Constr. Mater., Volume 1, Issue 1 (June 2021) – 6 articles

Reinforced Concrete (RC) buildings with masonry infills are a very common structural typology worldwide for civil, strategic, or productive use. Damage to infills may cause danger for human lives and strongly affects economic losses, as shown during past earthquakes. In the current literature, different approaches are available for modeling the in-plane response of infilled frames and different constitutive laws generally calibrated on experimental tests. On the contrary, few and recent studies proposed formulas that account for the main properties of infills influencing their in-plane behavior to lateral forces. This paper presents a study finalized to derive a reliable model that is able to predict the monotonic and cyclic response of RC infilled masonry frames. To this end, after a critical analysis of the available literature, the authors combine among them two models, one for the monotonic response and the other for the cyclic one, by showing their reliability with reference to different experimental cases. Then, at the end of the paper, the derived models are employed to assess the seismic vulnerability of infills throughout a proposed procedure based on the common pushover analysis approach. Full article

Glass-ceramics are advanced inorganic silicate materials that can be obtained by sintering glass powders using a careful temperature control to result in the densification, nucleation, and crystallization of the material. In the current work, three different samples were obtained starting from amorphous silicate materials derived from mixtures of metallurgical slag, coal fly ash, and glass cullet, mixed in different proportions. The as-received waste samples were heat-treated to high temperatures to achieve complete melting at 1200, 1300, and 1400 °C for two hours, performing a rapid cooling in order to yield an amorphous material (glass). The obtained frit was ball-milled to a powder, which was then cold pressed to obtain compact pellets. The thermal treatment of pellets was carried out at 800–1100 °C for 2 h followed by a cooling rate of 10 °C/min to obtain the final glass-ceramics. The microstructure of samples was evaluated with scanning electron microscopy (SEM), which showed heterogeneous conglomerates and clusters of ~20 microns. The formation of crystalline phases was corroborated by means of X-ray diffraction (XRD) analysis, showing the presence of anorthite in all samples. Depending on the sample composition, other crystalline phases such as augite, enstatite, and diopside were detected. Using the Debye–Scherrer equation, it was possible to find the average size of the nano-crystalline domains. The quantification of the non-crystalline or amorphous fraction was also performed. Additionally, the density and porosity of the materials were calculated using the procedures defined in the ASTM C373 and ASTM C20 standards, measuring density values in the range 2.2–3.1 g·cm⁻³. The apparent porosity was approx. 33% in the three materials. Raman spectroscopy analysis showed characteristic signals associated with crystalline phases containing alumina, silica, iron, and calcium. Overall, the study confirmed the possibility of obtaining glass-ceramics with fine (nanometric) crystal sizes from a combination of silicate waste and the capability of modifying the crystalline composition by changing the proportions of the different wastes in the initial formulations. Full article

Lightweight aggregate concrete is an innovative building material used to reduce the self-weight of a high-rise building. Recently, the use of lightweight aggregate in construction is increasing immensely due to its performance during an earthquake. Lightweight aggregate concrete (LWAC) is a solution for the achievement of sustainability in the construction sector, which helps us cut down the overall cost of a project in massive construction work (tall buildings and bridges). Additionally, using various industrial by-products and waste instead of natural aggregate allows us to reduce the negative impact on the environment. The development of lightweight aggregate concrete with its relevance is still prominent. The performance of lightweight aggregate on various properties of concrete is explored in this study. This study shows that the lightweight aggregate and waste materials of less density can be used for structural applications with a strength equivalent to that of normal weight concrete. The application and advantages of LWAC are also discussed in this study. The paper’s overall finding reveals that LWAC can be used in sustainable construction growth and reduce waste by using it as natural aggregate in concrete to maintain environmental sustainability. Full article

Tack coat application rates and testing conditions differ among nations and construction conditions because various tack coat materials are available. In this study, newer materials are optimized for addition to porous asphalt pavements exposed to torrential rainfall, which is common in South Korea. Interface shear strength (ISS) tests are used to define the optimum application rates (OARs) of tack coat materials generally used in South Korea, by reference to the Korean Design Standard (KDS), the Korean Construction Standard (KCS), and features of pavement construction and bonding. We performed ISS tests using asphalt mixtures with porosities of 3, 5, and 7% to explore the effect of porosity on shear strength. The ISSs associated with varying tack coat proportions were earlier determined by creating polynomial regression equations. Here, we develop a predictive model using a non-linear function to estimate the OAR of tack coat and compare our approach with the earlier polynomial regression analysis. Based on the ISSs, the golden section search method was applied to define the OARs afforded by the predictive polynomial function. We used the generalized reduced gradient algorithm to construct a nonlinear predictive function using data from the ISS tests. Finally, our comparative analysis showed that the predictive model using the non-linear function was superior to the polynomial model in terms of both error rate and predictive tendency. Full article

This paper reviews the history of the development of impressed current cathodic protection of atmospherically exposed reinforced concrete from the first trials in 1959 on bridges to recently installed systems on a wide range of structures around the world. The paper covers the research efforts, anode developments, control systems and monitoring sensors which are reviewed and their evolution explained. The research into the potential and actual side effects of cathodic protection currents in concrete are summarised. The development of standards and guidance on impressed current cathodic protection is also reviewed. Full article