scholarly journals Performance of Steel Fiber-Reinforced Alkali-Activated Slag-Fly Ash Blended Concrete Incorporating Recycled Concrete Aggregates and Dune Sand

Buildings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 327
Author(s):  
Hilal El-Hassan ◽  
Abdalla Hussein ◽  
Jamal Medljy ◽  
Tamer El-Maaddawy
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Steel Fiber ◽  
Recycled Concrete ◽  
Steel Fibers ◽  
Dune Sand ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Activated Slag ◽  
Alkali Activated

This study evaluates the performance of alkali-activated slag-fly ash blended concrete made with recycled concrete aggregates (RCA) and reinforced with steel fibers. Two blends of concrete with ground granulated blast furnace slag-to-fly ash ratios of 3:1 and 1:1 were used. Natural aggregates were substituted with RCA, while macro steel fibers with 35 mm of length and aspect ratio of 65 were incorporated in RCA-based mixtures at various volume fractions. Fine aggregates were in the form of desert dune sand. Mechanical and durability characteristics were investigated. Experimental results revealed that RCA replacement decreased the compressive strength of plain concrete mixtures with more pronounced reductions being perceived at higher replacement percentages. Mixtures made with 30%, 70%, and 100% RCA could be produced with limited loss in the design compressive strength upon incorporating 1%, 2%, and 2% steel fibers, by volume, respectively. In turn, splitting tensile strength was comparable to the NA-based control while adding at least 1% steel fiber, by volume. Moreover, higher water absorption and capillary sorptivity and lower ultrasonic pulse velocity, bulk resistivity, and abrasion resistance were reported during RCA replacement. Meanwhile, incorporation of steel fibers densified the concrete and enhanced its resistance to abrasive forces, water permeation, and water transport. Analytical regression models were developed to correlate hardened concrete properties to the 28-day cylinder compressive strength.

scholarly journals Properties of Steel Fiber-Reinforced Alkali-Activated Slag Concrete Made with Recycled Concrete Aggregates and Dune Sand

2021 ◽  
Vol 13 (14) ◽  
pp. 8017
Author(s):  
Hilal El-Hassan ◽  
Jamal Medljy ◽  
Tamer El-Maaddawy
Keyword(s):  
Compressive Strength ◽  
Steel Fiber ◽  
Recycled Concrete ◽  
Steel Fibers ◽  
Dune Sand ◽  
Alkali Activated Slag ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Activated Slag ◽  
Alkali Activated

Reutilizing industrial by-products and recycled concrete aggregates (RCA) to replace cement and natural aggregates (NA) in concrete is becoming increasingly important for sustainable development. Yet, experimental evidence is needed prior to the widespread use of this sustainable concrete by the construction industry. This study examines the performance of alkali-activated slag concrete made with RCA and reinforced with steel fibers. Natural coarse aggregates were replaced with RCA. Steel fibers were added to mixes incorporating RCA at different volume fractions. Desert dune sand was used as fine aggregate. The mechanical and durability properties of plain and steel fiber-reinforced concrete made with RCA were experimentally examined. The results showed that the compressive strength did not decrease in plain concrete mixes with 30 and 70% RCA replacement. However, full replacement of NA with RCA resulted in a 20% reduction in the compressive strength of the plain mix. In fact, 100% RCA mixes could only be produced with compressive strength comparable to that of an NA-based control mix in conjunction with 2% steel fiber, by volume. In turn, at least 1% steel fiber, by volume, was required to maintain comparable splitting tensile strength. Furthermore, RCA replacement led to higher water absorption and sorptivity and lower bulk resistivity, ultrasonic pulse velocity, and abrasion resistance. Steel fiber incorporation in RCA-based mixes densified the concrete and improved its resistance to abrasion, water permeation, and transport, thereby enhancing its mechanical properties to exceed that of the NA-based counterpart. The hardened properties were correlated to 28-day cylinder compressive strength through analytical regression models.

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.

Experimental Study on Alkali-Activated Slag-Lithium Slag-Fly Ash Environmental Concrete

2011 ◽  
Vol 287-290 ◽  
pp. 1237-1240
Author(s):  
Lan Fang Zhang ◽  
Rui Yan Wang
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Fly Ash ◽  
Setting Time ◽  
Alkali Activated Slag ◽  
Percent Increase ◽  
Compressive Strength Of Concrete ◽  
Activated Slag ◽  
Lithium Slag ◽  
Alkali Activated

The aim of this paper is to study the influence of lithium-slag and fly ash on the workability , setting time and compressive strength of alkali-activated slag concrete. The results indicate that lithium-slag and fly-ash can ameliorate the workability, setting time and improve the compressive strength of alkali-activated slag concrete，and when 40% or 60% slag was replaced by lithium-slag or fly-ash, above 10 percent increase in 28-day compressive strength of concrete were obtained.

scholarly journals Evaluation of the Ecotoxicological Potential of Fly Ash and Recycled Concrete Aggregates Use in Concrete

2020 ◽  
Vol 10 (1) ◽  
pp. 351 ◽  
Author(s):  
Patrícia Rodrigues ◽  
José D. Silvestre ◽  
Inês Flores-Colen ◽  
Cristina A. Viegas ◽  
Hawreen H. Ahmed ◽  
...  
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Daphnia Magna ◽  
Raw Materials ◽  
Construction Materials ◽  
Recycled Concrete ◽  
Experimental Program ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Natural Aggregates

This study applies a methodology to evaluate the ecotoxicological potential of raw materials and cement-based construction materials. In this study, natural aggregates and Portland cement were replaced with non-conventional recycled concrete aggregates (RA) and fly ash (FA), respectively, in the production of two concrete products alternative to conventional concrete (used as reference). The experimental program involved assessing both the chemical properties (non-metallic and metallic parameters) and ecotoxicity data (battery of tests with the luminescent bacterium Vibrio fischeri, the freshwater crustacean Daphnia magna, and the yeast Saccharomyces cerevisiae) of eluates obtained from leaching tests of RA, FA, and the three concrete mixes. Even though the results indicated that RA and FA have the ability to release some chemicals into the water and induce its alkalinisation, the respective eluate samples presented no or low levels of potential ecotoxicity. However, eluates from concrete mixes produced with a replacement ratio of Portland cement with 60% of FA and 100% of natural aggregates and produced with 60% of FA and 100% of RA were classified as clearly ecotoxic mainly towards Daphnia magna mobility. Therefore, raw materials with weak evidences of ecotoxicity could lead to the production of concrete products with high ecotoxicological potential. Overall, the results obtained highlight the importance of integrating data from the chemical and ecotoxicological characterization of materials’ eluate samples aiming to assess the possible environmental risk of the construction materials, namely of incorporating non-conventional raw materials in concrete, and contributing to achieve construction sustainability.

Sign in / Sign up

Export Citation Format

Share Document