Concrete Characteristics Using Destructive and Non-Destructive Tests

Adejoh Benjamin Ochola¹, Sa’eed Abdul- Basit Ahmad ², Hadiza Ali³

ABSTRACT

Mechanical resistance and deformation are important characteristics of concrete, because they play a great role not only for the stability, but also for the durability of the structures. When concrete is subjected to the action of a rapidly increasing load, it behaves like a brittle material. On the one hand, its rupture is not preceded by significant deformations and on the other hand, its tensile strength is much weaker than its compressive strength. The tensile strength even vanishes completely if shrinkage cracks have developed. This paper presents an experimental study in order to determine some characteristics of the concrete made for the production of reinforced concrete beams. To this end, cylindrical specimens of dimensions 16 x 32 cm were prepared in the laboratory using local materials for mechanical characterization by destructive and non-destructive tests. Splitting test was carried out to determine experimentally the tensile strength of concrete. Schmid rebound hammer and compression machine were used to determine the compressive strength of concrete, as well as its longitudinal elastic modulus (Young’s modulus) at the age of 28 days. The results obtained by the various tests were compared to validate the measured values. Indeed, the concrete resistance measurements from the rebound hammer test were compared with those obtained by the compression test. Likewise, the concrete tensile strength values of the splitting test were compared with those found from the compression test.

Keywords: Concrete; Cylindrical specimens; Splitting test; Schmidt rebound hammer; Elastic modulus; Compressive strength

Development and Comparative assessment of a Low Power Robotic Mower Using Internet of Things (IOT) against Conventional Electric Powered Mower

Obokhai Kess Asikhia^a, Lucky Michael Osite^b, and Augustine Edet Ben^a

ABSTRACT

The design and development of a low-power robotic lawn mower employed the user’s needs-centered approach to identify the need for a low-power robotic mower. The system comprised of three build phases: mechanical fabrication, building of electrical circuit, and software development, which involved programming using C and C++. The developed system was tested by comparing it with conventional electrical mowers on mapped-out dry and fresh fields under similar test conditions. The result of the assessment showed that the developed mower completed the dried and fresh fields under 348 and 306 seconds, while the conventional mower completed the same field under 127 and 78 seconds respectively. The effective capacity, speed of operation, cutting efficiency, and performance index of the robotic mower were recorded as 0.0086 and 0.010 m²/s, 0.0057 and 0.0049 m/s, 65 and 60%, and 0.47 and 0.50 under dried and fresh grasses, respectively. Meanwhile, the conventional mower showed operational speeds of 0.016 and 0.019 m/s, cutting efficiency of 95 and 90%, and performance indexes of 0.224 and 0.342 for dried and fresh grass conditions, respectively. The better performance of the conventional mower was a function of its higher input power of 1000 watts compared to the low power of 120 watts of the developed robotic mower.

A Mobile Phone-based Self-Screening and Recovery Tool for Internet Addiction Disorder in Persons 

Fidelis I. Onah ^1* and Samuel Ekong²

ABSTRACT

This research paper implements a simple interactive browser-based, mobile friendly web application which screens persons of all age groups for Internet Addiction and prescribes a recovery therapy for severe symptoms. Data on socio-demographic indicators, Internet usage, psychosomatic symptoms and quality of life of the user are automatically collected as the user fills-in the self-administered questionnaire based on Young’s Internet Addiction Test (YIAT) and the 5-point Likert scale. Object oriented design methodology is required to support applications for devices like cell phones, pagers and personal digital assistants. Since the Android mobile application development is based on Java language codes, therefore, normal Java Integrated Development Environments (IDEs) and Google-enabled Android Java libraries were used to render services on the mobile devices. Other development tools used are Google forms for presenting the Internet Addiction questionnaire to the users; Spreadsheets for retrieving the data collected from the Google forms and generate a score based on user response; and Gmail for the medical team to automatically generate the test results and send as mail to the users. The research work includes a trusted recovery therapy which addicted individuals can access as email at the comfort of their homes. The work further incorporates a means of printing out a record of progress after a user’s session. In these periods of the global pandemic, an online screening, evaluation and therapeutic care can save you time and money; and even improve your mental health.

Keywords: Diagnostic Questionnaire, Healthcare, Internet Addiction, Mobile App, Self-Care, Screening, Therapeutic Care, Web App