International Concrete Abstracts Portal

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.

Showing 1-5 of 31692 Abstracts search results

Document: 

24-335

Date: 

July 10, 2025

Author(s):

Feyza Nur Sahan, W. Jason Weiss, O. Burkan Isgor

Publication:

Materials Journal

Abstract:

The role of limestone (LS) powder replacement and changes in C-S-H due to pozzolanic reactions on the acid resistance of cementitious pastes are studied using thermodynamic modeling. Simulations are performed under equilibrium conditions while hydration products were exposed to increasing levels of sulfuric acid. LS replacement doesn’t show sacrificial characteristics against sulfuric acid attack, and LS acidification starts only after full consumption of portlandite, and most C-S-H. Increased LS replacement causes the dilution of the formed portlandite and C-S-H volumes, which results in their full consumption at lower acid concentrations than mixtures without LS replacement. Pozzolanic reactions of SCMs result in C-S-H phases with lower Ca/Si than OPC-only counterparts, increasing acid resistance. However, highly reactive and/or high-volume SCM replacements might further decrease the available portlandite, reducing the buffer acid resistance capacity. This issue is particularly critical for portland limestone cement-based systems.

DOI:

10.14359/51749035


Document: 

24-434

Date: 

July 10, 2025

Author(s):

Justin Dickey, Kevin J. Folliard, Thanos Drimalas

Publication:

Materials Journal

DOI:

10.14359/51749036


Document: 

24-030

Date: 

July 1, 2025

Author(s):

Kwanwoo Yi and Thomas H.-K. Kang

Publication:

Structural Journal

Volume:

122

Issue:

4

Abstract:

This study used finite element analysis to examine how tendon configuration affects the temperature behavior of post-tensioned concrete structures during fire exposure. The thermal behavior of various tendon configurations was modeled, showing good agreement with experimental data. Parametric studies found that unbonded single-strand tendons (S) and prestressing (pretensioned) strands (R) had lower thermal resistance than bonded post-tensioned tendons (B), unbonded post-tensioned tendons (U), and grouted extruded-strand tendons (G). The S and R specimens stayed at or below the critical temperature for one-way slabs, validating current safety codes. The B, U, and G specimens remained well below critical temperatures, indicating that a thinner concrete cover might suffice. These findings highlight the need to consider tendon configuration in structural fire-resistance evaluation and incorporate heat resistance assessment to ensure the safety and efficiency of prestressed concrete structures during fires.

DOI:

10.14359/51745642


Document: 

23-264

Date: 

July 1, 2025

Author(s):

M.-Y. Cheng, P.-J. Chen, C.-H. Chen, B. L. Worsfold, G. J. Parra-Montesinos, and J. P. Moehle

Publication:

Structural Journal

Volume:

122

Issue:

4

Abstract:

Recent tests showed that anchorage failure could be the primary mechanism that limits the strength and deformation capacity of column-footing connections. An experimental program consisting of the reversed cyclic load testing of 16 approximately full-scale column-footing subassemblages was thus conducted to investigate the effect of various reinforcement details on connection strength, drift capacity, and failure mode. The main parameters evaluated were type of anchorage for the column longitudinal bars (either hooks or heads), extension of column transverse reinforcement into the footing, and longitudinal and transverse reinforcement ratios in the footing. Test results indicate that even when column longitudinal reinforcement extends into the joint with a development length in accordance with ACI 318-19, a cone-shaped concrete breakout failure may occur, limiting connection strength and deformation capacity. The use of transverse reinforcement in the connection over a region extending up to one footing effective depth away from each column face proved effective in preventing a concrete breakout failure. However, for the specimens with column headed bars, extensive concrete crushing adjacent to the bearing side of the heads and spalling beyond the back side of the heads led to significant bar slip and “pinching” in the load versus drift hysteresis loops at drift ratios greater than 3%. The use of U-shaped bars in the joint between the column and the footing or slab, as recommended in ACI 352R-02, led to improved behavior in terms of strength and deformation capacity, although it did not prevent the propagation of a cone-shaped failure surface outside the joint region. Based on the test results, the basic concrete breakout strength, Nb, corresponding to a 50% fractile, in combination with a cracking factor ψc,N = 1.25, is recommended when using Section 17.6.2. of ACI 318-19 for calculation of concrete breakout strength in connections similar to those tested in this investigation.

DOI:

10.14359/51746671


Document: 

24-029

Date: 

July 1, 2025

Author(s):

S. Ali Dadvar, S. Mousa, H. M. Mohamed, A. Yahia, and B. Benmokrane

Publication:

Structural Journal

Volume:

122

Issue:

4

DOI:

10.14359/51746672


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