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

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

scholarly journals Utilization of Recycled Concrete Aggregates in Stone Mastic Asphalt Mixtures

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
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.

scholarly journals Effect of Steel Fibers on the Performance of Concrete Made with Recycled Concrete Aggregates and Dune Sand

2020 ◽  
Vol 9 (1) ◽  
pp. 2188-2193
Keyword(s):  
Coarse Aggregate ◽  
Preliminary Test ◽  
Recycled Concrete ◽  
Steel Fibers ◽  
Concrete Aggregate ◽  
Fine Aggregate ◽  
Dune Sand ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Acid Test

This paper aims to develop and evaluate the performance of concrete made with recycled concrete aggregates (RCA) and dune sand (DS) in addition with steel fibers (SF). This work is mainly intended to find the effective ways to reutilize the recycled concrete aggregates as coarse aggregate and due to sand demand dune sand were used as a fine aggregate. Different mechanical and durability properties of recycled concrete aggregates (RCA) and dune sand (DS) concrete mixtures were evaluated. To ensure the properties of cement, fine aggregate, coarse aggregate, recycled concrete aggregate and dune sand preliminary test were determined. Mix design is formulated based on its properties and requirements. Experimentation has been done by using M25 grade concrete. Ordinary Portland cement is used. Fine aggregate and coarse aggregate were partially replaced by recycled concrete aggregates and dune sand at different proportions (25%, 50%, 75%) in addition with 0.25% of steel fibers. Various strengths such as tensile strength, compressive strength, flexure strength and modulus of elasticity are determined. In particular for cube different tests such as non-destructive test (NDT), sorptivity, permeability and acid test has been done. It has been observed that the M2 mix (50% of recycled concrete aggregates and dune sand) has produced better results comparatively.

scholarly journals Settlement Analysis of Recycled Concrete Fine Aggregate Blended Soils using Geostudio

2019 ◽  
Vol 9 (2) ◽  
pp. 3007-3010
Keyword(s):  
Recycled Concrete ◽  
Engineering Properties ◽  
Real Field ◽  
Fine Aggregate ◽  
Virgin Soil ◽  
Concrete Aggregates ◽  
Finite Element Software ◽  
Crushed Concrete ◽  
Fine Aggregates ◽  
Settlement Analysis

Crushed concrete (CC) is one of the most abundant waste materials generated from construction industry. This material is widely recycled and used in various applications like pavement, concrete aggregates and backfilling. Crushed concrete is mixed with any of virgin soil to increase the engineering properties of soil. In the present study, a sample of crushed concrete is collected from demolished buildings at Secunderabad and the material is segregated according to gradation for the present study. The index properties of crushed concrete like pH, specific gravity, water absorption, particle size distribution are obtained. Locally available soil is partially replaced i.e., 30%, 50%, and 70% with crushed concrete fine aggregates and its compaction characteristics and shear strength parameters are determined. In the continuation of the study, a numerical model is developed using a finite element software i.e GeoStudio Sigma/w. Mesh and boundary extent convergence studies are done for the model. The top 1m virgin soil is replaced with the mixture of CC and soils. Settlements for various percentages of CC and for different width of footing are obtained for a uniform stress of 200kPa. The stress is applied in 5 stages in order to simulate real field conditions. It was observed that 30% replacement of CC have given the least settlement for all widths of footing considered in the study

scholarly journals Effect of River Indus Sand and Recycled Concrete Aggregates as Fine and Coarse Replacement on Properties of Concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 3832-3835 ◽  
Author(s):  
A. R. Sandhu ◽  
M. T. Lakhiar ◽  
A. A. Jhatial ◽  
H. Karira ◽  
Q. B. Jamali
Keyword(s):  
Tensile Strength ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Compressive Strength Of Concrete ◽  
River Indus ◽  
Concrete Materials

As the demand for concrete rises, the concrete materials demand increases. Aggregates occupy 75% of concrete. A vast amount of aggregates is utilized in concrete while aggregate natural resources are reducing. To overcome this problem, River Indus sand (RIS) and recycled concrete aggregate (RCA) were utilized as fine and coarse aggregate respectively. The aim of this experimental investigation is to evaluate the workability, and compressive and tensile strength of concrete utilizing RIS and RCA. Concrete samples of 1:2:4 proportions were cast, water cured for 7, 14, 21 and 28 days, and tested for compressive and tensile strength. The outcomes demonstrate that concrete possessed less workability when RIS and RCA were utilized. It was predicted that compressive strength of concrete would reduce up to 1.5% when 50% RIS and 50% RCA were utilized in concrete and 11.5% when natural aggregate was fully replaced by RIS and RCA, whereas the tensile strength decreased up to 1.60% when 50% by 12% respectively.

Review of Studies concerning Effects of Unbound Crushed Concrete Bases on PCC Pavement Drainage

1996 ◽  
Vol 1519 (1) ◽  
pp. 51-58 ◽  
Author(s):  
Mark B. Snyder ◽  
James E. Bruinsma
Keyword(s):  
Drainage System ◽  
Field Studies ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Drainage Systems ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Crushed Concrete ◽  
Pavement Structures ◽  
Natural Aggregates

Recycled concrete aggregate (RCA) products are sometimes used as replacements for virgin aggregate products in concrete pavement structures. Recent concerns have centered on the deposit of RCA-associated fines and precipitate suspected of reducing the drainage capacity of RCA base layers and associated drainage systems. Environmental concerns have focused on the relatively high pH of the effluent produced by untreated RCA base layers. Several studies have examined these concerns and others; the results of some of these studies have not been published or publicized. The most relevant of these studies are summarized herein. These research efforts demonstrate that calcium-based compounds are present in most recycled concrete aggregates in quantities sufficient to be leached and precipitated in the presence of carbon dioxide. Precipitate potential appears to be related to the amount of freshly exposed cement paste surface. Thus, selective grading or blending with natural aggregates can reduce, but not eliminate, precipitate problems. It was also noted that insoluble, noncarbonate residue makes up a major portion of the materials found in and around pavement drainage systems. Washing the RCA products before using them in foundation layers appears to reduce the potential for accumulation of dust and other fines in the drainage system, but probably has little effect on precipitate potential. Field studies have shown that precipitate and insoluble materials can significantly reduce the permittivity of typical drainage fabrics but that attention to drainage design details can minimize the effects of these materials on pavement drainage.

scholarly journals Investigation of the Use of Recycled Concrete Aggregates Originating from a Single Ready-Mix Concrete Plant

2018 ◽  
Vol 8 (11) ◽  
pp. 2149 ◽  
Author(s):  
Eleftherios Anastasiou ◽  
Michail Papachristoforou ◽  
Dimitrios Anesiadis ◽  
Konstantinos Zafeiridis ◽  
Eirini-Chrysanthi Tsardaka
Keyword(s):  
Soil Stabilization ◽  
Coarse Fraction ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Hardened Concrete ◽  
Fine Aggregate ◽  
Waste Products ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Concrete Mixtures

The waste produced from ready-mixed concrete (RMC) industries poses an environmental challenge regarding recycling. Three different waste products form RMC plants were investigated for use as recycled aggregates in construction applications. Crushed hardened concrete from test specimens of at least 40 MPa compressive strength (HR) and crushed hardened concrete from returned concrete (CR) were tested for their suitability as concrete aggregates and then used as fine and coarse aggregate in new concrete mixtures. In addition, cement sludge fines (CSF) originating from the washing of concrete trucks were tested for their properties as filler for construction applications. Then, CSF was used at 10% and 20% replacement rates as a cement replacement for mortar production and as an additive for soil stabilization. The results show that, although there is some reduction in the properties of the resulting concrete, both HR and CR can be considered good-quality recycled aggregates, especially when the coarse fraction is used. Furthermore, HR performs considerably better than CR both as coarse and as fine aggregate. CSF seems to be a fine material with good properties as a filler, provided that it is properly crushed and sieved through a 75 μm sieve.

Modified recycled concrete aggregates for asphalt mixture using microbial calcite precipitation

RSC Advances ◽  
2015 ◽  
Vol 5 (44) ◽  
pp. 34854-34863 ◽  
Author(s):  
Zhong-Yao Pan ◽  
Gengying Li ◽  
Cheng-Yu Hong ◽  
Hui-Ling Kuang ◽  
Yu Yu ◽  
...  
Keyword(s):  
Bonding Strength ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Calcite Precipitation ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Porosity And Permeability

Recycled concrete aggregate (RCA) was pretreated by microbial calcite precipitation. The surface treatment reduced the porosity and permeability of RCA by 32% and 86.5%, respectively. The treatment improved the bonding strength of RCA–asphalt binder by 55%.

Experimental Study on Fundamental Characteristic of Recycled Concrete

2010 ◽  
Vol 146-147 ◽  
pp. 1925-1929
Author(s):  
Yuan Xu ◽  
Ru Heng Wang ◽  
Hua Chuan Yao
Keyword(s):  
Fly Ash ◽  
Maximum Size ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Fundamental Characteristic ◽  
Recycled Concrete Aggregate ◽  
Application Process ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Natural Rock

First, the fundamental characteristic of recycled concrete aggregate wasstudied. Then, the recycled concrete spiciemen with different maximum size was tested. The results showed that: the apparent density and bulk density of recycled concrete aggregates was smaller than the natural rock, but the moisture content, crushed index, water absorption was higher. The workability of recycled concrete improved with increase of water and fly ash, but its strength decreased as the increase of water and fly ash. The research on performance and strength of recycled concrete aggregate will provide certain theoretical basis in the application process.

scholarly journals Shrinkage and porosity in concretes produced with recycled concrete aggregate and rice husk ash

2019 ◽  
Vol 12 (3) ◽  
pp. 694-704
Author(s):  
V. CECCONELLO ◽  
B. R. C.SARTORI ◽  
M. P .KULAKOWSKI ◽  
C. S. KAZMIERCZAK ◽  
M. MANCIO
Keyword(s):  
Rice Husk ◽  
Rice Husk Ash ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Supplementary Cementitious Material ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Binder Ratio ◽  
Water To Binder Ratio

Abstract The admixture of recycled concrete aggregates (RCA) in new concretes is an interesting alternative in the efforts to mitigate environmental impacts. RCA may increase porosity and change properties of concretes. Rice husk ash (RHA) is employed as supplementary cementitious material may improve concrete properties. The present study investigated the shrinkage of concrete prepared with RCA and RHA, proposing a mathematical model to explain the phenomenon. Concretes were produced with 25% and 50% of coarse recycled aggregate as replacement of natural aggregate, 0%, 10%, and 20% of RHA as replacement of cement, and a water-to-binder ratio of 0.64. Water absorption and capillary and total porosities were analyzed on day 28. Shrinkage tests were conducted on days 1, 4, 7, 14, 28, 63, 91, and 112. The results point to a significant interaction between RHA and RCA.

Potential water pollution from recycled concrete aggregate material

2021 ◽  
Vol 72 (1) ◽  
pp. 58
Author(s):  
K. Purdy ◽  
J. K. Reynolds ◽  
I. A. Wright
Keyword(s):  
Water Contamination ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Water Pipe ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Road Base ◽  
Final Treatment ◽  
Aggregate Material

Recycled concrete aggregates (RCA) are a widely used recycled building material. RCA materials have many uses such as a road base or backfilling trenches. Our study investigated the potential water-contamination risks of water exposed to RCA materials. We recirculated water for 60min through four different treatments. Two treatments were a PVC gutter filled with different size grades of RCA material (20mm and 45mm), the third treatment was a clean PVC gutter and the fourth and final treatment was an unused concrete water pipe. Results showed that RCA material exposed to water released a suite of contaminants that could be ecologically hazardous to aquatic species. RCA leached metals over the 60-min recirculation (aluminium, arsenic, barium, chromium, lead, manganese, molybdenum, titanium, lithium and strontium). Water exposed to RCA material exceeded aquatic ecosystem guidelines for aluminium by 50 times and lead by up to 12 times. RCA materials increased pH by up to 4.35 pH units and electrical conductivity (EC) by up to 11 times the starting EC (mean 27.9 µs cm–1). We suggest that RCA materials need to be used with caution in settings that could be exposed to water and flow to waterways of conservation value.

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