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Abstract. This study investigates the risk of flood on selected critical infrastructure in a flood-prone catchment in Sabah, Malaysia. Kota Marudu, located in the Bandau floodplain, one of the Sabah's northern water catchments, was selected as the study site due to its frequent flood occurrence and large floodplain coverage. Two of its largest rivers, namely Sungai Bongon and Sungai Bandau, tends to flood during rainy season and cause temporary displacements of thousands of people living in the floodplain. A total of 362 respondents participated in the questionnaire survey in order to gather information on historical flood occurrence. Three flood depth groups were determined, which are 1) less than 0.3 meter, 2) 0.3 -0.6 meter and 3) more than 0.6 meter, while three categories of critical infrastructure were defined, namely transportation system, communication system and buildings. It is found that the transportation system encounters the most severe impact as flood inundation increases, where 92% of the respondents believe that the transportation access should be abandoned when flood depth is more than 0.6m. The findings of this study will be used for detailed risk assessment, specifically on the vulnerability of the critical infrastructures to flood in this floodplain.

Abstract. This research was carried out to determine the optimum percentage of eggshell ash and rice husk ash (RHA) as partial cement replacement. The samples were tested for its mechanical properties by using concrete grade G30 with cube mould (100 mm x 100 mm x 100 mm) and prisms (100 mm x 100 mm x 500 mm). The samples were mixed with eggshell ash and RHA admixture with different proportions (2%:8%, 4%:6%, 6%:4%). Several types of test were conducted towards the samples, which are the slump test, compressive and flexural test. Based on previous researches, the strength of concrete reduced as replaced with eggshells. Most of the researches show the similar trend when partial cement is replaced using eggshell ash. Thus, to increase the strength, an admixture which has pozzolanic reactivity called rice husk ash (RHA) is introduced into mix design which has been proved can help to improve the strength of concrete.

Flood event is one of the natural disasters that increasingly threaten the safety of the people in an area. Critical infrastructure albeit important, has been shown to be vulnerable to flooding and damages to critical infrastructure element may affect large areas over a longer time period. Critical infrastructures play an important role in functioning of industries and communities and also responding against flooding to reduce their impacts. Critical infrastructures such as hospital, school, road networks and other infrastructures are important during flood event to serve as emergency services. It was found that there is difference in understanding the concept of vulnerability with varying assessments and different view. This paper briefly reviews the concept of vulnerability and discusses on the approach used for flood vulnerability of critical infrastructure by past researchers to identify and fortify the vulnerable critical infrastructure ahead of time reducing the potential damage due to flood. This paper focuses the vulnerability of critical infrastructure during flood event and also describes several approaches with a discussion on the application of the approaches used and the relevance results.