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

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.

2014 ◽  
Vol 525 ◽  
pp. 469-472 ◽  
Author(s):  
Yeon Jun Yun ◽  
Kyung Lim Ahn ◽  
Won Gyun Lim ◽  
Hyun Do Yun

This paper describes the experimental results on compressive and flexural behavior of alkali-activated slag (AAS) concrete reinforced with hooked end steel fiber. Two different fiber volume fractions of 0.5 and 1.0% were used for AAS concrete and Ordinary Portland cement (OPC) concretes were also mixed for comparison. Test results indicated that compressive and flexural performance of AAS concretes with water-to-binder (W/B) ratio of 0.55 are equivalent to those of OPC concrete. The addition of steel fiber to AAS concrete improves more compressive and flexural performance than those of steel fiber reinforced concrete.


2021 ◽  
Vol 13 (14) ◽  
pp. 8017
Author(s):  
Hilal El-Hassan ◽  
Jamal Medljy ◽  
Tamer El-Maaddawy

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.


Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3513 ◽  
Author(s):  
Yubin Jun ◽  
Seong Ho Han ◽  
Tae Yong Shin ◽  
Jae Hong Kim

The effect of CO2 curing on alkali-activated slag paste activated by a mixture of sodium hydroxide and sodium silicate solutions is reported in this paper. The paste samples after demolding were cured in three different curing environments as follows: (1) environmental chamber maintained at 85% relative humidity (RH) and 25 °C; (2) 3-bar CO2 pressure vessel; and (3) CO2 chamber maintained at 20% CO2 concentration, 70% RH and 25 °C. The hardened samples were then subjected to compressive strength measurement, X-ray diffraction analysis, and thermogravimetry. All curing conditions used in this study were beneficial for the strength development of the alkali-activated slag paste samples. Among the curing environments, the 20% CO2 chamber was the most effective on compressive strength development; this is attributed to the simultaneous supply of moisture and CO2 within the chamber. The results of X-ray diffraction and thermogravimetry show that the alkali-activated slag cured in the 20% CO2 chamber received a higher amount of calcium silicate hydrate (C-S-H), while calcite formed at an early age was consumed with time. C-S-H was formed by associating the calcite generated by CO2 curing with the silica gel dissolved from alkali-activated slag.


2016 ◽  
Vol 709 ◽  
pp. 101-104 ◽  
Author(s):  
Seok Joon Jang ◽  
Gwon Young Jeong ◽  
Mi Hwa Lee ◽  
Keitetsu Rokugo ◽  
Hyun Do Yun

This paper presents results of experimental investigation to evaluation the effects of compressive strength on flexural behavior of steel fiber-reinforced concrete (SFRC). For this purpose, normal and high strength SFRCs with two different fiber volume fractions of 0.5 and 1.0% were prepared. Compressive strength, modulus of elasticity, flexural strength and toughness were measured with tests on SFRC cylinders and prisms. Test results indicated that steel fiber volume fraction significantly affects the flexural strength and toughness of SFRC. However, the high strength SFRC showed reduction in flexural toughness compared with the normal strength SFRC. It can be concluded that flexural behavior of SFRC depends on both compressive strength and fiber volume fraction.


2021 ◽  
Vol 13 (4) ◽  
pp. 2407
Author(s):  
Guang-Zhu Zhang ◽  
Xiao-Yong Wang ◽  
Tae-Wan Kim ◽  
Jong-Yeon Lim ◽  
Yi Han

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.


2011 ◽  
Vol 287-290 ◽  
pp. 1237-1240
Author(s):  
Lan Fang Zhang ◽  
Rui Yan Wang

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.


2019 ◽  
Vol 803 ◽  
pp. 262-266
Author(s):  
Osama Ahmed Mohamed ◽  
Maadoum M. Mustafa

Alkali activated slag (AAS) offers opportunities to the construction industry as an alternative to ordinary Portland cement (OPC). The production of OPC and its use contributes significantly to release of CO2 into the atmosphere while AAS is an industrial by-product that contributes much less to the environmental footprint that needs to be recycled if not landfilled. This paper outlines some of the key properties, merits and demerits of AAS when used as alternative to OPC. Competitive compressive strength of AAS concrete is amongst of the advantages of replacing cement with AAS while high shrinkage and carbonation levels are potential disadvantages.


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