scholarly journals Development and Guidance of Green Concrete for Leed™ Applications

2010 ◽  
Vol 5 (4) ◽  
pp. 111-120
Author(s):  
John T Kevern
Keyword(s):  
Green Building ◽  
Cementitious Materials ◽  
Recycled Concrete ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregate ◽  
Strength Development ◽  
Concrete Aggregate ◽  
Total Contribution ◽  
Recycled Materials ◽  
Concrete Mixtures

As green building rating systems such as LEED™ become more popular, the use of recycled materials in construction is increasing. Concrete can be produced with significant quantities of supplementary cementitious materials or recycled aggregate materials. However, modifying concrete mixture proportions for improved recycled content credits also impacts strength and long-term durability. Without properly understanding the effects recycled materials have on concrete, greener concrete can be less desirable from a lifecycle perspective from poor durability. This research investigates the impacts different types and quantities of supplementary cementitious materials and recycled concrete aggregate have on strength development and concrete durability, specifically deicer scaling. Improvements to deicer scaling resistance were investigated using a novel soybean oil sealer. The concrete mixtures were also evaluated within the LEED™ recycled materials criteria for selection based on economy and total contribution value. Considerations are included to assist designers in the selection of greener concrete mixtures for appropriate applications.

scholarly journals Long-term performance of sustainable pavements using ternary blended concrete with recycled aggregates

2021 ◽  
Author(s):  
Gilson Lomboy ◽  
Douglas Cleary ◽  
Seth Wagner ◽  
Yusef Mehta ◽  
Danielle Kennedy ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cementitious Materials ◽  
Recycled Concrete ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Concrete Aggregates ◽  
Concrete Mixtures

Dwindling supplies of natural concrete aggregates, the cost of landfilling construction waste, and interest in sustainable design have increased the demand for recycled concrete aggregates (RCA) in new portland cement concrete mixtures. RCA repurposes waste material to provide useful ingredients for new construction applications. However, RCA can reduce the performance of the concrete. This study investigated the effectiveness of ternary blended binders, mixtures containing portland cement and two different supplementary cementitious materials, at mitigating performance losses of concrete mixtures with RCA materials. Concrete mixtures with different ternary binder combinations were batched with four recycled concrete aggregate materials. For the materials used, the study found that a blend of portland cement, Class C fly ash, and blast furnace slag produced the highest strength of ternary binder. At 50% replacement of virgin aggregates and ternary blended binder, some specimens showed comparable mechanical performance to a control mix of only portland cement as a binder and no RCA substitution. This study demonstrates that even at 50% RCA replacement, using the appropriate ternary binder can create a concrete mixture that performs similarly to a plain portland cement concrete without RCA, with the added benefit of being environmentally beneficial.

scholarly journals Influence of additives on properties of concrete with recycled aggregate and fly ash

2018 ◽  
Vol 196 ◽  
pp. 04085
Author(s):  
Małgorzata Wydra
Keyword(s):  
Fly Ash ◽  
Cementitious Materials ◽  
Recycled Concrete ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Environmental Friendliness ◽  
Concrete Production ◽  
Air Void

It is possible to considerably enhance the environmental friendliness of concrete production by increasing the usage of recycled concrete aggregate (RCA) and supplementary cementitious materials (SCM) in concrete industry [1, 2]. The idea of concrete with recycled concrete aggregate (RCA), additives such as microsilica, metakaolin, fluidized fly ash and superplasticizers might be controversial - it assumes usage of waste material and expensive additives - it is popular though. The aim of this paper was to determine, what the frost resistance of such concrete is. Additionally tests of other properties (sorptivity, absorbability and air void parameters) were performed.

Improving the Durability of High Early Strength (HES) Concrete Patching Materials for Concrete Pavements

2020 ◽  
Vol 2674 (8) ◽  
pp. 12-23
Author(s):  
Cameron Wilson ◽  
W. Jason Weiss
Keyword(s):  
Cement Content ◽  
Autogenous Shrinkage ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Development ◽  
Concrete Pavements ◽  
Shrinkage Cracking ◽  
Concrete Mixtures ◽  
Water To Cement Ratio ◽  
Early Strength

High early strength (HES) concrete patching materials are increasingly used to repair damaged pavements. The use of HES concrete enables the repaired pavement to be opened to traffic shortly after the repair has been installed; for example, opening pavements to traffic 4–6 h after the concrete is placed is becoming more common. HES concrete mixtures are typically designed with a low water-to-cement ratio and a high cement content; they contain accelerating admixtures and limited supplementary cementitious materials. As a result, these HES patches may be susceptible to self-desiccation, causing autogenous shrinkage and early age cracking. Self-desiccation can lead to reduced hydration, limited strength gain, and overestimation of strength development in maturity-based predictions. The objectives of this study are threefold. First, the paper will illustrate how self-desiccation can lead to the premature cessation of hydration and increased potential for shrinkage cracking. Second, the paper will illustrate how maturity-based predictions can be modified to account for self-desiccation. Third, internal curing is discussed as a way to mitigate self-desiccation and shrinkage ultimately improving the performance of HES concrete patching materials.

Study on Properties of Self-Compacting Concrete Prepared with Coarse Recycled Concrete Aggregate

2014 ◽  
Vol 638-640 ◽  
pp. 1494-1498 ◽  
Author(s):  
Jian Jie Yu ◽  
Jian Gong ◽  
Jie Ming Zou ◽  
Wei Kang Yang
Keyword(s):  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Working Environment ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Self Compacting Concrete ◽  
Recycled Coarse Aggregate ◽  
Concrete Mixtures ◽  
Crushed Concrete ◽  
Construction Efficiency

Self-compacting concrete is absent of vibration noise during casting, improves the construction efficiency, and provides a healthier working environment compared to the traditional vibrated concrete. The potential coarse recycled aggregate obtained from crushed concrete for making self-compacting concrete was considered to replace the aggregate with the percentage of substitution of recycled coarse aggregate 0%, 50% and 100%. Thus, three types of concrete mixtures were made. Experiments show that, the properties of these concrete only have slight differences and recycled coarse aggregate can be successfully used for the preparation of self-compacting concrete. The method solves the problem of the waste disposal by the demolition of old buildings.

scholarly journals Structural Concrete Prepared with Coarse Recycled Concrete Aggregate: From Investigation to Design

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Valeria Corinaldesi
Keyword(s):  
Elastic Modulus ◽  
Drying Shrinkage ◽  
Structure Design ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Structural Concrete ◽  
Aggregate Fraction ◽  
Concrete Mixtures

An investigation of mechanical behaviour and elastic properties of recycled aggregate concrete (RAC) is presented. RACs were prepared by using a coarse aggregate fraction made of recycled concrete coming from a recycling plant in which rubble from concrete structure demolition is collected and suitably treated. Several concrete mixtures were prepared by using either the only virgin aggregates (as reference) or 30% coarse recycled aggregate replacing gravel and by using two different kinds of cement. Different water-to-cement ratios were adopted ranging from 0.40 to 0.60. Concrete workability was always in the range 190–200 mm. 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 from experimentation were discussed in order to obtain useful information for RAC structure design, particularly in terms of elastic modulus and drying shrinkage prediction.

scholarly journals PROPERTIES OF RECYCLED AGGREGATE CONCRETE

2014 ◽  
Vol 5 (2) ◽  
Author(s):  
Mirjana Malešev ◽  
Vlastimir Radonjanin ◽  
Gordana Broćeta
Keyword(s):  
Great Powers ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Demolition Waste ◽  
Aggregate Concrete ◽  
Recycling Industry ◽  
Concrete Mixtures

Following an example of the world's great powers that developed the recycling industry after natural disasters and wars, the paper points to the possibility of using large quantities of construction and demolition waste, generated as a result of the recent floods in the BiH and Serbia. Based on the years of extensive experimental research, and the research conducted by eminent experts, an overview is provided of the most basic properties and application of recycled aggregate concrete. It has been shown that the application of coarse recycled concrete aggregate, as the component materials in the concrete mixtures, it is possible to produce structural concrete that can be satisfactory and even with high quality, which primarily depends on the characteristics of crushed demolished concrete.

Effect of Water Reducing Admixtures and Construction Variability in Concrete Containing Recycled Aggregate Concrete

2021 ◽  
Vol 47 (3) ◽  
pp. 456-464
Author(s):  
Claude Villiers
Keyword(s):  
Compressive Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Target Strength ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Effect Of Water ◽  
Concrete Mixtures ◽  
Concrete Mix

The objectives of this project are to evaluate the effect of water reducing admixtures and construction variability in concrete mixtures containing recycled concrete aggregate (RCA). A concrete mix that was approved for curbs and sidewalks in the State of Florida was selected. Based on the analysis conducted, it was found that properties of the RCA were comparable to the virgin aggregate used in this project. However, the absorption of the RCA was double as compared to the limestone. Although the compressive strength of the virgin mix was decreased by 19% when RCA was introduced into the mix, both mixes met the target strength (17.2 MPa). Admixture has a significant impact on all the mixes, especially on mixes that contained RCA. When admixture was omitted, the 28-day compressive strength dropped to nearly 55% on the mixture containing RCA. In addition, the RCA mix without the admixture did not reach the target strength at 28 days. Similarly, construction variability has a significant effect on the compressive strength of the mixes. When the RCA content was increased by 15% and 25% respectively, the concrete paste was weak. These mixtures did not meet the target strength at 28 days.

Understanding the effect of recycled concrete aggregate and cementitious materials on concrete's fire resistance

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammed Ahmed Abed ◽  
Eva Lubloy
Keyword(s):  
Fly Ash ◽  
High Temperatures ◽  
Fire Resistance ◽  
Blended Cement ◽  
Cementitious Materials ◽  
Recycled Concrete ◽  
Supplementary Cementitious Materials ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Content Type

PurposeFire can severely affect concrete structures and with knowledge of the properties of materials, the damage can be assessed. Aggregate, cement matrix and their interaction are the most important components that affect concrete behaviour at high temperatures. The effect of incorporating recycled concrete aggregate or cementitious materials, namely, cement type and pulverized fly ash, are reviewed to provide a better understanding of their involvement in fire resistance.Design/methodology/approachMore investigation research is needed to understand the fire resistance of such sustainable concrete that was already constructed. The present study illustrates the effect of using recycled concrete aggregate and cementitious materials on the fire resistance of concrete. To do so, a literature review was conducted and relevant data were collected and presented in a simple form. The author's selected research findings, which are related to the presents study, are also presented and discussed.FindingsRecycled concrete aggregate enhances the concrete behaviour at high temperatures when it substitutes the natural aggregate by reasonable substitution (more than 25–30%). It also almost eliminates the possibility of spalling. Moreover, utilizing both supplementary cementitious materials with recycled concrete aggregate can improve the fire resistance of concrete. The incorporation of pulverized fly ash and slag in Portland cement or blended cement can generally keep the mechanical properties of concrete at a higher level after heating to a high temperature.Originality/valueRecycled concrete aggregate enhances the concrete behaviour at high temperatures when it substitutes the natural aggregate by reasonable substitution (more than 25–30%). It also almost eliminates the possibility of spalling. Moreover, utilizing both supplementary cementitious materials with recycled concrete aggregate can improve the fire resistance of concrete. The incorporation of pulverized fly ash and slag in Portland cement or blended cement can generally keep the mechanical properties of concrete at a higher level after heating to a high temperature.

scholarly journals The influence of RCA addition on selected parameters of concrete

2018 ◽  
Vol 196 ◽  
pp. 02018
Author(s):  
Roman Jaskulski ◽  
Marcin Supera ◽  
Wojciech Kubissa ◽  
Peter Koteš ◽  
Miroslav Brodňan
Keyword(s):  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Test Results ◽  
Recycled Concrete Aggregate ◽  
Average Quality ◽  
Durability Test ◽  
Natural Aggregate ◽  
Concrete Mixtures

The main goal of this research was to evaluate the effects of using recycled concrete aggregate (RCA) of an average quality as a 50% replacement for natural coarse aggregate. A total of 26 concrete mixtures were prepared, 13 containing RCA as a 50% of coarse aggregate and the same number of mixes only with natural aggregate (NA). The results show the influence of the RCA incorporation on concretes for the same w/c ratio. Both mechanical and durability parameters of the concretes made with recycled aggregate are worse, and the differences increase for low w/c ratio. Despite the reduction of these parameters in relation to concretes with only NA, both mechanical and durability test results obtained for concrete series with RCA can be described as good.

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