Effect of binder content and recycled concrete aggregate on freeze-thaw and sulfate resistance of GGBFS based geopolymer concretes

2021 ◽  
Vol 301 ◽  
pp. 124246
Author(s):  
Ayşe İlayda Uğurlu ◽  
Mehmet Burhan Karakoç ◽  
Ahmet Özcan
Keyword(s):  
Binder Content ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Freeze Thaw ◽  
Sulfate Resistance

scholarly journals Desempenho de misturas asfálticas recicladas mornas e sua influência no dimensionamento do revestimento asfáltico

2020 ◽  
Vol 41 (2) ◽  
pp. 157
Author(s):  
Fernanda Gadler ◽  
Leonardo Fagundes Rosemback Miranda ◽  
Joe Villena
Keyword(s):  
Resilient Modulus ◽  
Asphalt Pavement ◽  
Asphalt Binder ◽  
Binder Content ◽  
Asphalt Mixtures ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Reclaimed Asphalt Pavement ◽  
Recycled Concrete Aggregate ◽  
Reclaimed Asphalt

The main purpose is to evaluate the performance of asphalt regarding resilient modulus and fatigue curve.The asphalt was produced with two wastes, reclaimed asphalt pavement (RAP) and recycled concrete aggregate (RCA), using the technique of warm mixtures. The evaluation includes, based on these parameters, the thickness differences in the design of asphalt layer for each mixture. Five asphalt mixtures were produced with incorporation of RAP and RCA, in different gradation fractions (fine and/or course), without adding any natural aggregate. In view of the aim of the article, the mixtures were evaluated through tests of resilient modulus and fatigue life, in order to support the design, establishing the necessary thickness to meet traffic demands of each mixture. The design was performed using MeDiNa software. Among all results, it is highlighted that asphalt binder content is the component that exerts the greatest influence on the resilient modulus of the mixtures. As for fatigue, in addition to the binder content, the possible anchoring of the asphalt binder in the pores of the RCA may have favored the performance of the GARC_MRAP mixture. Still, all mixtures with RAP, both in fine or course fraction, resulted in lower coating thicknesses compared to the REF, for the same load request, with better performance of the GARC_MRAP mixture produced with 100 % waste material and incorporation of only 3.1 % neat binder.

EFFECT OF RECYCLED CONCRETE AGGREGATE, AIR ENTRAINING ADMIXTURE AND MAXIMUM AGGREGATE PARTICLE SIZE ON THE BEHAVIOR OF CONCRETE UNDER FREEZE-THAW CYCLES

2021 ◽  
Vol 16 (2) ◽  
pp. 217-233
Author(s):  
Yeşim Tarhan ◽  
Remzi Şahin
Keyword(s):  
Capillary Permeability ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Particle Sizes ◽  
Recycled Concrete Aggregate ◽  
Nacl Solution ◽  
Aggregate Particle ◽  
Freeze Thaw ◽  
Concrete Elements ◽  
Parking Facilities

ABSTRACT This article presents freeze-thaw (F/T) resistance of concrete containing recycled concrete aggregate (RCA). RCA percentages of 15%, 30%, 45%, and 60% were replaced by natural aggregate. Air entraining admixture (AEA) with three different ratios (0.06%, 0.13%, and 0.20%) were used and three different maximum aggregate particle sizes (dmax = 16 mm, 22.4 mm and 31.5 mm) were selected. F/T resistances of the concretes were determined through the measurement of scaling on the surfaces of the samples placed in 3% NaCl solution in pursuance of TS CEN/TS 12390-9. It was observed that the compressive strength of the concretes decreased by 20% on average compared to the control samples with the increase in the amount of RCA. However, it was determined from the experiments that the use of RCA increases the F/T resistances of the concretes as it provides extra voids in the concrete and decreases capillary permeability. Within the limits of this study, dmax = 22.4 mm, RCA = 45% and AEA = 0.13% are recommended as the optimum values for F/T resistance of the concrete. It is also recommended to use RCA in pavement applications including roadways, highways, parking facilities, and other non-structural concrete elements subjected to severe winter conditions.

scholarly journals Physical, Deformation, and Stiffness Properties of Recycled Concrete Aggregate

2021 ◽  
Vol 13 (8) ◽  
pp. 4245
Author(s):  
Katarzyna Gabryś ◽  
Emil Soból ◽  
Wojciech Sas
Keyword(s):  
Recycled Concrete ◽  
Experimental Program ◽  
Concrete Aggregate ◽  
Test Results ◽  
Recycled Concrete Aggregate ◽  
Granulometric Analysis ◽  
Stiffness Properties ◽  
Grain Distribution ◽  
Natural Aggregates ◽  
Critical Reduction

The construction sector is currently struggling with the reuse of waste originating from the demolition and modernization of buildings and roads. Furthermore, old buildings are gradually being replaced by new structures. This brings a significant increase of concrete debris to waste landfills. To prevent this, many studies on the possibilities of recycling concrete, known as recycled concrete aggregate (RCA), have been done. To broaden the applicability of reused concrete, an understanding of its properties and engineering behavior is required. A difficulty in sustainable, proper management of RCA is the shortage of appropriate test results necessary to assess its utility. For this reason, in the present study, the physical, deformation, and stiffness properties of RCA with gravely grain distribution were analyzed carefully in the geotechnical laboratory. To examine the mentioned properties, an extensive experimental program was planned, which included the following studies: granulometric analysis, Proctor and oedometer tests, as well as resonant column tests. The obtained research results show that RCA has lower values of deformation and stiffness parameters than natural aggregates. However, after applying in oedometer apparatus repetitive cycles of loading/unloading/reloading, some significant improvement in the values of the parameters studied was noticed, most likely due to susceptibility to static compaction. Moreover, some critical reduction in the range of linear response of RCA to dynamic loading was observed.

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