## 1 Introduction  
Concrete is one of the most popular materials used in modern construction, and cement is known as the main binder of the concrete structure. However, using cement leads to a negative effect on the environment due to the emission of carbon dioxide generated during the production of cement, according to [PERSON] [1]. As a consequence, the influence of climate change, greenhouse effect, calamities have serious threats to human life and the environment. The demand for research regarding friendly environmental construction materials, a decrement the carbon dioxide emissions into the air, and a reduction of cost are important needs for sustainable development all around the world. Therefore, many works have been carried out to develop a new eco-friendly and green material used to alter cement in concrete. \"Geopolymers\" was a term invented by [PERSON] [2] in the 1970s which can be used to be describe new materials or alternative binders in concrete. Geopolymers were investigated by combining source materials such as slag, fly ash, and minerals to replace cement and alkaline solution. There are many advantages when using geopolymer composites, such as higher mechanical performance, low production cost, good properties like low creep and drying shrinkage, excellent fire resistance, and a low corrosion rate [3; 4; 5; 6; 7; 8]. Though geopolymer composites have good performance, their poor flexural and tensile properties are issues that need investigation. The combing of fibers in geopolymer mixtures is one of the best solutions to enhance these properties. In terms of ordinary concrete, cement, steel, glass, polypropylene and other fiber have been successfully used and applied in its structure. The embedding of fiber in concrete leads to the improvement of strength properties as well as control of the development of cracking in structural applications. Many works have indicated that the properties of concrete reinforced with fiber, such as compressive strength, flexural strength, tensile strength, toughness, ductility, fatigue behavior and creep behavior were improved significantly compared to concrete without fibers. [PERSON] et al. [9] presented the mechanical properties of glass fiber-reinforced geopolymer concrete. This work concludes that the presence of 0.03% glass fiber enhanced compressive strength and flexural strength by 6% and 16%, respectively. [PERSON] and [PERSON] [10] considered the influence of volume fractions from 0% to 1% of cotton fiber on the characteristics of geopolymer composites. Their study found that compressive strength of geopolymer paste increased at 0.5% and decreased at 0.7% and 1% of volume fraction of fiber. [PERSON] et al. [11] studied geopolymer concrete using slag as a source material and steel fiber. There is a decrease in compressive strength and an increase in flexural strength and splitting tensile strength when the volume fraction of fiber increases. The influence of steel fiber on geopolymer concrete composites using boroaluminosilicate was also found by yje research of [PERSON] et al. [12] and [PERSON] et al. [13]. Their results indicated that there was good adhesion between steel fiber, geopolymeric paste, and mortar. The increase in the compressive and flexural strength depends on the volume fractions of steel fibers used, and the microstructural analysis showed that there was a good interfacial bonding of the embedded fiber and the geopolymeric binder. In another study, the improvements in the strength of alkaline cement mortars reinforced with polypropylene fiber were investigated. [PERSON] et al. [14] carried out an experiment with mortar specimens with three types of source materials--slag, fly ash, and a fly ash/slag combination--to evaluate the mechanical properties of the alkaline mortars. A slight decrease of mechanical properties happened while using 0%, 0.5% and 1% of polypropylene fiber.