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Experimental study on the shear strength of reinforced concrete beams cast with Lava lightweight aggregates

Nawaz W., Abdalla J. A., Hawileh R. A., Alajmani H. S., Abuzayed I. H., Ataya H., Mohamed H. A.

Archives of Civil and Mechanical Engineering

2019

Vol. 19, no. 4

981--996

This paper investigates experimentally the shear strength behavior of reinforced concrete (RC) beams cast with Lava lightweight aggregates as a replacement of normal coarse aggregates. A total of 24 shear deficient RC beams were fabricated and cast with normal (NWC) and lightweight (LWC) concrete and tested under three-point bending after 28 and 56 days. The variables of the experimental program include type of aggregate, concrete compressive strength, and beam size. The experimental results include load–deflection response curves along with failure mode for each beam specimen. The experimental result showed that all beams failed in a similar fashion, due to diagonal tension shear crack. However, a larger number of cracks with less spacing occurred in the LWC beams as compared to NWC specimens. Based on the experimental results, it can be also concluded that LWC specimens tested after 56 days achieved comparable shear strength results to that of NWC beams. In addition, the strength reduction factor (l) for LWC specimens was in the range of 0.69–0.98. The concrete shear strength (Vc) was also predicted using different shear design provisions and the results has shown that Eurocode 2 provisions yielded the lowest C. O.V. of 2.3 and 10.2% for NWC and LWC specimens, respectively.

Dry magnetic separation of nepheline syenite ores

Ibrahim S. S., Mohamed H. A., Boulos T. R.

Physicochemical Problems of Mineral Processing

2002

Vol. 36

173-183

Different types of dry high intensity magnetic separators are applied to remove the iron bearing contaminants from two nepheline syenite samples. Ding’s cross belt separator was applied in this study as a “pick up” separator, while “Carpco” induced roll was employed as a free fall kind of separator, that is widely used with dry sand size materials. Magnaroll magnetic separator, the latest design by Boxmag Rapid that uses rare earth permanent magnets for high intensity magnetic separation, was also applied. The main parameters affecting the separation efficiency of these machines were studied. It was found that Magnaroll separator was of high performance, as compared with the other separators. It was possible to produce clean concentrates containing 0.24% and 0.28% iron oxide from original samples containing 6.0% and 5.3% Fe2O3, respectively. These products are acceptable as glass grade materials in amber glass and fiberglass industries, as well as for ceramic purposes.

Stosowano różne, działające na sucho, separatory magnetyczne o dużej intensywności pola magnetycznego do usuwania minerałów żelazonośnych z dwóch rud nefelinowo-sjenitowych. Do separacji wstępnej użyto separatora typu Dingo o skrzyżowanych taśmach. Jako separator właściwy zastosowano separator indukcyjny bębnowy typu Carpco, który jest szeroko stosowany do przeróbki piasków na sucho. Użyto także separator magnetyczny typu Magnaroll, najnowszy model separatorafirmy Boxmag – Rapid, który posiada stałe magnesy wykonane z pierwiastków ziem rzadkich. Badano wpływ głównych parametrów na proces separacji magnetycznej. Stwierdzono, że najlepsze wyniki uzyskuje się stosując separator Magnaroll. Wytworzono koncentraty zawierające 0,24% i 0,28% tlenków żelaza z nadawy zawierającej odpowiednio 6,0 i 5,3% Fe2O3. Uzyskane produkty mogą być stosowane do produkcji szkła miodowego oraz włókna szklanego oraz ceramiki.