete (HFRBAC) through the testing of the beam specimens with the size of 150 × 150 × 550 mm. The test parameters were water/cement ratios (0.28, 0.33, 0.38, 0.43), recycled brick coarse aggregates (RBA) replacement ratios (0%, 25%, 50%, 100%), fiber volume fractions (0%, 0.5%, 1%, 1.5%) and fiber types. The experimental results showed that steel-polyolefin hybrid fibers lead to significant improvement of the compressive strength and flexural behavior of HFRBAC, due to the synergistic interaction of fibers with RBA and natural coarse aggregates (NA). The average compressive strengths of HFRBAC with different testing parameter range from 34.69 MPa to 51.62 MPa. It was observed that the load-axial deformation curves of HFRBAC beams shows the similar tendency with the relevant load–deflection curves. The addition of steel-polyolefin hybrid fibers significantly enhances the post-cracking behavior of recycled brick aggregates concrete (RBAC), especially the flexural toughness at the first-peak point, L/600 point and L/150 point. Under the same fiber volume fraction, the effects of steel-polyolefin hybrid fibers on compressive strength and flexural behavior of HFRBAC are weaker than that of steel fiber, but better than that of polyolefin fiber.

RETRACTED: Paul et al. Properties of Normal and Recycled Brick Aggregates for Production of Medium Range (25–30 MPa) Structural Strength Concrete. Buildings 2018, 8, 72

As the authors of the title paper [1], it is with great regret that we inform the readership of Buildings that we have asked the journal’s publisher, MDPI, to retract the paper from the scientific literature[...]

RETRACTED: Properties of Normal and Recycled Brick Aggregates for Production of Medium Range (25–30 MPa) Structural Strength Concrete

This study compares the properties of normal and recycled brick aggregates to produce a medium range (25–30 MPa) compressive strength of structural grade concrete. Up to date, brick aggregates are commonly used in structural concrete in some South Asian and African countries. Many concrete structures which were built in the last century are made from brick aggregates and some of them are already in a position of ending of their service life. At the same time, population and economic growth is forcing the demolition of many old structures. Therefore, there is a huge flow of construction and demolition waste and thereby it is necessary to recycle the waste to overcome the problem of occupying the landfill sites. For this study, recycled brick aggregates were collected from the various demolished building sites and their physical and mechanical performance were then compared with the concrete made from normal brick aggregates. It is found that the mechanical properties of recycled brick concrete are comparable to that of normal brick aggregate at medium strength level. The production cost of recycled brick concrete is also found to be 10–12% lower than normal brick aggregates.

Influence of recycled brick aggregates on properties of structural concrete for manufacturing precast prestressed beams

The European Union has set as a target for 2020 the reuse of 70% of non-hazardous construction and demolition waste (C&DW) in order to reduce its impact on the environment and on health, as well as to improve the efficiency of available resources.Within the framework of this initiative, this study addresses the use of ceramic aggregates from precast production facilities in order to replace natural aggregates for manufacturing structural concrete for the production of precast prestressed beams. The objective of this study is to evaluate the influence of the substitution of the fine and coarse fraction of natural aggregates for ceramic brick aggregates in the mechanical properties of concrete, with the aim of applying the results obtained to the subsequent manufacture and testing of prestressed beams commonly used in one-way slabs.The focus of this analysis is on the replacement of the fine fraction of the natural aggregate by the recycled one. However, the coarse aggregate was also substituted. Furthermore, two hardly studied replacement percentages (35% and 70%) were included in the experimental program. The main result obtained was that prestressed beams can be manufactured with up to 35% of the proposed type of ceramic recycled aggregates in order to reach the requirements of the European standards.

Behavior of Low Grade Steel Fiber Reinforced Concrete Made with Fresh and Recycled Brick Aggregates

In recent years, recycled aggregates from construction and demolition waste (CDW) have been widely accepted in construction sectors as the replacement of coarse aggregate in order to minimize the excessive use of natural resources. In this paper, an experimental investigation is carried out to observe the influence of low grade steel fiber reinforcements on the stress-strain behavior of concrete made with recycled and fresh brick aggregates. In addition, compressive strength by destructive and nondestructive tests, splitting tensile strength, and Young’s modulus are determined. Hooked end steel wires with 50 mm of length and an aspect ratio of 55.6 are used as fiber reinforcements in a volume fraction of 0% (control case), 0.50%, and 1.00% in concrete mixes. The same gradation of aggregates and water-cement ratio (w/c=0.44) were used to assess the effect of steel fiber in all these concrete mixes. All tests were conducted at 7, 14, and 28 days to perceive the effect of age on different mechanical properties. The experimental results show that around 10%～15% and 40%～60% increase in 28 days compressive strength and tensile strength of steel fiber reinforced concrete, respectively, compared to those of the control case. It is observed that the effect of addition of 1% fiber on the concrete compressive strength is little compared to that of 0.5% steel fiber addition. On the other hand, strain of concrete at failure of steel fiber reinforced concrete has increased almost twice compared to the control case. A simple analytical model is also proposed to generate the ascending portions of the stress-strain curve of concrete. There exists a good correlation between the experimental results and the analytical model. A relatively ductile failure is observed for the concrete made with low grade steel fibers.

Experimental Study on the Mix Design and Fundamental Properties for Mixd Mortars Using Recycled Fine Aggregates

This paper concerns the use of recycled fine concrete and clay brick aggregates to respectively globally replace natural fine aggregates (sand) in the production of mixed mortar. The fundamental properties such as the compressive strength and the shrinkage ratio of mixed mortar made of the recycled fine aggregates are tested and discussed in detail. The experimental results indicated that it is viable to produce mixed mortar using recycled fine concrete and clay brick aggregates, the compressive strength of mixed mortar made of recycled fine aggregates is lower than that of mixed mortar made of natural fine aggregates and the shrinkage ratio of mixed mortar made of recycled fine aggregates is larger, cured in natural environment.

Behaviour of concrete with low-strength bricks as lightweight coarse aggregate

The quantity of masonry demolition waste is higher than that of concrete waste. A review shows that extensive studies have been made of recycled concrete aggregates with only limited studies on recycled brick aggregate. The objective of this paper is to investigate the use of two types of low-strength bricks as lightweight coarse aggregate in concrete. After characterisation of recycled brick aggregates, a study of the relative influence of different parameters on the strength of concrete follows, adopting a five-factor, eight-run two-level fractional factorial experimental design. While cement content, aggregate condition (pre-wet or dry) and aggregate strength influence concrete strength significantly, the contributions of the maximum size of aggregate and sand percentages are relatively very low. Finally, a systematic behavioural study is undertaken adopting the volumetric method of mix proportioning for structural lightweight aggregate concrete. Typical guidelines for mix proportioning of such lightweight aggregates is presented.

Behaviour of concrete with low-strength bricks as lightweight coarse aggregate

The quantity of masonry demolition waste is higher than that of concrete waste. A review shows that extensive studies have been made of recycled concrete aggregates with only limited studies on recycled brick aggregate. The objective of this paper is to investigate the use of two types of low-strength bricks as lightweight coarse aggregate in concrete. After characterisation of recycled brick aggregates, a study of the relative influence of different parameters on the strength of concrete follows, adopting a five-factor, eight-run two-level fractional factorial experimental design. While cement content, aggregate condition (pre-wet or dry) and aggregate strength influence concrete strength significantly, the contributions of the maximum size of aggregate and sand percentages are relatively very low. Finally, a systematic behavioural study is undertaken adopting the volumetric method of mix proportioning for structural lightweight aggregate concrete. Typical guidelines for mix proportioning of such lightweight aggregates is presented.