Evaluation of Mechanical Characteristics of Cement Mortar with Fine Recycled Concrete Aggregates (FRCA)

One of the growing demands in concrete manufacture is the availability of natural fine aggregates, which account for 35% to 45% of the total concrete. An alternative method of disposal of fine recycled concrete aggregates (FRCA) generated from demolition and construction waste (C&DW) is their usage in mortar and the development of recycled mortar. The main aim of this research work is to evaluate the viability of incorporating FRCA from urban C&DW for the manufacture of cement-based mortars. Simple processing techniques like washing and sieving are adopted to improve the FRCA quality. Physical and chemical characterization of ingredients is carried out. In total four mixes of 1:3 (cement: sand) mortar with partial replacement of normalized sand with FRCA (0%, 25%, 50%, and 100%) are evaluated for mechanical properties. Water to cement ratio for all four mortar mixes are determined by fixed consistency. Mechanical and physical properties like density, compressive strength, and flexural strength are studied for various curing periods, and the result is that the optimum usage of FRCA is 25% based on a 90-day curing period.

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Utilization of Recycled Concrete Aggregates in Stone Mastic Asphalt Mixtures

Advances in Materials Science and Engineering ◽

10.1155/2014/902307 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 7

Author(s):

Mohammad Saeed Pourtahmasb ◽

Mohamed Rehan Karim

Keyword(s):

Design Method ◽

Recycled Concrete ◽

Engineering Properties ◽

Partial Replacement ◽

Concrete Aggregate ◽

Recycled Concrete Aggregates ◽

Material Recycling ◽

Mastic Asphalt ◽

Fine Aggregates ◽

Stone Mastic Asphalt

Recycled concrete aggregate (RCA) is considered as one of the largest wastes in the entire world which is produced by demolishing concrete structures such as buildings, bridges, and dams. It is the intention of scientists and researchers, as well as people in authority, to explore waste material recycling for environmental and economic advantages. The current paper presents an experimental research on the feasibility of reusing RCA in stone mastic asphalt (SMA) mixtures as a partial replacement of coarse and fine aggregates. The engineering properties of SMA mixtures containing RCA have been evaluated for different percentages of binders based on the Marshall mix design method. The outcomes were statistically analyzed using two-factor analysis of variance (ANOVA). Test results revealed that the performance of SMA mixtures is affected by RCA due to higher porosity and absorption of RCA in comparison with virgin granite aggregates. However, the engineering properties of SMA mixtures containing a particular amount of RCA showed the acceptable trends and could satisfy the standard requirements. Moreover, to achieve desirable performance characteristics, more caution should be made on properties of SMA mixtures containing RCA.

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Slope Stability Analysis of Recycled Concrete Fine Aggregate Stabilized and Blended Soils

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.e2730.039520 ◽

2020 ◽

Vol 9 (5) ◽

pp. 991-994

Keyword(s):

Limit Equilibrium ◽

Recycled Concrete ◽

Engineering Properties ◽

Cement Kiln ◽

Concrete Aggregate ◽

Fine Aggregate ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Fine Aggregates ◽

Kiln Dust

Recycled concrete aggregate (RCA) is one of the major material generated from municipal soild waste industry. In the current study, recycled concrete aggregates are collected from the demolished building. The index and engineering properties of crushed concrete and locally available soil are determined. The study aims at effective reuse of demolition concrete waste as backfill of earth retaining walls. RCA passing through 4.75mm is stabilized by using Cement kiln dust (CKD) and Fly Ash (FA) in various proportions. Red soil is partially replaced by 30%, 50%, and 70% with recycled concrete fine aggregates. A numerical model is developed using limit equilibrium software i.e GeoStudio Slope/w. It is found that 15% CKD and 15% FA is optimum to stabilize the material. In case of blended soils, 30% replacement with RC-FA is found to be optimum

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Properties of Concrete with Partial Replacement of Natural Aggregate by Recycled Concrete Aggregates from Precast Production

Procedia Engineering ◽

10.1016/j.proeng.2016.07.387 ◽

2016 ◽

Vol 151 ◽

pp. 360-367 ◽

Cited By ~ 10

Author(s):

Iveta Nováková ◽

Karel Mikulica

Keyword(s):

Recycled Concrete ◽

Partial Replacement ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Natural Aggregate

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Rheology of Alkali-Activated Mortars: Influence of Particle Size and Nature of Aggregates

Minerals ◽

10.3390/min10080726 ◽

2020 ◽

Vol 10 (8) ◽

pp. 726

Author(s):

Sara Gismera ◽

María del Mar Alonso ◽

Marta Palacios ◽

Francisca Puertas

Keyword(s):

Particle Size ◽

Aggregate Size ◽

Recycled Concrete ◽

Partial Replacement ◽

Rheological Parameters ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

General Terms ◽

Dynamic Yield ◽

Alkali Activated

The effect of two precursors (slag and fly ash), different particle size distribution, and three types of aggregate (siliceous sand, limestone, and recycled concrete) on alkali-activated material (AAM) mortar rheology were studied and compared to their effect on an ordinary Portland Cement (OPC) mortar reference. Stress growth and flow curve tests were conducted to determine plastic viscosity and static and dynamic yield stress of the AAM and OPC mortars. In both OPC and AAM mortars, a reduction of the aggregate size induces a rise of the liquid demand to preserve the plastic consistency of the mortar. In general terms, an increase of the particle size of the siliceous aggregates leads to a decrease of the measured rheological parameters. The AAM mortars require higher liquid/solid ratios than OPC mortars to attain plastic consistency. AAM mortars proved to be more sensitive than OPC mortars to changes in aggregate nature. The partial replacement of the siliceous aggregates with up to 20% of recycled concrete aggregates induced no change in mixing liquid uptake, in either AAM or OPC mortars. All the AAM and OPC mortars studied fitted to the Bingham model.

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Interlocking Pavement Tiles using RCA with Industrial Waste as Admixtures

Proceedings of International Web Conference in Civil Engineering for a Sustainable Planet ◽

10.21467/proceedings.112.52 ◽

2021 ◽

Author(s):

Anjana S ◽

Diya Elizabeth Isaac ◽

Neelanjana S ◽

Aswathy G

Keyword(s):

Fly Ash ◽

Industrial Waste ◽

Recycled Concrete ◽

Partial Replacement ◽

Normal Concrete ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Coarse Aggregates ◽

Loss Of Strength ◽

Enormous Quantity

The unprecedented increase in construction and developmental activities in the current era brings with it many irreversible impacts on the environment. The major impacts being the depletion of natural resources and generation of an enormous quantity of Construction and Demolition (C&D) wastes. Hence it has become important to reuse and recycle C & D wastes generated. These wastes can be processed to obtain Recycled Concrete Aggregates (RCA), which can be used for producing recycled concrete. It was found that the strength of Recycled concrete matches with that of paver quality concrete. Therefore, the study aims at producing interlocking paver blocks by replacing the normal coarse aggregates in pavers by RCA along with fly ash as admixture, an industrial waste. Fly ash being a pozzolanic admixture is used in order to overcome the loss of strength due to the addition of RCA. In the present study, a 30% replacement of normal aggregates with RCA and 15% replacement of cement with fly ash in the mix was used as it was found to provide the optimum strength. A comparison of the important properties of paver blocks were conducted between normal concrete pavers, pavers with RCA replacement and pavers with RCA replacement and fly ash. It was found out from the study that Interlocking pavers with partial replacement of normal aggregates with RCA and fly ash obtained strength comparable to that of normal paver blocks. Hence these paver blocks can be used for laying of roads and can contribute towards a sustainable development.

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Rheological and Mechanical Properties of Ultra-High-Performance Concrete Containing Fine Recycled Concrete Aggregates

Materials ◽

10.3390/ma12223717 ◽

2019 ◽

Vol 12 (22) ◽

pp. 3717 ◽

Cited By ~ 3

Author(s):

Lanzhen Yu ◽

Lili Huang ◽

Hui Ding

Keyword(s):

Mechanical Properties ◽

High Performance ◽

High Performance Concrete ◽

Deformation Behaviour ◽

Recycled Concrete ◽

Ultra High Performance Concrete ◽

Replacement Rate ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Fine Aggregates

The manufacturing process of ultra-high-performance concrete (UHPC) leads to a considerable amount of greenhouse gas emissions, which contribute to global warming. Using recycled concrete aggregates (RCA) to replace natural sand helps to reduce natural resources and energy consumption. In this study, the feasibility of manufacturing UHPC with fine RCA was investigated for the sustainable development of construction materials industry. We aimed to study the rheological properties, autogenous shrinkage, mechanical properties, and pore structure of UHPC with different amounts of RCA. The natural aggregate content was replaced with fine RCA at rates of 0, 20, 40, 60, 80, and 100 wt.%, and the packing density of the mixed fine aggregates in this study was estimated using a linear packing model. It was found that (1) the workability, mechanical properties, and deformation behaviour of UHPC with fine RCA were comparable to or even higher than those of UHPC made of high-quality aggregates; (2) the optimal replacement rate of fine RCA was in the range of 40–60 wt.%, considering the mechanical properties and deformation behaviour of UHPC; (3) the tensile strength, flexural strength, and Young’s modulus of UHPC increased by 6.18%, 12.82%, and 3.40%, respectively, when the replacement rate of fine RCA was 60 wt.%; (4) the maximum packing density of mixed fine aggregates presented a monotonic decreasing trend as the replacement percentage of fine RCA increased. These findings help to encourage and further promote the utilisation of RCA to produce UHPC.

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Punching Behavior Of Self-Compacting Concrete Slabs Incorporating Coarse Recycled Concrete Aggregates

Wasit Journal of Engineering Sciences ◽

10.31185/ejuow.vol8.iss1.147 ◽

2020 ◽

Vol 8 (1) ◽

pp. 1-11

Author(s):

Malik K. E. Altaee ◽

Jamal A. S. Khudair

Keyword(s):

Reinforced Concrete ◽

Recycled Concrete ◽

Reduction Ratio ◽

Partial Replacement ◽

Concrete Slabs ◽

Hardened Concrete ◽

Self Compacting Concrete ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Maximum Reduction

This paper presents an experimental investigation on the effects of incorporating coarse recycled concrete aggregates (RCA) on the punching and flexural behaviour of reinforced concrete two-way slabs. For this purpose, four concrete mixes were designed with various substitution ratios of natural coarse aggregates (NCA) by RCA 0% (reference mix), 25, 50 and 75%. Subsequently, fourteen 800 × 800 mm × variable thickness reinforced concrete slabs (two per concrete type) were cast and subjected to punching and flexural tests. Different parameters that affect the behavior of two-way slabs were studied including type of failure, replacement ratios of NCA by RCA, amount of main reinforcement, thickness and loading patch size. In order to investigate the effect of RCA incorporation on hardened concrete properties (compressive strength Fcu, tensile Ft strength, flexural Fr strength and modulus of elasticity Ec), different replacement ratios were considered, while the quantity of cement was kept equaled for all the mixes (with and without RCA). Hardened concrete samples results showed that Fcu, Ft, Fr and Ec were decreased by (8.62, 13.54 and 19.12%), (13.08, 17.63 and 25.46%), (10.02, 21.67%, and 34.30%) and (9.69, 15.65 and 16.62%) respectively, for the (25, 50 and 75%) replacement ratios compared with samples made from SCC without RCA. The experimental results of slabs showed that the cracking and ultimate load (11% maximum reduction ratio) and moment (19.5% maximum reduction ratio) capacities of slabs were decreased compared with slabs made from SCC without RCA. Moreover, the load deflection curves were almost identical with proportional increase to the RCA content. From the general behavior, ultimate capacity, deflections, failure angle and crack pattern results, it can be concluded that the recycled concrete aggregate can be used as a partial replacement of natural coarse aggregate to produce self-compacting concrete mixes, where the behavior of two-way slabs cast with SCC containing RCA can considered acceptable.

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Impact of Long-Term Loading on Reinforced Concrete Beams Made with Partial Replacement of Coarse Aggregates with Recycled Aggregates from Old Concrete

Engineering, Technology & Applied Science Research ◽

10.48084/etasr.2498 ◽

2019 ◽

Vol 9 (1) ◽

pp. 3818-3821 ◽

Cited By ~ 1

Author(s):

M. Oad ◽

A. H. Buller ◽

B. A. Memon ◽

N. A. Memon

Keyword(s):

Reinforced Concrete ◽

Concrete Beams ◽

Recycled Concrete ◽

Reinforced Concrete Beams ◽

Partial Replacement ◽

Short Term ◽

Concrete Aggregates ◽

Recycled Concrete Aggregates ◽

Coarse Aggregates ◽

Sustained Loading

This research work presents an experimental evaluation of the effect of sustained loading on reinforced concrete beams made with 50% replacement of natural coarse aggregates with aggregates from old concrete. A total of 9 RC beams were cast, 6 with natural coarse aggregates and 3 with recycled concrete aggregates. All beams were cured for 28 days in standard fashion. Among the first batch, 3 beams were used to test under short term loading till failure. An application of 50% of short-term loading followed on all beams assembled on purpose made frames. All beams were monitored for deflection, strain, and cracking. Both deflection and strain remained within limits. Crack monitoring revealed maximum crack width 0.5 mm. After six months of sustained load, beams were removed from the frames and tested in universal load testing machine with central point load till failure. The load-deflection pattern of all beams was observed to be almost similar and 22.12% higher in recycled concrete beams than all-natural aggregate beams. The results show promising use of recycled concrete aggregates in new concrete subjected to sustained loading.

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