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In this paper, fly ash and metakaolin as pozzolan while limestone powder and kaolin as filler material were used at replacement levels of 5%, 10%, 15%, and 20% by weight of cement and sand, respectively. The effects of these powders on the fresh property of mortar mixes were studied and reported. Superplasticizer dosages were determined from flow test on cement paste and mortar with different powder content. A total of 33 mixes were prepared, mixed, and tested. The mini slump cone and mini V-funnel box tests were used to assess the flowability of the fresh mortar. In addition, the effect of mineral admixture on setting time of the mixes was also evaluated. In this study, the optimum dosage of superplasticizer was determined based on the desired flowability for self compactability. Superplasticizer at higher dosages than optimum reduced the stability due to bleeding. The results confirmed the role of the mineral powders in determining the desired stability and the flowability of mortar mixes which is crucial for self compacting concrete.

The performance of structures such as bridges, machine foundations and base isolated buildings are very much affected by the condition of their elastic bearing supports, which eventually deteriorate due to wear and tear or which can be damaged during the service life of the structure. In this study, the dynamic parameters, namely natural frequencies and mode shapes are used to detect the deterioration of the elastic bearing supports of a simply supported bridge girder. For this purpose, force vibration testing was conducted on a reinforced concrete bridge girder supported at the ends by rubber bearings to simulate the actual conditions in a bridge deck. Three different levels of deteriorations were investigated namely that of no deterioration, partial deterioration, and full deterioration, whereby rubber with different stiffness was used to simulate the different deterioration levels. Vibration data were obtained for two cases i.e. an undamaged girder and a damaged girder after being subjected to a load exceeding its service limit for flexure. A direct relationship was observed between the dynamic parameters and the elastic bearing stiffness. Based on the results obtained in this study, the natural frequency of mode 3 is a good indicator of the deterioration in elastic bearing support conditions while mode 1 is the most sensitive to changes in support conditions. The Modal Assurance Criteria (MAC) index can be a useful indicator to identify different causes of deterioration in the structural system. In order to confirm and verify the observations, further tests were conducted on a different beam with more deterioration levels in the elastic bearing stiffness. The results support the deductions made regarding MAC and bending frequencies.

The main objective of this investigation is to determine the effect of palm diesel on concrete under accelerated laboratory conditions. Mortar samples of ordinary Portland cement (OPC), modified OPC with natural rubber latex, magnesium phosphate cement and epoxy-coated OPC were soaked in palm diesel. Samples were p prepared under different curing regimes and soaked in palm diesel for a definite period. Both visual and microscopic examinations were then made to ascertain the nature of the attack. The change in weight of the specimens was also recorded to quantify the degree of deterioration. The mortar samples containing OPC exhibited the highest degree of deterioration, whilst the epoxy-coated and magnesium phosphate samples were least affected. The degree of deterioration was also dependent on the curing regime. The principal cause of the deterioration was attributed to saponification by the free lime present in the set cement, forming a calcium soap. It can be concluded from the results of this preliminary investigation that surface treatment with epoxy or other suitable materials chemically resistant to palm diesel may inhibit the deterioration on the concrete. Furthermore, by using a different kind of cement that contains a substantially smaller amount of calcium than OPC, the attack of the palm diesel may be reduced or prevented.