International Concrete Abstracts Portal

Showing 1-5 of 583 Abstracts search results

Document: 

23-329

Date: 

December 1, 2024

Author(s):

S. Al-Fadala, D. Dashti, H. Al-Baghli, J. Chakkamalayath, and Z. Awadh

Publication:

Materials Journal

Volume:

121

Issue:

6

Abstract:

Compared to external curing, internal curing enables the judicious use of available water to provide additional moisture in concrete for more effective hydration and improvement in the performance of concrete structures. However, certain challenges with the incorporation of internal curing materials (ICMs) still need to be addressed, as their effectiveness depends on several factors. Furthermore, sustainable construction demands the use of recycled materials, and this paper discusses the comparative evaluation of recycled aggregate (RA) as an ICM, along with two other types of ICMs, on various properties of high-performance concrete in the hardened state under two curing conditions. Concrete mixtures were prepared with pre-wetted RAs, superabsorbent polymers (SAPs), and pre-wetted lightweight volcanic aggregates (LWVAs) as ICMs. Concrete performance was compared through the investigation of the strength development, shrinkage, mass loss, and volumetric water absorption. In addition, the change in internal humidity of concrete with time at different stages of hardening was determined. The compressive strength results showed that RA and LWVA are more efficient in early days, and the performance of SAP is better in the later age due to its slow water releasing capabilities. Compared to the control mixture, the least reduction in strength of 4% and 8% at 28 days and 90 days, respectively, could be observed for the mixtures containing RA under both air and water curing.

DOI:

10.14359/51742261


Document: 

23-288

Date: 

August 1, 2024

Author(s):

Deep Tripathi, Richard Morin, Mohamed Lamine Kateb, and Arezki Tagnit-Hamou

Publication:

Materials Journal

Volume:

121

Issue:

4

Abstract:

Ground-glass pozzolan has recently been considered a supplementary cementitious material by Canadian (CSA A3000) and American (ASTM C1866/C1866M) standards, but limited studies have been done on ground-glass use on-site. So, in this study, several sidewalk projects were performed by the SAQ Industrial Chair at the University of Sherbrooke from 2014 to 2017 on fields with different proportions of ground glass (that is, 10, 15, and 20%) in different conditions considered in such a cold climatic region. Sidewalks are a nonstructural plain concrete element that are among the most exposed to chloride and freezing and thawing in saturated conditions of municipal infrastructures. Coring campaigns were carried out on these concretes after several years of exposure (between 5 and 8 years). The results of core samples extracted from the sites were compared to the laboratory-cured samples taken during the casting. These laboratory concrete mixtures were tested for fresh, hardened (compressive strength), and durability (freezing and thawing, scaling resistance, chloride-ion penetrability, electrical resistivity, and drying shrinkage) properties (up to 1 year). The results show that ground-glass concrete performs very well at all cement replacements in all manners in terms of long-term performance. Besides that, using ground-glass pozzolan in field projects also decreases the carbon footprint and environmental and glass disposal problems.

DOI:

10.14359/51740781


Document: 

23-244

Date: 

August 1, 2024

Author(s):

Jamin Park, Oh-Sung Kwon, and Evan C. Bentz

Publication:

Materials Journal

Volume:

121

Issue:

4

Abstract:

Though extensive experimental studies have been conducted for shrinkage, studies focusing on shrinkage of high volume-to surface ratio (V/S) concrete in low-relative-humidity conditions are relatively scarce. Accordingly, most shrinkage prediction models are applicable for relatively medium- to high-humidity conditions with a V/S of 100 mm (3.9 in.) or less. In this study, to evaluate the prediction accuracy of current shrinkage prediction models for conditions with high V/S and low-relative-humidity conditions, long-term measurements of shrinkage were conducted with 28 rectangular prism-shaped concrete specimens 76.2 x 76.2 x 285 mm (3.0 x 3.0 x 11.2 in.) or 125 x 125 x 550 mm (4.9 x 4.9 x 21.7 in.) in size with V/S ranging from 16.8 to 285 mm (0.7 to 11.2 in.). The results reveal that current shrinkage prediction models, such as the ACI 209R-92, fib Model Code 2010 (MC2010), B3, and GL2000 models, can significantly underestimate the long-term shrinkage in relative humidity less than 20%, depending on the V/S. The prediction accuracy of the ACI 209R-92 and fib MC2010 models depends on how model parameters on the member’s geometry, such as the V/S, are determined.

DOI:

10.14359/51740779


Document: 

23-267

Date: 

July 1, 2024

Author(s):

Shui Liu, Xin Wang, Yahia M. S. Ali, Huang Huang, and Zhishen Wu

Publication:

Structural Journal

Volume:

121

Issue:

4

Abstract:

This study presents a critical evaluation of the deflection calculation for hybrid-reinforced concrete (hybrid-RC) with fiber-reinforced polymer (FRP) and steel bars by employing existing expressions for the effective moment of inertia Ie. A new rational and simple approach is proposed to account for concrete shrinkage restraint caused by both steel and FRP bars and modify the existing reduction factors in the expressions from ACI 318-19 and ACI CODE- 440.11-22. The calculated deflections by the modified expressions, as well as Branson’s equation and the method specified in CSA S806-12, are compared with the experimental values from a database including 119 hybrid-RC members. The comparisons indicate that the modified expression from ACI 318-19 provides the most accurate deflection predictions. Moreover, the modified expression from ACI CODE-440.11-22, which further includes the consideration of varied stiffness along the member span, proves to be particularly effective for cases with relatively lower reinforcement ratios.

DOI:

10.14359/51740717


Document: 

23-274

Date: 

July 1, 2024

Author(s):

Koshiro Nishimura and Sujan Pradhan

Publication:

Structural Journal

Volume:

121

Issue:

4

Abstract:

In this study, five reinforced concrete (RC) beam specimens with transverse web openings and one specimen without openings were prepared. Diagonal steel bars were arranged around the web openings in the beam specimens so as not to fail at the section with the openings. The specimens were subjected to static reversed-cyclic shear loading of double curvature, and those specimens failed in shear at a different part than the section with the web openings. This paper provides a simple model of the relationship between stress in the diagonal reinforcement around the openings and the applied shear load considering the shrinkage of concrete. Moreover, an evaluation method of the ultimate shear capacity of the beam using the upper-bound solution of the limit analysis was also provided. These models showed good agreement with the test results. The study contributes to the crack control and safety of RC beams with openings.

DOI:

10.14359/51740576


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