Effect of Hydrothermal Carbonization of Coconut Coir on Mechanical Properties of Cement Mortar

Hydrothermal carbonization (HTC) involves a thermochemical process at high temperature to reduce lignin and extractive in organic material using water as a medium. HTC produces a solid product known as hydrochar. Utilization of coconut coir in the concrete or mortar is an alternative to reducing agriculture waste. The application of natural fibers as aditif material in concrete and mortar effect the characteristics of cement mortar. The aim of this study is to investigate the impact of introducing coconut coir on mechanical properties of cement mortar at 28 days. This research used coconut coir, with a diameter of 0.420-0.149 mm. First, the coconut coir was boiled in a 5% potassium hydroxide (KOH) solution at 80°C for 30 minutes. Then followed the hydrothermal carbonization process for 1, 2, and 3 hours at 160°C. This research used a sand-to-cement ratio of 1:2.75 (by weight) and a water-to-cement ratio of 0.46. The hydrochar used in this study was 1% of cement (by weight). In the context of this research, physical and mechanical properties were observed such as flowability, compressive strength, flexural strength, and water absorption. The duration of the hydrothermal carbonization affected flowability, compressive strength and water absorption. It enhanced flowability, compressive strength, and water absorption. On the other hand, the hydrothermal carbonization duration increased as the flexural strength decreased.