ABOUT THE INTERNATIONAL CONCRETE ABSTRACTS PORTAL

  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal

Showing 1-5 of 138 Abstracts search results

Document: 

22-260

Date: 

January 1, 2024

Author(s):

Amit Kumar, Gyani Jail Singh, Priyanshu Raj, and Rajesh Kumar

Publication:

Materials Journal

Volume:

121

Issue:

1

Abstract:

This research examines the performance of quality-controlled recycled concrete aggregates (QRAs) with fly-ash-based cement. Compared to concrete made from untreated recycled concrete aggregates (URC), quality-controlled recycled aggregate concrete (QRC) has superior physical, mechanical, and durability properties. Except for sorptivity, the physical, mechanical, and durability properties of QRC are almost identical to those of natural aggregate concrete (NC). The compressive strength, splitting tensile strength, flexural strength, fracture energy, and modulus of elasticity of QRC are higher than those of URC by 18.0%, 16.8%, 60.0%, 27.17%, and 43.46%, respectively. The abrasion resistance of QRC is approximately 60% higher than URC. Scanning electron microscope (SEM) image and energy-dispersive X-ray (EDX) analysis prove that quality control produces denser old interfacial transition zones (OITZ) with fewer microvoids. The QRA improves not only the pore structure but also the weak mortar structure attached to the aggregate. There is also a strong correlation between the compressive strength and splitting tensile strength, flexural strength, fracture energy, and modulus of elasticity of QRC. QRA can be used to compute the mixture proportions for concrete (certainly up to medium-strength concrete) according to either the Indian standard or the international standard. It is challenging to improve the sorptivity of recycled concrete aggregates closer to NC. In addition, QRC has an initial sorptivity of two times (initial) and a final sorptivity of 1.8 times higher than NC, whereas URC has an initial sorptivity of 3.5 times (initial) and a final sorptivity of 2.35 times higher than NC.

DOI:

10.14359/51740259


Document: 

22-286

Date: 

December 12, 2023

Author(s):

K. Sriram Kompella, Andrea Marcucci, Francesco Lo Monte, Marinella Levi, Liberato Ferrara

Publication:

Materials Journal

Abstract:

The early age material parameters of 3D printable concrete defined under the umbrella of Printability, namely pumpability, extrudability, buildability, and the “printability window/open time” are subjective measures. The need to correlate and successively substitute these subjective measures with objective and accepted material properties such as tensile strength, shear strength, and compressive strength, is paramount. This study validates new testing methodologies to quantify the tensile and shear strengths of printable fiber-reinforced concretes still in their fresh state. A tailored mix, with high sulfo-aluminate cement and non-structural basalt fibers has been assumed as a reference. The relation between the above-mentioned parameters with rheological parameters such as yield strength obtained through ICAR rheometer tests is also explored. Furthermore, in an attempt to pave the way and contribute towards a better understanding of the mechanical properties of 3Dprinted concrete, as to be further transferred into design procedures, a comparative study analyzing the work of fracture per unit crack-width in 3-point bending has been performed on printed and companion nominally identical monolithically cast specimens, investigating the effects of printing directions, position in the printed circuit and specimen slenderness (length to depth) ratio.

DOI:

10.14359/51740302


Document: 

22-139

Date: 

March 1, 2023

Author(s):

Victor Calderon, Moe Pourghaz, and Mervyn Kowalsky

Publication:

Materials Journal

Volume:

120

Issue:

2

Abstract:

Corrosion of reinforcing steel increases the probability of the fracturing of longitudinal reinforcing bars and leads to the loss of load-carrying capacity in reinforced concrete (RC) members. Twenty-four reinforcing steel bars were subjected to the buckled bar tension (BBT) test, and the critical bending strain was obtained at different corrosion levels. The specimens were passivated reinforcing steel bars that were corroded through accelerated electrolytic corrosion. The results show that the critical bending strain decreases as the corrosion level increases. The critical bending strain influences the post-buckling bar fracture limit state and reduces the displacement capacity of columns as the corrosion level in the longitudinal reinforcing bar increases. In addition, the degradation of yield strength, ultimate strength, and uniform axial elongation for corroded reinforcing steel bars were observed.

DOI:

10.14359/51738461


Document: 

21-331

Date: 

September 1, 2022

Author(s):

Vadim Potapov, Yuriy Efimenko, Roman Fediuk, and Denis Gorev

Publication:

Materials Journal

Volume:

119

Issue:

5

Abstract:

Cement concretes modified with hydrothermal nanosilica and basalt microfiber were developed. The compressive strength Fcom, flexural strength Fflex, and characteristics of impact viscosity were determined: the number of blows before the first fracture Nff and before ultimate failure Ncd, the coefficient Niv = Ncd/Nff, and the specific energy of impact destruction Eim/Sc. The strong effect of SiO2 action and synergistic effect of the combined action of nanoparticles and microfiber on Ncd and Eim/Sc was revealed. Statistical correlations with high R2 values were obtained between the characteristics of mechanical strength and impact viscosity at different doses of SiO2 nanoparticles. Correlations obtained can be used for reduction of the cross section of concrete structures and cement consumption. The mechanism of the strong synergistic effect of the combination is explained by the enlargement of the volume fraction of the high-density (HD) phase of calcium-silicate-hydrate (C-S-H) gel with more packed nanogranules and an increase in the shear stress of C-S-H gel relative to the lateral microfiber surfaces inside the HD-phase volume. The reduction of the coefficient of water filtration Kf and an increase in the frost resistance were achieved.

DOI:

10.14359/51735952


Document: 

20-517

Date: 

January 1, 2022

Author(s):

Muhammad N. S. Hadi, Umer Sajjad, and M. Neaz Sheikh

Publication:

Materials Journal

Volume:

119

Issue:

1

Abstract:

Various test methods and techniques are used to determine the shear strength of concrete. However, the available test methods and techniques used for determining the shear strength of concrete are prone to several inconsistencies and limitations, which cause inaccuracies in measuring the shear strength of concrete. A simple test method is proposed in this paper to achieve an accurate measurement of the shear strength of concrete. The proposed method was applied to two groups of concrete representing normal-strength concrete and high-strength concrete. The specimens failed at locations where the area was reduced, providing an accurate estimate of the shear strength of concrete.

DOI:

10.14359/51732986


12345...>>

Results Per Page