No abstract

No abstract

Abstract-An experimental investigation of radiation shielding properties of high performance concretes (HPCs) was mad under effect of different variables. HPCs were produced from different normal and heavyweight aggregate with three low water-to-cementitious materials ratios (w/cm) to obtain different compressive strengths. The linear attenuation coefficients were measured at 0.663 MeV γ-rays energy of 137 Cs radioactive using NaI (Tl) scintillation detector. It was found that the compressive strength of heavyweight HPCs plays an important role in enhancing the attenuation of γ-rays. The compressive strength and attenuation of γ-rays have a near to linear relation. While in the normal concrete, the strength has no effect on the attenuation of γ-radiation. The mass attenuation coefficients were also compared with the values obtained by the United States National Institute of Standards and Technology (NIST). The comparison showed a reasonable agreement. It was observed that the attenuation of γ-rays is considerably affected by concrete density.Index Terms-High performance concrete, γ-attenuation coefficients, aggregate types, compressive strength, water-to-cementatious materials ratio.

The frequency and severity of climate change are projected to increase, leading to more disasters, increased built environment system (BES) vulnerability, and decreased coping capacity. Achieving resilience objectives in the built environment is challenging and requires the collaboration of all relevant sectors and professionals. In this study, various stakeholders were engaged, including governmental authorities, regulatory bodies, engineering firms, professionals, contractors, and non-governmental and non-profit organizations (NGOs and NPOs, respectively). The engagement was carried out through the answering of a questionnaire survey that reflects their perceptions about climate change adaptation, the built environment resilience qualities (RQs), and the degree of resilience of the existing built environment and their perceived capacities. The results were analyzed using several statistical tests. The results revealed that advancing public understanding and management tools, reducing economic losses, and developing necessary plans still require improvement. Additionally, the BESs were ranked concerning accepting the change and uncertainty inherited from the past or generated over time. This study emphasized the perception that the decision-making domain is crucial for delivering a reflective built environment. Additionally, features such as advancing public understanding and management tools, reducing economic losses, and developing necessary plans still require improvement. Furthermore, there is a belief in the importance of the task forces within the community as part of an emergency response plan, and a less reflective system would have less recovery speed. Therefore, the rapidity characteristic of a built environmental system to accept the change and uncertainty inherited from the past or generated over time is correlated to the system’s reflectivity quality. This study emphasizes the significant correlation between the different RQ traits. It also encourages researchers to formulate more objective methods to reach a set form for measuring RQs as an engineering standard.