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 2529 Abstracts search results

Document: 

SP-362_27

Date: 

June 11, 2024

Author(s):

Shizhe Zhang, Jeroen Lenderink, Marc Brito van Zijl, Vincent Twigt, Rob Bleijerveld

Publication:

Symposium Papers

Volume:

362

Abstract:

The shortage of high-quality fine aggregate as an essential component of concrete has become an emerging worldwide concern for the construction industry. Concrete typically comprises up to 30% fine aggregate, which largely influences the strength and durability of the final product. Therefore, finding suitable substitutes for natural fine aggregate has become an important aspect of current concrete research.

In this study, we investigated the suitability of using remediated thermal-treated soil and tar-containing asphalt as secondary raw materials in a self-compacting concrete (SCC) mixture. The remediated materials were used as both (1) fine aggregate replacement to replace all the river sand and (2) partial filler/supplementary cementitious material (SCM) replacement. The modified Andreasen and Andersen (A&A) particle packing model was used to determine the optimal replacement level. Based on the optimal mixture design, the impact of the replacement on the fresh and mechanical properties of SCC was evaluated. Additionally, the pozzolanic reactivity of the fine fraction (<125 μm) within the secondary sand was assessed and compared to that of limestone powder. Our findings confirm that using remediated thermal-treated soil and tar-containing asphalt can produce a more circular, sustainable SCC by replacing high-quality natural sand and limestone filler and reducing the environmental impact of conventional SCC. This study contributes to finding viable alternatives to natural fine aggregate and promotes the use of recycled materials in construction.


Document: 

SP-362_23

Date: 

June 6, 2024

Author(s):

Ameer Hamza Ahmed, Marco Liebscher, Cesare Signorini and Viktor Mechtcherine

Publication:

Symposium Papers

Volume:

362

Abstract:

This study focuses on the feasibility of replacing fly ash with limestone and calcined clay in strain-hardening cementitious composites (SHCC). Three types of composites were considered: a reference one containing fly ash and the other containing two distinct calcined clays (moderate and high metakaolin content) as supplementary cementitious materials (SCM). Mixtures utilized portland cement (PC) with clinker factors of 0.4 and 0.3, reinforced with 2 vol.% high-density polyethylene (HDPE) fibers. At first, the R3 bound water test was carried out to explicitly assess the reactivity of fly ash and the two calcined clays. Subsequently, the compressive and direct tensile behavior of the SHCCs after 28 days of curing age was evaluated. The results revealed that the SHCCs incorporating calcined clays outperformed their counterpart in terms of compressive strength, tensile strength, and ultimate strain, owing to their high pozzolanic activities, and physical properties, particularly their distinct morphologies. Crack analysis conducted through digital image correlation (DIC) highlighted that the SHCCs with calcined clays established a stronger fiber/matrix interface. In conclusion, this research provides valuable insights into the design of ductile SHCC with novel limestone calcined clay cement (LC3), for enhanced sustainability and cost-effectiveness.


Document: 

SP-362_13

Date: 

June 5, 2024

Author(s):

Barbara Aboagye, Ryan Gosselin, William Wilson

Publication:

Symposium Papers

Volume:

362

Abstract:

As the worldwide availability of natural sand for concrete continues to decline, attention has turned to manufactured sand obtained from coarse aggregates as an alternative. However, there is still limited information regarding its use in concrete mixtures beyond adhering to standard particle gradation bounds (e.g., CSA A23.1 bounds in Canada). To address the gap, this study presents a central composite design of experiments to analyze the influence of mix proportions on the packing density of concrete mixtures incorporating four types of aggregates: 2 mm sand and manufactured sand, 5-14 mm and 10-20 mm coarse aggregates. The packing density was measured using an intensive compaction tester and results were analyzed using a response surface methodology. The study also included four optimized mix designs obtained using the Fuller-Thompson and the Funk and Dinger methods. Results indicate that a higher proportion of manufactured sand and a higher packing density can be achieved with a particle gradation having a higher proportion of smaller-sized particles. Moreover, the TFA/TA (total fine aggregates/total aggregates) ratio significantly influenced the packing density, whereas the impact of the ratio of 5–14 mm/total coarse aggregates (TCA) was minimal. A prediction model for packing density was developed using multiple regression analysis. These findings provide information on how manufactured sand affects the packing density, which can serve as a foundation for designing concrete mixtures with manufactured sand.


Document: 

SP-362_14

Date: 

June 5, 2024

Author(s):

Boulkhiout M., Benna Y., Bali A., Benyoussef E.H., Silhadi K.

Publication:

Symposium Papers

Volume:

362

Abstract:

This work investigates the influence of partial substitution of sand, which is becoming scarce, by the fines-rich limestone tuff sand on the fresh and mechanical performances of self-compacting concrete (SCC). A full three-factor design was applied to demonstrate the individual and combined effects of cement dosage, tuff substitution rate, and superplasticizer dosage on the spread, sieve stability and L-box fill rate, and compressive strength of the different formulated SCC. The SCCs were formulated with Algerian Htattba tuff containing 34% fines, at substitution percentages ranging from 35 to 55%. The limestone tuff sand proved to be well suited for use in the formulation of the SCCs, which are expected to perform well in the fresh state. The use of limestone tuff sand at high substitution rates resulted in a fluid, stable SCC that flowed perfectly through the iron bars of the Lbox without blockage and complied with the recommendations of the French Association of Civil Engineering, AFGC. The main influences observed after analysis of the responses obtained highlighted the predominant effect of the superplasticizer followed by the non-negligible positive effect of the limestone tuff, on the fresh characteristics of the formulated SCC. The first results show that the introduction of limestone tuff up to a substitution rate of 55% gives a consequent workability of 690 mm and a good compressive strength of about 40 MPa. It should be noted that a 55% substitution rate presents an undeniable economic and environmental interest by reducing the quantity of sand considered a "noble material" which is less and less available.


Document: 

SP-362_01

Date: 

June 5, 2024

Author(s):

Wu and Jishen Qiu

Publication:

Symposium Papers

Volume:

362

Abstract:

Reactive magnesia cement (RMC) is an emerging class of low-alkaline and CO2-sequestering binder, which can mitigate the deterioration of GFRP reinforcements induced by a high alkaline environment, e.g., in Portland cement. This study investigated the slip behavior of GFRP rebar embedded in RMC composite, which varies with carbonation depth significantly. The variation of the interfacial bond was determined by a specially designed push-out test of the GFRP core; the variation of the carbonation degree and microstructure was examined by SEM-EDX, XRD, TGA, and acid digestion tests. Both properties demonstrated a similar trend, decreasing rapidly with increasing depth. A new finite element model that considers the depth-dependency of the matrix compositions and the rebar-to-matrix interfacial bond is established. It can predict the constitutive bond-slip behavior of a long GFRP rebar embedded in an RMC composite with non-uniform carbonation.


12345...>>

Results Per Page