This article introduces simulations of theoretical material with controlled properties for the evaluation of the effect of key parameters, as volumetric fractions, elastic properties of each phase and transition zone on the effective dynamic elastic modulus. The accuracy level of classical homogenization models was checked regarding the prediction of dynamic elastic modulus. Numerical simulations were performed with the finite element method for evaluations of the natural frequencies and their correlation with E_d through frequency equations. An acoustic test validated the numerical results and obtained the elastic modulus of concretes and mortars at 0.3, 0.5 and 0.7 water–cement ratios. Hirsch calibrated according to the numerical simulation (x = 0.27) exhibited a realistic behavior for concretes of w/c = 0.3 and 0.5, with a 5% error. However, when the water-to-cement ratio (w/c) was set to 0.7, Young’s modulus displayed a resemblance to the Reuss model, akin to the simulated theoretical triphasic materials, considering matrix, coarse aggregate and a transition zone. Hashin-Shtrikman bounds is not perfectly applied to theoretical biphasic materials under dynamic situations.

This paper significantly extends investigations into internal damping ratios in both undamaged and damaged conditions for normal-strength concretes (NSCs) and high-strength concretes (HSCs). This study examines concretes with compressive strengths ranging from 42 to 83 MPa. Cyclic loads were applied using a servo-controlled hydraulic testing machine, and for each cyclic step, the dynamic elastic modulus ($E_d$) and internal damping ratio ($\xi$) were determined through acoustic tests. The results show that the normal-strength concretes ($f_c=42$ MPa) exhibited an undamaged internal damping ratio of $\xi =0.5\%$, reaching a maximum of $\xi =2.5\%$ at a damage index of 0.8. Conversely, the high-strength concrete mixtures ($f_c=83$ MPa) showed an undamaged internal damping ratio of $\xi =0.29\%$, with a peak value of $\xi =0.93\%$ at a damage index of 0.32. The initial internal damping values are influenced by porosity and transition zones, which affect the material behavior under cyclic loads. Progressive damage leads to increased Coulomb damping due the cracking process. Few studies have quantified and comprehended the internal damping ratio under cyclic loading-induced damage, and this research advances our understanding of NSC and HSC behavior under dynamic excitation and damage evolution, especially in impact scenarios.

Recently, the feasibility of producing cementitious nanocomposites has been widely investigated. Cement-based nanocomposites with the incorporation of nano silica [¹ 1 L. U. D. Tambara et al., “Effect of the nanosilica source on the rheology and early-age hydration of calcium sulfoaluminate cement pastes,” Constr. Build. Mater., vol. 327, pp. 126942, Jul. 2022, http://dx.doi.org/10.1016/j.conbuildmat.2022.126942. http://dx.doi.org/10.1016/j.conbuildmat.... 2 Q. Fu, X. Zhao, Z. Zhang, W. Xu, and D. Niu, “Effects of nanosilica on microstructure and durability of cement-based materials,” Powder Technol., vol. 404, pp. 117447, May 2022, http://dx.doi.org/10.1016/j.powtec.2022.117447. http://dx.doi.org/10.1016/j.powtec.2022.... ]-[³ 3 M. Kooshafar and H. Madani, “An investigation on the influence of nano silica morphology on the characteristics of cement composites,” J. Build. Eng., vol. 30, pp. 101293, Sep. 2020, http://dx.doi.org/10.1016/j.jobe.2020.101293. http://dx.doi.org/10.1016/j.jobe.2020.10... ], carbon nanotubes [⁴ 4 L. Silvestro, A. S. Ruviaro, P. R. Matos, F. Pelisser, D. Z. Mezalira, and P. J. P. Gleize, “Functionalization of multi-walled carbon nanotubes with 3-aminopropyltriethoxysilane for application in cementitious matrix,” Constr. Build. Mater., vol. 311, pp. 125358, Oct. 2021, http://dx.doi.org/10.1016/j.conbuildmat.2021.125358. http://dx.doi.org/10.1016/j.conbuildmat.... 5 L. Silvestro, G. T. S. Lima, A. S. Ruviaro, P. R. Matos, D. Z. Mezalira, and P. J. P. Gleize, “Evaluation of different organosilanes on multi-walled carbon nanotubes functionalization for application in cementitious composites,” J. Build. Eng., vol. 51, pp. 104292, Feb. 2022, http://dx.doi.org/10.1016/j.jobe.2022.104292. http://dx.doi.org/10.1016/j.jobe.2022.10... 6 J. Huang, D. Rodrigue, and P. Guo, “Flexural and compressive strengths of carbon nanotube reinforced cementitious composites as a function of curing time,” Constr. Build. Mater., vol. 318, pp. 125996, Nov. 2022, https://doi.org/10.1016/j.conbuildmat.2021.125996. https://doi.org/10.1016/j.conbuildmat.20... ]-[⁷ 7 F. Gao, W. Tian, Z. Wang, and F. Wang, “Effect of diameter of multi-walled carbon nanotubes on mechanical properties and microstructure of the cement-based materials,” Constr. Build. Mater., vol. 260, pp. 120452, Nov. 2020, http://dx.doi.org/10.1016/j.conbuildmat.2020.120452. http://dx.doi.org/10.1016/j.conbuildmat.... ], graphene [⁸ 8 G. Mishra, A. Warda, and S. P. Shah, “Carbon sequestration in graphene oxide modified cementitious system,” J. Build. Eng., vol. 62, pp. 105356, Jul. 2022, http://dx.doi.org/10.1016/j.jobe.2022.105356. http://dx.doi.org/10.1016/j.jobe.2022.10... 9 X. Kong, R. Wang, T. Zhang, R. Sun, and Y. Fu, “Effects of graphene oxygen content on durability and microstructure of cement mortar composites,” Constr. Build. Mater., vol. 354, pp. 129121, Jul. 2022, http://dx.doi.org/10.1016/j.conbuildmat.2022.129121. http://dx.doi.org/10.1016/j.conbuildmat.... ]-[¹⁰ 10 A. G. Alex, A. Kedir, and T. G. Tewele, “Review on effects of graphene oxide on mechanical and microstructure of cement-based materials,” Constr. Build. Mater., vol. 360, pp. 129609, Nov. 2022, http://dx.doi.org/10.1016/j.conbuildmat.2022.129609. http://dx.doi.org/10.1016/j.conbuildmat.... ], and nano titanium [¹¹ 11 M. Orakzai, “Hybrid effect of nano-alumina and nano-titanium dioxide on mechanical properties of concrete,” Case Stud. Constr. Mater., vol. 14, pp. e00483, Jun. 2021, http://dx.doi.org/10.1016/j.cscm.2020.e00483. http://dx.doi.org/10.1016/j.cscm.2020.e0... 12 L. Ingrisova and P. Hajek, “Contribution of TiO2 and ZnO nanoparticles to the hydration of Portland cement and photocatalytic properties of High Performance Concrete,” Case Stud. Constr. Mater., vol. 16, pp. e00965, Nov. 2022, http://dx.doi.org/10.1016/j.cscm.2022.e00965. http://dx.doi.org/10.1016/j.cscm.2022.e0... ]-[¹³ 13 D. Jegatheeswaran, S. M. Subash, C. S. Ravi, B. Rajalakshmi, and D. Z. Rahman “Investigational work on self-cleaning cement mortar with titanium dioxide in partial replacement of cement,” Mater. Today Proc., vol. 65, no. Pt 8, pp. 3161-3165, 2022, https://doi.org/10.1016/j.matpr.2022.05.356. https://doi.org/10.1016/j.matpr.2022.05.... ] stand out in the scientific field. Incorporating nanomaterials aims to produce composites with properties that focus on applicability (e.g., self-sensing application) or enhance mechanical properties. However, the application of these nanomaterials is conditioned to some limitations associated with the synthesis in large quantities to consolidate their incorporation in mortars and concretes. Therefore, most studies of nanomaterials are carried out in cementitious pastes [¹⁴ 14 L. Silvestro and P. J. P. Gleize, “Effect of carbon nanotubes on compressive, flexural and tensile strengths of Portland cement-based materials: a systematic literature review,” Constr. Build. Mater., vol. 264, pp. 120237, Dec. 2020, http://dx.doi.org/10.1016/j.conbuildmat.2020.120237. http://dx.doi.org/10.1016/j.conbuildmat.... ].

In Brazil, there is a shortage of approximately 5.80 million residences, a challenge that intensified during the pandemic. Since 2013, there has been a mandate to implement specific performance criteria in residential constructions. However, many construction firms face difficulties in meeting these standards, especially concerning sound insulation in partition elements. This work aims to assess the airborne sound insulation performance and compliance with legal standards in new residential buildings through measurements and simulations. In particular, subsidized housing units for low-income populations are studied, which are eligible for reduced taxes on building loans. These buildings are typically made of hollow ceramic blocks with vertical perforations as separating walls, a commonly used national building material. Three buildings located in Guarapuava, a southern city in Brazil with a population of approximately 183,000 residents, were selected for this purpose. Measurements were conducted following ISO 16283-1 guidelines, whereas simulations were performed using ISO 12354-1, initially assuming a uniform plate but also exploring an alternative model that considers orthotropic behavior with analytical expressions. The calculations considered both static and dynamic moduli of elasticity. The results indicated that all the units failed to meet the specified standards. The measured $D_{nT,w}$ values were below the required thresholds, obtaining 42 < 45 dB for Building B1, 40 < 45 dB for Building B2, and 38 < 40 dB for Building B3. The predicted $D_{nT,w}$ values agreed well with the measured values when considering orthotropy with a dynamic elastic modulus. However, discrepancies were observed in the spectral analysis, especially at lower and higher frequencies. The findings suggest refraining from employing single-leaf partition walls made of vertical hollow ceramic blocks in such buildings. Improving sound insulation necessitates embracing a comprehensive strategy that takes into account the separating element, flanking paths, and the room geometries.