Safety-critical sounds at job sites play an essential role in construction safety, but hearing capability is often declined due to the use of hearing protection and the complicated nature of construction noise. Thus, preserving or augmenting the auditory situational awareness of construction workers has become a critical need. To enable further advances in this area, it is necessary to synthesize the state-of-the-art auditory signal processing techniques and their implications for auditory situational awareness (ASA) and to identify future research needs. This paper presents a critical review of recent publications on acoustic signal processing techniques and suggests research gaps that merit further research for fully embracing construction workers’ ASA of hazardous situations in construction. The results from the content analysis show that research on ASA in the context of construction safety is still in its early stage, with inadequate AI-based sound sensing methods available. Little research has been undertaken to augment individual construction workers in recognizing important signals that may be blocked or mixed with complex ambient noise. Further research on auditory situational awareness technology is needed to support detecting and separating important acoustic safety cues from complex ambient sounds. More work is also needed to incorporate context information into sound-based hazard detection and to investigate human factors affecting the collaboration between workers and AI assistants in sensing the safety cues of hazards.
The suitability of palm kernel shell and quarry dust as coarse and fine aggregates in the concrete were investigated. The materials were pretreated which was followed with determination of physical properties of palm kernel shells and quarry dust as aggregates. A mix design following ACI 211 was used for the concrete mix proportion. Apart from control mix, two replacement levels of coarse aggregates at 50% and 100% with palm-kernel shells at 100% quarry dust were examined. Results show that compressive strength decreased with increase in proportions of palm-kernel shell. For 100, 50, and 0% palm kernel shells in the concrete containing 100% quarry dust, the compressive strength at 28 days were 15.06 N/mm 2 , 17.72 N/mm 2 , and 35 N/mm 2 respectively which satisfied the minimum requirement for the production of lightweight concrete. This grade of concrete could be used where low stress concrete is required. Based on the optimum compressive strength of palm kernel shellquarry dust aggregates concrete, the following inferences were made that the values obtained for specific gravity, water absorption, bulk density, moisture content of palm-kernel shell and quarry dust fall within the range specified for a light weight aggregate. This confirmed that palm-kernel shell and quarry dust could be used as substitute for coarse and fine aggregate respectively to produce lightweight aggregate concrete in non-load bearing structures and in lightweight structural concrete at 1: 1.31 : 2.55 mix ratio.
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