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

2021 ◽  
Author(s):  
Necip Altay Eren ◽  
Radhwan Alzeebaree ◽  
Abdulkadir Çevik ◽  
Anıl Niş ◽  
Alaa Mohammedameen ◽  
...  
Keyword(s):  
Granulated Blast Furnace Slag ◽  
Structural Applications ◽  
Fresh State ◽  
Hardened State ◽  
Strength And Deformation ◽  
Natural Aggregates ◽  
Mechanical Performances ◽  
Mechanical Strengths ◽  
Alkali Activated Concrete ◽  
Alkali Activated

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.

scholarly journals Experimental Evaluation of the Mechanical Strengths and the Thermal Conductivity of GGBFS and Silica Fume Based Alkali-Activated Concrete

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7717
Author(s):  
Eliana Parcesepe ◽  
Rosa Francesca De Masi ◽  
Carmine Lima ◽  
Gerardo Maria Mauro ◽  
Giuseppe Maddaloni ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silica Fume ◽  
Raw Materials ◽  
Carbon Dioxide Emission ◽  
Experimental Tests ◽  
Ambient Conditions ◽  
Environmental Aspect ◽  
Mechanical Strengths ◽  
Alkali Activated Concrete ◽  
Alkali Activated

Alkali-activated concrete (AAC) could be a solution to use a cement-less binder and recycled materials for producing concrete reducing the carbon dioxide emission and the demand for raw materials, respectively. In addition to the environmental aspect, AACs can achieve mechanical characteristics higher than those of ordinary Portland concrete (OPC) but also an improvement of the thermal insulation capacity. Despite the positive results available in the scientific literature, the use of AACs in construction practice is still limited mainly due to the absence of codification for the mix design and consequently of specific design rules. In this paper, AAC produced by ground-granulated blast-furnace slag (GGBFS) and silica fume is investigated for the production of structural elements and to discuss the reliability of formulations for evaluating mechanical properties, necessary for structural design. The mechanical strengths (compression strength, tensile strength, flexural strength) are evaluated by experimental tests according to different curing times (7, 14, 28, 90 days) in ambient conditions and the thermal conductivity is measured to understand the effect that the material could have on thermal losses for a sustainable building perspective. The results showed that AAC strengths depend on the curing time and the exposure conditions, and the insulation properties can be improved compared to the traditional Portland cement with the proposed composition.

scholarly journals A study of alkali-activated concrete mixes with ground granulated blast furnace slag

2018 ◽  
Vol 20 (2) ◽  
pp. 208-215
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Statistical Significance ◽  
Alkali Activation ◽  
Curing Conditions ◽  
Granulated Blast Furnace Slag ◽  
Number Of Factors ◽  
Furnace Slag ◽  
Alkali Activated Concrete ◽  
Alkali Activated

The paper presents a laboratory study of concrete mixes based on the alkali-activation of an industrial by-product, ground granulated blast furnace slag (GGBS). A number of factors potentially affecting the resulting concrete quality in terms of workability and strengths were investigated (namely activator type, molarity, curing conditions and times). The statistical significance of the effect of these factors was supported by ANOVA. Higher workability and strengths (with lower activator concentrations) were obtained for KOH containing mixes. Curing at constant moisture and ambient temperature was successful for most alkaline activators and mixes, which showed good concrete strengths at all curing times; when Na2SiO3 was used in addition to NaOH or KOH activators of moderate to high molarity, strengths exceeded those of Ordinary Portland Cement (CEM-I) concrete of a similar water/cement ratio.

Fresh and hardened state performance of self-compacting slag based alkali activated concrete using nanosilica and steel fiber

2021 ◽  
pp. 002199832110323
Author(s):  
Necip Altay Eren ◽  
Radhwan Alzeebaree ◽  
Abdulkadir Çevik ◽  
Anıl Niş ◽  
Alaa Mohammedameen ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Aspect Ratio ◽  
Failure Modes ◽  
Steel Fiber ◽  
Specimen Thickness ◽  
Shear Cracks ◽  
Fresh State ◽  
Hardened State ◽  
Alkali Activated

This study investigates the fresh and hardened state performance of slag-based self-compacting alkali-activated concretes (SCAAC) reinforced with steel fibers (SF) and nano-silica (NS), cured at an ambient temperature. Two different hooked-end SF with two fiber volumes and NS were used to examine the combined effect of the SF volume ratio, SF aspect ratio, and NS on the fresh and hardened state performance of SCAAC. In extension, the influence of specimen thickness to steel fiber length (d/FL) ratio on the failure modes of the bending specimens was evaluated. The fresh state properties were evaluated via T50 value, slump flow, V-funnel, and L-Box tests, while the hardened state properties were studied through compressive strength, splitting tensile strength, modulus of elasticity, and flexural tensile strength tests. The relationship analyses were carried out among fresh and hardened state properties, and scanning electron microscopy (SEM) was also conducted to examine the microstructure. The results indicated that fresh state performance was favorably affected by NS inclusion but adversely influenced by SF content and aspect ratio. The hardened state performances enhanced with a higher amount of SF volume and an aspect ratio. Also, the NS improved the splitting tensile and flexural strength but decreased the compressive strength and elasticity modulus of the specimens. The d/FL ratio was found a significant parameter on failure modes, and the specimens having a d/FL ratio of 3.33 showed flexural cracks. In contrast, the specimens having a d/FL ratio of 1.25 exhibited inclined flexural-shear cracks, especially for 1% SF.

Experimental and Numerical Characterization of Self-Compacting Concrete «Using Construction Waste»

2015 ◽  
Vol 749 ◽  
pp. 353-357 ◽  
Author(s):  
Hassiba Hermime ◽  
Youcef Bouafia ◽  
Sarah Benakli
Keyword(s):  
Shear Force ◽  
Mechanical Tests ◽  
Test Results ◽  
Numerical Characterization ◽  
Fresh State ◽  
Hardened State ◽  
Mechanical Performances ◽  
Direct Tensile ◽  
Direct Tensile Test

This work carries an experimental study on the composition and the characterization of the self-compacting concretes made starting from waste of construction with comparisons which were made by contribution with the vibrated concrete. Studies on the workability and the compactness of material were made and this in a fresh state and a hardened state. Five different mechanical tests were performed: compression, direct tensile, splitting tensile, 3 points binding and failure to the shear force. Confrontations of the test results compared to formulas for calculating the shear force were realized. All the test results showed an increase in terms of resistance for SCC contribution to the VC, except the direct tensile test which gave values slightly lower. The SCC improves the failure load notably and gives better mechanical performances.

scholarly journals Construction and Demolition Waste as Recycled Aggregates in Alkali-Activated Concretes

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4016 ◽  
Author(s):  
Zahra Abdollahnejad ◽  
Mohammad Mastali ◽  
Mahroo Falah ◽  
Tero Luukkonen ◽  
Mehran Mazari ◽  
...  
Keyword(s):  
Construction And Demolition Waste ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
High Calcium ◽  
High Calcium Concentration ◽  
One Step ◽  
Hardened State ◽  
Global Construction ◽  
Alkali Activated Concrete ◽  
Alkali Activated

The growth of global construction has contributed to an inevitable increase in the amount of construction and demolition (C&D) waste, and the recycling of C&D waste as aggregates in concrete is receiving increased interest, resulting in less demand for normal aggregates and bringing a potential solution for the landfilling of wastes. Recently, several studies have focused on the use of C&D waste in alkali-activated concrete to move one step closer to sustainable concretes. This paper focuses on the main mechanisms of using C&D waste in the resulting physical, mechanical, and durability properties of alkali-activated concrete in fresh and hardened state properties. The main difficulties observed with recycled aggregates (RA) in concrete, such as high levels of water demand, porous structure, and low mechanical strength, occur in RA alkali-activated concretes. These are associated with the highly porous nature and defects of RA. However, the high calcium concentration of RA affects the binder gel products, accelerates the hardening rate of the concrete, and reduces the flowability of alkali-activated concretes. For this reason, several techniques have been investigated for modifying the water content and workability of the fresh matrix and for treating RA and RA/alkali-activated binder interactions to produce more sustainable alkali-activated concretes.

scholarly journals Implementation of Interaction Diagram of the Properties in Fresh for Mortars with Ceramic Aggregates

2016 ◽  
Vol 61 (2) ◽  
pp. 335 ◽  
Author(s):  
Francisca Guadalupe Cabrera-Covarrubias ◽  
José Manuel Gómez-Soberón ◽  
Jorge Luis Almaral-Sánchez ◽  
Ramón Corral-Higuera ◽  
María Consolación Gómez-Soberón
Keyword(s):  
Statistical Analysis ◽  
Regression Coefficients ◽  
Design Phase ◽  
Construction Sector ◽  
Demolition Waste ◽  
Interaction Diagram ◽  
Fresh State ◽  
Hardened State ◽  
Natural Aggregates ◽  
Representative Material

As the natural resources needed for the construction sector arelimited, new practices are being adopted for the managementof waste generated nowadays, including the use of constructionand demolition waste as aggregates for concrete and mortar.Considering the different typologies in construction wastes,ceramics are the second most representative material; thereforeit is important to validate their feasibility as a total orpartial replacement of natural aggregates. This work presentsa study of the properties in fresh state (consistency, density andair content) of mortars containing aggregates obtained fromrecycled ceramics, and their influence on the subsequent propertiesin the hardened state. A statistical analysis of experimentaldata was carried out by establishing regression coefficients,and then a triple-entry graph was obtained, allowing the differentproperties of mortars to be easily linked and simplifyingthe prediction of the relationships they will present since themixture design phase. 

scholarly journals Optimizing Precursors and Reagents for the Development of Alkali-Activated Binders in Ambient Curing Conditions

2021 ◽  
Vol 5 (2) ◽  
pp. 59
Author(s):  
Dhruv Sood ◽  
Khandaker M. Anwar Hossain
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Curing Conditions ◽  
Granulated Blast Furnace Slag ◽  
Hardened State ◽  
Alkali Activated Binders ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Ambient Curing

Alkali-activated binders (AABs) are developed through the activation of aluminosilicate-rich materials using alkaline reagents. The characteristics of AABs developed using a novel dry-mixing technique incorporating powder-based reagents/activators are extensively explored. A total of forty-four binder mixes are assessed in terms of their fresh and hardened state properties. The influence of mono/binary/ternary combinations of supplementary cementitious materials (SCMs)/precursors and different types/combinations/dosages of powder-based reagents on the strength and workability properties of different binder mixes are assessed to determine the optimum composition of precursors and the reagents. The binary (55% fly ash class C and 45% ground granulated blast furnace slag) and ternary (25% fly ash class C, 35% fly ash class F and 40% ground granulated blast furnace slag) binders with reagent-2 (calcium hydroxide and sodium sulfate = 2.5:1) exhibited desired workability and 28-day compressive strengths of 56 and 52 MPa, respectively. Microstructural analyses (in terms of SEM/EDS and XRD) revealed the formation of additional calcium aluminosilicate hydrate with sodium or mixed Ca/Na compounds in binary and ternary binders incorporating reagent-2, resulting in higher compressive strength. This research confirms the potential of producing powder-based cement-free green AABs incorporating binary/ternary combinations of SCMs having the desired fresh and hardened state properties under ambient curing conditions.

ESTUDO DE VIABILIDADE TÉCNICA DA APLICAÇÃO DA ESCÓRIA GRANULADA DE ALTO-FORNO EM SUBSTITUIÇÃO AO AGREGADO MIÚDO NA COMPOSIÇÃO DO CONCRETO

2021 ◽  
Vol 17 (2) ◽  
pp. 47-69
Author(s):  
Anderson Buss Woeffel ◽  
Matheus Laureth Batista
Keyword(s):  
Blast Furnace ◽  
Raw Materials ◽  
Fine Aggregate ◽  
Unsatisfactory Result ◽  
Granulated Blast Furnace Slag ◽  
Fresh State ◽  
Hardened State ◽  
Granulated Slag ◽  
Social Environmental ◽  
Furnace Slag

The macro sector of the civil construction industry is a major consumer of natural resources and it generates impacts, identified as social, environmental or economic, and it is necessary to develop studies that aim to rationalize this raw materials consumption and reduce the impacts generated. Since some resources used in the sector are finite, this work’s main objective is to make the concrete more ecological by replacing part of the fine aggregate of its composition for granulated slag from the blast furnace, reducing the need for sand extraction. For this study, tests were carried out with the co-product and with the fine aggregate, evaluating the properties of the concrete in the fresh and hardened states in three mixture types, the first being a reference, the second with 30% replacement and the third with 60% replacement of fine aggregate with slag. Based on the results obtained, it is noted that the granulated blast furnace slag has more similar characteristics to the sand’s; in the fresh state, the concrete showed a similar result in the three mix types; in the hardened state, it was observed that the performance of the concrete in axial compression was satisfactory; while in flexion traction the two proposed mixtures with substitution presented an unsatisfactory result.

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