Compressive Strength Performance of Alkali Activated Concretes under Different Curing Conditions

This research provides an experimental investigation on the properties of fiber reinforced composite materials consisting of lightweight expanded clay aggregates (LECA) and polyvinyl alcohol (PVA) fibers. The influence of temperature (room temperature, 250°C, and 500°C) on the lightweight geopolymer mortar (LWGM) composite materials is also explored. LECA is used as a partial replacement to river sand with 60% and 80%. The base material utilized for LWGM is slag activated by a mixture of sodium silicate and sodium hydroxide solutions. The fresh properties in terms of workability and density were performed. A series of experiments, such as compression, flexural and uniaxial tensile strength tests, were executed to assess the mechanical properties of LWGM composite materials. In addition, the microscopic variations due to the elevated temperature were also evaluated by scanning electron microscopy (SEM) to understand the macro-scale behavior of the samples. The results indicated that increasing the level of LECA replacement caused a reduction in the density and compressive strength of the LWGM. Also, incorporating a 1% PVA fiber volume fraction significantly enhanced the flexural and uniaxial tensile behavior of LWGM composite materials. The compressive strength enhancements were observed at 250°C due to further geopolymerization, while compressive strength reductions were obtained at 500°C due to the vapor impact and difference in thermal expansion. In addition, the load-carrying capacity of all samples increased, and displacement capacity decreased under flexural tests at 250°C. However, the ductile behavior of the PVA incorporating specimens changed to brittle due to the melting of PVA fibers.

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“…For the workability enhancement and further geopolymerization, additional water is also utilized in the mixes. 26…”

Section: Methodsmentioning

confidence: 99%

Residual mechanical performance of lightweight fiber-reinforced geopolymer mortar composites incorporating expanded clay after elevated temperatures

Aljanabi

Çevik

Niş

et al. 2022

Journal of Composite Materials

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“…The produced rubberized samples were demolded after 24 h later and then kept in the laboratory medium at 23 ± 2•C at the ages of 28 days. In the previous investigation, it was reported that slag-based alkali activated concretes can be utilized in structural applications without oven-curing or water curing [22]. Therefore, oven-curing or water curing was not applied to the specimens.…”

Section: Curing Methods Of the Rubberized Scaac Samplesmentioning

confidence: 99%

The The Effects of Recycled Tire Rubbers and Steel Fibers on the Performance of Self-compacting Alkali Activated Concrete

Eren

Alzeebaree

Çevik

et al. 2021

Period. Polytech. Civil Eng.

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In this study, the effects of recycled tire rubbers (RTR) and steel fiber (SF) on the fresh and hardened state properties of the self-compacted alkali activated concrete (SCAAC) were investigated. The ground granulated blast furnace slag, 1 % hooked-end SF, and two types of RTR were utilized. The crumb rubbers (CR) and tire rubber chips (TCR) were used as a substation to natural aggregates at substation levels of 10 % and 15 %. The fresh state performances were evaluated by T50 value, slump flow, V-funnel, and L-Box tests, while mechanical performances were assessed through compressive, flexural, and splitting tensile strength tests. Also, detailed crack and microstructural analyses were conducted. The RTR adversely affected the fresh state properties, which reduced more with SF inclusions. Among the RTR, the TR specimens exhibited lower fresh state performance than the CR specimens. Similar mechanical strengths were obtained on the TR and CR specimens under the same replacement ratios. However, TR specimens exhibited higher deformation capacities than the CR specimens, when SF was utilized. The SCAAC specimens with 1 % SF and 15 % RTR showed more and wider flexural cracks, higher mechanical strength, and deformation capacity, which can be utilized in structural applications, particularly in high seismic zones.

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“…For low calcium-based systems, water curing could cause material strength reduction and alkaline cation leaching [66]. In high-calcium-based systems, water immersion can have the opposite effect, resulting in high compressive strength [67] and lower permeability [68]. The difference is mainly caused by the rapid formation of the silica-rich matrix, including calcium silicate hydrate (C-S-H) in the pore space within high calcium mixtures through water consumption, which contributes to the early strength formation [69][70][71].…”

Section: Curing Conditionsmentioning

confidence: 99%

Influence Factors in the Wide Application of Alkali-Activated Materials: A Critical Review about Efflorescence

et al. 2022

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Applications related to alkali-activated materials (AAMs) have received much attention due to their excellent mechanical properties and low-energy production. Although much research has focused on developing AAMs, their application is still limited. One of the primary reasons is the efflorescence. Not only does efflorescence affect the material aesthetics, but it also affects the mechanical performance, leading to a decrease in material quality. This paper first summarizes the current research on AAMs efflorescence. The formation process of efflorescence is divided into three parts: alkaline cation leaching, air carbonation, and efflorescence formation. Furthermore, the influences caused by different factors, including raw materials, curing conditions, AAMs modalities, etc., on the efflorescence are proposed. This paper highlights the solutions for efflorescence by avoiding free alkaline cation leaching and preventing air carbonation. The advantages and disadvantages of efflorescence are discussed in-depth, showing that it can be exploited under certain conditions, such as in wastewater treatment. This paper has important implications for the practical preparation and application of AAMs.

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Compressive Strength Performance of Alkali Activated Concretes under Different Curing Conditions

Cited by 12 publications

References 31 publications

Residual mechanical performance of lightweight fiber-reinforced geopolymer mortar composites incorporating expanded clay after elevated temperatures

Residual mechanical performance of lightweight fiber-reinforced geopolymer mortar composites incorporating expanded clay after elevated temperatures

The The Effects of Recycled Tire Rubbers and Steel Fibers on the Performance of Self-compacting Alkali Activated Concrete

Influence Factors in the Wide Application of Alkali-Activated Materials: A Critical Review about Efflorescence

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