The significant CO2 emissions that can be associated with cement manufacture is the primary cause of global warming. Thus, the authors and research groups are motivated by many factors to find long-term solutions to this problem. Geopolymer concrete is such type of concrete in which the primary binder has resulted from alkali activation of some source materials like fly ash, metakaoline, rice husk ash, and ground granulated blast furnace slag. Commonly, geopolymer concrete gives comparable mechanical strength properties to conventional concrete. The use of this type of concrete is restricted by the properties of the used source materials and the molar concentrations of the alkali activator. As a consequence, making investigations into the relevant structural behavior as a result of these variables are rich source of scientific research. The goal of this work is to provide a brief overview of the recent contributions that have dealt with the structural behavior of geopolymer concrete. The context of this paper was obtained to illustrate the main findings as well as the used source materials and some additional considerations.

An experimental study was conducted to investigate the behavior of composite concrete beams damaged and cracked under pure torsion, and then repaired by external strengthening. This was achieved using high strength Carbon Fiber Reinforced Polymer (CFRP) laminates bonded with epoxy four composite modify reactive powder concrete (MRPC) I-beams. Different types of section (Solid & with opening) were tested to obtain the effect of amount of CFRP laminate on beams ultimate torque behavior, angle of twist and failure modes. The results obtained showed that a significant effect of external high strength CFRP laminates on effectively restore of section solid, the range of 89.8% to 91.2% of ultimate torsional strength effectively restored as well as effectively restoring of section opening by 83.48%-86.67% of ultimate torsional strength. The repaired beams give high efficiency in ultimate torsional strength, and indicate that the adopted technique gives a good torsional strength.