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 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.

Effect of Steel Fiber Volume Fraction and Curing Conditions on the Compressive Behavior of Alkali-Activated Slag Concrete

2014 ◽  
Vol 525 ◽  
pp. 491-494
Author(s):  
Dae Hyun Kang ◽  
Hye Ran Kim ◽  
Hyun Do Yun
Keyword(s):  
Compressive Strength ◽  
Fiber Volume Fraction ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Compressive Behavior ◽  
Fiber Volume ◽  
Curing Conditions ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated

In this paper, an experimental investigation was carried out to examine the influence of hooked end steel fiber volume fraction and curing conditions on the compressive performance of concrete produced by using ordinary portland cement (OPC) and alkali-activated slag (AAS). Three different volume fractions of 0.5%, 1.0% and 1.5% were used in OPC and AAS concrete mixtures. Cylindrical specimens with 100 x 200mm were tested for compressive behavior of both concretes at 3, 7 and 28 days of curing age. Test results showed that curing conditions had a significant effect on compressive properties in the hardened OPC and AAS concretes. The addition of steel fibers generated a decrease in compressive strength of OPC while an increase in the compressive strength of AAS concrete was shown with adding steel fiber.

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 The Effect of Different Types of Internal Curing Liquid on the Properties of Alkali-Activated Slag (AAS) Mortar

2021 ◽  
Vol 13 (4) ◽  
pp. 2407
Author(s):  
Guang-Zhu Zhang ◽  
Xiao-Yong Wang ◽  
Tae-Wan Kim ◽  
Jong-Yeon Lim ◽  
Yi Han
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Deionized Water ◽  
Internal Curing ◽  
Control Group ◽  
Alkali Activated Slag ◽  
Different Types ◽  
Naoh Solution ◽  
Activated Slag ◽  
Alkali Activated

This study shows the effect of different types of internal curing liquid on the properties of alkali-activated slag (AAS) mortar. NaOH solution and deionized water were used as the liquid internal curing agents and zeolite sand was the internal curing agent that replaced the standard sand at 15% and 30%, respectively. Experiments on the mechanical properties, hydration kinetics, autogenous shrinkage (AS), internal temperature, internal relative humidity, surface electrical resistivity, ultrasonic pulse velocity (UPV), and setting time were performed. The conclusions are as follows: (1) the setting times of AAS mortars with internal curing by water were longer than those of internal curing by NaOH solution. (2) NaOH solution more effectively reduces the AS of AAS mortars than water when used as an internal curing liquid. (3) The cumulative heat of the AAS mortar when using water for internal curing is substantially reduced compared to the control group. (4) For the AAS mortars with NaOH solution as an internal curing liquid, compared with the control specimen, the compressive strength results are increased. However, a decrease in compressive strength values occurs when water is used as an internal curing liquid in the AAS mortar. (5) The UPV decreases as the content of zeolite sand that replaces the standard sand increases. (6) When internal curing is carried out with water as the internal curing liquid, the surface resistivity values of the AAS mortar are higher than when the alkali solution is used as the internal curing liquid. To sum up, both NaOH and deionized water are effective as internal curing liquids, but the NaOH solution shows a better performance in terms of reducing shrinkage and improving mechanical properties than deionized water.

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