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International Concrete Abstracts Portal

Showing 1-5 of 128 Abstracts search results

Document: 

22-206

Date: 

December 1, 2023

Author(s):

Rita Maria Ghantous, Margaret N. Goodwin, Mehdi Khanzadeh Moradllo, Sean Quinn, Vahit Aktan, O. Burkan Isgor, Steven Reese, and W. Jason Weiss

Publication:

Materials Journal

Volume:

120

Issue:

6

Abstract:

Carbonatable calcium silicate cement (CSC) is a promising approach to reducing the carbon footprint associated with concrete production. Carbonatable CSC gains strength by reacting with carbon dioxide (CO2). While the concept of carbonation is well known, more information on the curing process is needed. This study focuses on studying the impact of drying time, carbonation duration, and degree of saturation (DOS) on the carbonation reaction of CSC mortar. Samples were exposed to different drying durations at controlled environmental conditions to reach various DOSs ranging from 100 to 0%. The samples were then exposed to carbonation under the same environmental conditions for different durations. Neutron radiography (NR) was performed on the samples during drying to determine the DOS corresponding to various drying durations. NR was also used during the carbonation period to determine the degree of carbonation (DOC) in real time. The impact of carbonation on the diffusivity of water vapor (Dh) and pore size distribution of CSC-based samples was examined using dynamic vapor sorption (DVS). It was concluded that the carbonation reaction increased as the DOS decreased from 100 to 40%. The carbonation reaction ceased for samples with DOS values less than 6% DOS. It was also concluded that as the DOC increased, the pore structure was refined, which led to a decrease in the Dh of the CSC mortar samples.

DOI:

10.14359/51739146


Document: 

22-217

Date: 

November 14, 2023

Author(s):

Amin K. Akhnoukh, Mathew Campbell

Publication:

Materials Journal

Abstract:

The U.S. National Oceanographic Services estimates 154,080 km (95,741 miles) of shorelines in the United States, where 163 miles/year are hardened by bulkheads and riprap. These shoreline protection techniques are costly and require frequent maintenance. Different agencies are examining “nature-based” solutions that combine vegetation with traditional concrete. Digital construction, advanced manufacturing, and innovative cementitious composites have additionally been proposed as potential means to lower material usage, cost, and environmental impact. This paper presents a novel advanced manufacturing technique using a reactive-diffusion morphological process, called “Dry FormingTM”, to 3-D print concrete structures of various shapes, sizes, and complexity with standard concrete mixes. This technology has reduced 60% of the material use; enhances local habitats, and increases the resiliency of the shoreline to sea level rise. The widespread of this technology would increase the resiliency in coastal communities, protect aquatic life, and protect waterfront public and private real estate investments.

DOI:

10.14359/51740264


Document: 

22-124

Date: 

September 1, 2023

Author(s):

Arindam Dey, Tara L. Cavalline, Miras Mamirov, and Jiong Hu

Publication:

Materials Journal

Volume:

120

Issue:

5

Abstract:

The use of recycled concrete aggregates (RCAs) in lieu of natural aggregates improves the sustainability of the built environment. Barriers to the use of RCA include its variable composition, including the residual mortar content (RMC), chemical composition, and its potential to contain contaminants, which can negatively affect the properties of concrete or present environmental concerns. In this study, a rapid, economical method to estimate the RMC and provide the chemical characterization of RCA was developed using a portable handheld X-ray fluorescence (PHXRF) device. Models were developed using reference tests (RMC test based on the thermal shock method and chemical composition from whole-rock analysis) to correlate PHXRF results to measured values. The PHXRF shows strong potential for estimating the RMC and chemical composition of RCA. Paired with locally calibrated reference samples, the test method could be used in laboratory or field applications to characterize RCA and increase its use in bound and unbound applications.

DOI:

10.14359/51738890


Document: 

21-483

Date: 

September 1, 2023

Author(s):

Nima Mohammadian Tabrizi, Davood Mostofinejad, and Mohammad Reza Eftekhar

Publication:

Materials Journal

Volume:

120

Issue:

5

Abstract:

This paper is aimed at investigating the effects of different fiber inclusion on the mechanical properties of ultra-high-performance concrete (UHPC) by adding mineral admixtures as cement replacement materials to reduce production costs and CO2 emissions of UHPC. Throughout this research, 21 mixture designs containing four cement substitution materials (silica fume, slag cement, limestone powder, and quartz powder) and three fibers (steel, synthetic macrofibers, and polypropylene) under wet and combined (autoclave, oven, and water) curing were developed. To investigate the mechanical properties in this research, a total of 336 specimens were cast to evaluate compressive strength, the modulus of rupture (MOR), and the toughness index. The findings revealed that at the combined curing, regarded as a new procedure, all levels of cement replacement recorded a compressive strength higher than 150 MPa (21.76 ksi). Furthermore, the mechanical properties of the mixture design containing microsilica and slag (up to 15%) were found to be higher than other cement substitutes. Also, it was shown that all levels of the fiber presented the MOR significantly close together, and samples made of synthetic macrofibers and steel fibers exhibited deflection-hardening behavior after cracking. The mixture design containing microsilica, slag, limestone powder, and quartzpowder, despite the significant replacement of cement (approximately 50%) by substitution materials, experienced a slight drop in strength. Therefore, the development of this mixture is optimal both economically and environmentally.

DOI:

10.14359/51738888


Document: 

22-222

Date: 

July 1, 2023

Author(s):

Saida Kitouni

Publication:

Materials Journal

Volume:

120

Issue:

4

Abstract:

The aim of this study was to determine the effect of different amounts of filler on concrete properties. An experimental approach has made it possible to develop a construction product made from limestone dust, which is considered waste. This paper presents an experimental study on the prospects of using a mixture of waste limestone powder for the manufacture of an economical and lightweight composite as a building material. This paper also presents the results of research on the possibility of using limestone dust as an aggregate in the production of concrete with lightweight aggregates. In this way, different amounts of limestone dust were used. Tests were conducted on concrete to replace 30, 50, and 70% by weight of coarse aggregate. The mechanical properties of concrete mixtures with high proportions of limestone dust were examined. The achieved compressive strength, flexural strength, and unit weight correspond to current international standards.

DOI:

10.14359/51738807


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