The production of environmentally friendly, sustainable plain concrete slabs is an essential requirement in this work. It is interesting to note that the ions of lead of wastewater loaded into rice husks can be used as an additive for plain concrete slabs to improve the flexural strength, as well as the workability of plain concrete slabs (or walls), which are produced by using Lead-loaded rice husk material as an additive substance in protective shields for the establishment of hospital radiology rooms. The results show that flexural strength for plain concrete slabs begins with a relative increase until it reaches breakdown. The results at age of 28 days also show that by increasing the proportion of Lead-loaded rice husk added to plain concrete slabs, the flexural strength gradually increases until it reaches one-third of the value of reference plain concrete slabs at a specific ratio, then decreases sharply until the slabs fail. These results provide a novel approach to managing toxic waste and propose an easy, simple, effective, economical, and environmentally friendly way to get rid of more than one type of waste and reach the concept of zero residue level.
This study is devoted to investigate experimentally the ultimate strength capacity performance of seven dapped ends simply supported reinforced concrete beams with a (length, height, and width) dimension of (1200, 240, and 130) mm, either solid cross section or top/bottom hollow opening/s. One-point load test method results a different crack patterns of multi types of failure with varying intensity. It is found that the beams strength capacity values with openings less than the solid beams by 5-10%, while the deflection values of solid cross section beam contrary increased by 11-30%. Also, for the same location of opening the increase in hollow openings reduce the capacity load by 4.5-10%, but increase the deflection values by 6-12.5%. Finally, the beams with opening located at the compression zone decrease the load capacity and increase the deflection values by 5% than the beams with opening at tension zone. Therefore, this study handed to the civil engineering designer using the dapped ends beams in bridge construction structures under effect of static loads, “for the necessary purposes of installing power supply cable or water pipe, the authors recommended using beams with opening to be located at bottom fiber tension zone”.
Reinforced polymer bars could potentially be used with fiber as a strengthening technology in MRPC. The main objective of this paper is to study the influence development of the flexural behavior of MRPC beams after 120 days of virtual corrosion-exposure in riverine simulated circumstances using GFRP and CFRP bars. Nine beams were tested via a two-point loading method up to failure, 1200 mm long, (200x100mm) cross-section. The water/binder is chosen to be 0.14 by weight. Silica fume was replaced by 8% weight of cement. The dose of superplasticizer used to the total binder weight was 0.41 percent. Three types of flexural reinforcement ratios were used individually per each cross-section; GFRP, CFRP, and traditional steel rebar, with a nominal diameter of 10 mm. The compressive strength of MRPC is 80 MPa. The experimental evidence indicates that GFRP and CFRP bars used with MRPC have higher tensile strength and anti-corroded bars. Also, the load results indicate that CFRP bars are more efficient than GFRP bars and steel rebar. Finally, the behavior of MRPC beams neither GFRP and CFRP bars submerged in Tigris river water did not chemically affect. The author recommended replacing steel rebar with GFRP and CFRP bars to improved structural behavior.
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