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International Concrete Abstracts Portal

Showing 1-5 of 139 Abstracts search results

Document: 

22-192

Date: 

July 1, 2023

Author(s):

Omar A. Kamel, Ahmed A. Abouhussien, Assem A. A. Hassan, and Basem H. AbdelAleem

Publication:

Materials Journal

Volume:

120

Issue:

4

Abstract:

This study investigated using acoustic emission (AE) monitoring to assess the abrasion performance of fiber-reinforced selfconsolidating concrete at cold temperatures (–20°C). In addition, the study targeted correlating the abrasion damage to AE data through AE intensity analysis parameters. Seven concrete mixtures were developed with variable water-binder ratios (w/b) (0.4 and 0.55), fiber types (steel and polypropylene synthetic fibers), fiber lengths (19 and 38 mm), and fiber volumes (0.2 and 1%). Tests on 100 mm cubic samples were conducted at –20 and 25°C, for comparison, according to the rotating-cutter technique in conjunction with AE monitoring. Characteristics of the AE signals such as signal amplitudes, number of hits, and signal strength were collected and underwent b-value and intensity analyses, resulting in three subsidiary parameters: b-value, severity (Sr), and the historic index (H(t)). A clear correlation between abrasion damage progress and AE parameters was noticed. Analyzing AE parameters along with experimental measurements generally revealed a better abrasion resistance for all mixtures when tested at –20°C compared to those at room temperature. The mixtures with steel fibers, lower w/b values, shorter fibers, and higher fiber volume showed improved abrasion resistance irrespective of temperature. Noticeably, the mixtures containing longer fibers, higher w/b values, or lower fiber dosages experienced a more pronounced enhancement ratio in the abrasion resistance when cooled down to sub-zero temperatures. Two damage classification charts were developed to infer the mass loss percentage and wear depth due to abrasion using intensity analysis parameters: Sr and H(t).

DOI:

10.14359/51738806


Document: 

21-466

Date: 

January 1, 2023

Author(s):

Xiaoguang Chen, Zeger Sierens, Elke Gruyaert, and Jiabin Li

Publication:

Materials Journal

Volume:

120

Issue:

1

Abstract:

Mixed recycled aggregate (MRA) is considered a sustainable construction material, and its use in precast concrete is currently banned due to its poor engineering performance. This paper aims to evaluate the feasibility of partial replacement of natural coarse aggregate with MRA in self-consolidating concrete (SCC) for manufacturing architectural precast concrete sandwich wall panels. To this end, five MRAs from recycling plants were characterized, out of which two were selected to develop SCC. SCC mixtures with three replacement levels and three water compensation degrees were produced, and their physical, mechanical, durability, and aesthetic properties were examined. The results showed that the incorporation of MRA dominated the mechanical properties of SCC, while the water compensation degree primarily affected the flowability and carbonation resistance. The presence of MRA had no considerable effect on the aesthetic characteristics. Up to 10% MRA in weight of total aggregates could be used in precast SCC.

DOI:

10.14359/51737333


Document: 

21-364

Date: 

November 1, 2022

Author(s):

A. F. Angelin, E. J. P. de Miranda Junior, J. M. C. dos Santos, W. R. Osório, R. C. Cecche Lintz, and L. A. Gachet

Publication:

Materials Journal

Volume:

119

Issue:

6

Abstract:

Self-consolidating concretes (SCCs) have been widely studied in recent years. However, investigations concerning self-consolidating lightweight rubberized concrete (SCLRC) are scarce. This paper focuses on both the expanded clay and waste tire rubber contents. Both the fresh and hardened properties are evaluated. Additionally, the thermal and acoustic properties are also analyzed. Because the expanded clay has a rounded shape without edges or tips, presenting a smooth and glassy surface, it improves the workability and spreading of the concrete. Also, the mechanical behavior, together with the lightweight effect and associated with thermal conductivity, is a remarkable property attained. The rubber acts negatively on the properties in the fresh state of SCLRC. The compressive strength of SCLRC is lower than that of conventional SCC. It is found that with the use of light aggregates, which are replaced with conventional aggregates, an increase of approximately 50% in the acoustic attenuation and a decrease of 70% in the thermal conductivity are attained. This induces better thermal and acoustic insulation than the conventional concrete associated with being environmentally friendly.

DOI:

10.14359/51736005


Document: 

21-099

Date: 

September 1, 2022

Author(s):

Mohammed A. Abed, Mohammad Alrefai, Asaad Alali, Rita Nemes, and Sherif Yehia

Publication:

Materials Journal

Volume:

119

Issue:

5

Abstract:

Nominal maximum aggregate size (MAS) and particle distribution affect the performance of concrete significantly. However, their effect is influenced by the type of aggregate and the target concrete strength. This research investigates the effect of MAS on the mechanical performance of high-strength self-consolidating concrete (HSSCC). Two different types of coarse aggregates, natural quartz aggregate (NA) and recycled concrete aggregate (RA), were used in the evaluation. Compressive, splitting tensile, flexural, and shear strengths were tested and used as criteria for evaluation. Ultrasonic pulse velocity and rebound value were also used as nondestructive evaluation techniques. The results showed that compressive strength decreased when using a bigger MAS of NA, while it increased when using a bigger MAS of RA. However, this conclusion cannot be generalized to include all mechanical properties of concrete, as the failure mechanism for each test depends on the type and size of aggregate. In addition, finite and discrete element methods were applied to study the effect of MAS as well as to simulate the experimental performance of concrete. Following proper proportioning and mixing, RA could be used to produce HSSCC concrete.

DOI:

10.14359/51735948


Document: 

21-106

Date: 

March 1, 2022

Author(s):

Ahmed T. Omar and Assem A. A. Hassan

Publication:

Materials Journal

Volume:

119

Issue:

2

Abstract:

This paper investigates the structural performance of large-scale lightweight self-consolidating concrete (LWSCC) and lightweight vibrated concrete (LWVC) beams made with expanded slate coarse aggregates (ESCAs) and expanded slate fine aggregates (ESFAs) under flexural loads. Nine large-scale concrete beams were cast with different types of lightweight aggregate (either ESCA or ESFA), coarse-to-fine aggregate ratios (0.5 to 1.5), and total binder contents (550 and 600 kg/m3 [34.3 and 37.5 lb/ft3]). The structural performance of the tested beams was assessed based on the characteristics of the load-deflection response, cracking pattern, displacement ductility, energy absorption, cracking moment, and ultimate flexural strength. The reliability of code-based expressions in predicting the cracking and ultimate moment capacity of the tested beams was also investigated in this study. The results indicated that using ESFA better improved the beam’s cracking moment capacity, deformability, ductility, and energy absorption capacity compared to using ESCA. Although LWSCC exhibited a lower modulus of elasticity than normal-weight SCC, the deflection values observed in the LWSCC beams under service loads were well within the allowable limit provided by BS 8110. The measured crack widths at the service loads for all tested beams ranged from 0.20 to 0.26 mm (0.008 to 0.01 in.), satisfying the limits proposed by ACI 318, CSA A23.3, and BS 8110 design codes for durability aspects.

DOI:

10.14359/51734200


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