International Concrete Abstracts Portal

Carbon dioxide emissions from cement production pose major environmental concerns. This study investigates the combined incorporation of glass powder (GP) as a partial cement replacement and dog hair (DH) as a natural fiber reinforcement in cement paste. GP was incorporated with replacement levels of 5%, 10%, and 15%, whereas DH was incorporated with dosages of 0.25% and 0.5% by weight of cement. Both fresh and hardened properties were evaluated for a duration of up to 90 days. GP enhanced workability, increasing mini-slump by approximately 21% at 15% GP, whereas DH with 0.25% reduced workability by up to 6%. At 90 days, compressive strength improved by 26.6%, 17.6%, and 16.5% for GP5, GP10, and GP15, respectively. Flexural strength was improved by a maximum of 8.9% with the addition of DH. The porosity of all the modified mixes was reduced to a minimum of 20.4% in the GP15-0.25DH mix compared to the control mix of 28.0%. Sustainability analysis showed CO₂ emission reductions ranging from 4.06% to 16.07%, and material cost decreased to a maximum of 15.95% for GP15. These results clearly show the potential of GP and DH to enhance performance while improving economic and environmental sustainability.

This presentation discusses the behavior of a truss bridge under wind loading. To examine the wind-related responses of the bridge, state-of-the-art and traditional modeling methodologies are employed: a machine learning approach called random forest and three-dimensional finite element analysis. Upon training and validating these modeling methods using experimental data collected from the field, member-level forces and stresses are predicted in tandem with wind speeds inferred by Weibull distributions. The intensities of the in-situ wind are dominated by the location of sampling, and the degree of partial fixities at the supports of the truss system is found to be insignificant.

Repeated vehicle loading causes a decrease in transverse joint stiffness in concrete pavements due to damage accumulation around dowel bars. The relationship between key design parameters and damage accumulation is not well established due to limited faulting performance data and a lack of experimental data from expensive full-slab testing. A novel laboratory test setup was developed to characterize damage development caused by repeated vehicle loads. This setup was used to characterize damage for a range of key parameters at a lower cost and level of effort compared to full-scale slab testing. The concept of beam deflection energy, DE_Beam, is also introduced. Experimental results were used to develop a DE_Beam prediction model. The novel test setup developed in this study enables the rapid evaluation of a variety of dowel materials and geometries, and experimental results can be used to improve current faulting prediction performance.

Slender reinforced concrete columns have been employed as components of telecommunication and internet infrastructure since the deployment of the system more than 30 years ago. The assessment of these structures must consider the time dependent behavior of concrete. In this context, a numerical investigation is conducted to determine the critical buckling load and the stress distribution in sections subject to creep and shrinkage of concrete. The guidelines used are those from the American Concrete Institute. It is concluded that the maximum stress induced in the reinforcement is 1.14% of the steel yield stress. Therefore, no yielding of the reinforcement is registered to the examined case which ensures safety against permanent deformation. During the elapsed time of 7500 days, the modulus of elasticity of concrete decreased by 53% and the critical buckling load 40%. The results obtained can be applied to similar cases through the slenderness index and the reinforcement ratio.

This paper describes an integrated experimental and numerical investigation on the behavior of lapped, grouted connections for modularized construction of safety-related nuclear reinforced concrete (RC) shear wall structures. The novel lapped geometry of the proposed connection provides “face-to-face” (rather than “end-to-end” or “butt”) joint interfaces with large grouted construction tolerances and large surfaces to develop the required continuity of the strength and stiffness of the wall. A total of 5 modular beam specimens and one state-of-practice (monolithic) beam specimen were tested under 3-point simply supported monotonic loading conditions. These beam specimens represented horizontal slices taken out of the length of a nuclear shear wall structure. Continuum finite element analyses were conducted to compare with the experimental test results and to develop information regarding the effects of material differences between the specimens. The experimental and numerical results showed that adequate clamping of the connection, as well as additional longitudinal beam reinforcement on both sides of the grout joint, are necessary to achieve the desired “strong” connection behavior with full strength and stiffness continuity between adjacent RC modules.