# Development of Fiber Reinforced Sustainable Dredge Bricks
## 1 Introduction
To create a stabilized dredged material brick with a compression strength greater than 1000 psi while minimizing the use of Portland cement, a recent study found an appropriate combination of Portland cement, hydrated lime, and fly ash with dredged material. After testing the various mixtures, using only 10% by weight of Portland cement was reported to be the optimum ratio, as this mixture reached a compressive strength of approximately 1179 psi [11]. Other studies have identified various types of natural and synthetic fibers that could improve the compressional strength [12; 13; 14]. [PERSON] et al. reported on mixtures of polyester fibers of 12 mm in length with soil at relative amounts of fiber ranging from 0-1% and showed that inclusion of polyester fibers increased the strength of the soil until the ratio of fibers added was at 0.5%. After 0.5%, the strength would decrease if any more fibers were added to the soil [12]. [PERSON] et al. tested the effects of lime, fly ash, and polyester fibers being added to soil. The strength of the soil was tested with 0%, 0.5%, 1%, 1.5%, and 2% of polyester fibers added to it. The results showed that when adding 1.5% of fibers, the tensile strength was 135% greater in comparison with the soil with no fibers. The results for the compressive strength test closely related the results from the tensile strength tests [15]. [PERSON] et al. found that poly(vinyl alcohol) (PVA) fibers are another type that can be used in fiber-reinforced concrete. They reported that addition of 1% of PVA fiber and 4% cement sand resulted in two times the increase in strength [16]. Good adhesive properties to cement and high anti-alkali characteristics makes it interesting as a soil reinforcing material. Other studies found that Kenaf, a natural fiber obtained from the _Hibiscus cannabinus_ plant found in Southern Asia, had an absorption of 307%, an elastic modulus of 136 GPa,and a tensile strength of 1000 MPa [12]. The study revealed that the addition of Kenaf improved the flexural strength at higher lengths of fiber while it decreased the thermal conductivity when longer fibers were used within CEB [12]. When fiber content ranging from 0.2% to 0.8% by mass was added, Kenaf was also shown to reduce cracks within CEB improving their mechanical properties and resulting in better building materials than unreinforced blocks for masonry structures [17]. Despite these results, fibers were also found to decrease the compressive strength in CEB making the compressive strength inversely proportional to the fiber content [12]. In addition, the location dependent variations of the soil properties of the dredged material also introduces a unique problem to DM reuse. For dredged material from different waterways, or even from different parts of the same water system, consideration will have to be made in the composition of the soil when utilizing any mixture design. Our team recently tested the stabilization of local dredged materials using a tailored bio-enzyme stabilizer, hydrated lime, quicklime, Portland cement, and fly ash, and found that adding Portland cement increased the strength of the material most dramatically [18]. However, the longevity of a DM stabilization was questioned, hence the need to improve the resistance to erosion in a cost-effective manner. The addition of a coating to CSEB should be considered. Multiple types of coatings for the purpose of improving the bricks' resistance to weathering and erosion can be studied [19; 20]. For example, Eviro-Crete Series 156 produced by Tnemec is a modified waterborne acrylate, typically used for concrete or standard masonry units, that is used to fill in minor hairline cracks and provide protection against driving rainfall. The concentration of Volatile Organic Compounds (VOCs) in the Enviro-Crete measures in at 49 g/liter, significantly lower than the 250 g/liter limitation set by the Environmental Protection Agency (EPA) for exterior coatings [21]. Another example of a commercially available coating is a lime base coating.