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Home > Publications > 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 129 Abstracts search results
May 1, 2021
March 1, 2021
Anvit Gadkar and Kolluru V. L. Subramaniam
Self-leveling concrete is developed with low-calcium alkali-activated fly ash (AAF) binder paste. The rheological behavior of AAF pastes with different compositions is evaluated. AAF pastes are proportioned with alkali-silicate activating solutions to ensure specific reactive oxide ratios for comparable geopolymer strength. The yield stress and the viscosity of the AAF binder paste vary with the silica content and the silica modulus (SiO2/Na2O mass ratio) in the alkali-silicate activating solution. The slump and flow behaviors of concrete mixtures made with AAF paste are evaluated. The requirements of the AAF binder characteristics, paste content, and aggregate packing for achieving self-leveling flow characteristics under gravity-induced flow are assessed. The transition from a frictional to a flow-type behavior in concrete mixtures depends on the AAF binder paste content. Self-leveling is achieved without the use of admixtures with an AAF binder paste of low yield stress and at a paste content of 45%. Improving the aggregate packing using the Fuller-Thompson curve and reducing the yield stress of the AAF
binder paste increase the flow achieved in concrete mixtures. The specifications for cement-based self-consolidating concrete (SCC) are closely applicable for self-leveling AAF-based concrete.
Mohamed M. Sadek and Assem A. A. Hassan
This study evaluated the abrasion resistance for a number of lightweight self-consolidating concrete (LWSCC) incorporating coarse and fine lightweight expanded slate aggregates (LC or LF, respectively). The study also investigated the abrasion resistance before and after exposure to freezing-and-thawing cycles in the presence of deicing salt. The investigated parameters included different volumes of LC and LF aggregates, three binder contents (500, 550, and 600 kg/m3 [31.2, 34.3, and 37.5 lb/ft3]), and different types of concrete (LWSCC, lightweight vibrated concrete, and normal-weight self-consolidating concrete). Increasing the percentage of expanded slate aggregate decreased the abrasion resistance. Mixtures with LF showed higher strength-per-weight ratio and higher abrasion and salt-scaling resistance compared to mixtures with LC. Samples exposed to abrasion before salt scaling had higher mass losses due to salt scaling with an average of 26.8%
compared to non-abraded ones. Higher mass loss was also observed in mixtures exposed to abrasion after the exposure to salt scaling with an average of 26% and 43.3% in the rotating-cutter and sandblasting abrasion tests, respectively.
September 1, 2020
Faez Sayahi, Mats Emborg, Hans Hedlund, and Andrzej Cwirzen
This research studies the effect of retarder, accelerator, stabilizer, air-entraining agent, and shrinkage-reducing admixture (SRA) on plastic shrinkage cracking in self-consolidating concrete (SCC). The main objective is to identify the dominant cracking cause—that is, plastic settlement or plastic shrinkage—in an SCC containing a particular admixture. During experimentation, crack-free concretes were achieved by adding air-entraining agent and SRA, while accelerator and retarder increased the crack area. The impact of admixtures on the cracking mechanism was identified by comparing the respective vertical and horizontal deformations. It was observed that the crack-free concretes had moderate settlement and horizontal shrinkage, while the cracked specimens exhibited significant deformation either vertically or horizontally.
Ahmed T. Omar, Mohamed M. Sadek, and Assem A. A. Hassan
This study aims to evaluate the impact resistance and mechanical properties of a number of developed lightweight self-consolidating concrete (LWSCC) mixtures under cold temperatures. To achieve LWSCC mixtures with minimum possible density, the authors explored different replacement levels of normalweight fine or coarse aggregates by lightweight fine and coarse expanded slate aggregates. The studied parameters included testing temperature (+20°C, 0°C, and –20°C), type of lightweight aggregate (either fine or coarse expanded slate aggregates), binder content (550 and 600 kg/m3 [34.3 and 37.5 lb/ft3]), coarse-to-fine (C/F) aggregate ratio (0.7 and 1.0), and the use of polyvinyl alcohol (PVA) fibers (fibered and nonfibered mixtures). The results indicated that for all tested mixtures, decreasing the temperature of concrete below room temperature significantly improved the mechanical properties and impact resistance. Increasing the percentage of lightweight fine or coarse aggregate in the mixture showed more improvement in the mechanical properties and impact resistance under cold temperatures. However, the failure mode of all tested specimens appeared to be more brittle under subzero temperatures. It was also observed that the inclusion of PVA fibers helped to compensate for the brittleness that resulted from decreasing the temperature, and it further enhanced the impact resistance and mechanical properties under low temperatures.
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