Hemp hurd, a material from the industrial hemp plant, is gaining recognition for its diverse applications. It constitutes a significant portion of the hemp stalk, traditionally processed for its fibers and seeds. As interest in sustainable resources grows, hemp hurd’s inherent properties are being re-evaluated for modern product development.
What Exactly is Hemp Hurd?
Hemp hurd, also known as shives, constitutes the woody inner core of the hemp plant’s stalk. This part of the plant is distinct from the long, strong outer bast fibers that encase it. The hurd is a byproduct resulting from the separation of these components, making up approximately 60% to 80% of the hemp stem by weight.
Hemp hurd is lightweight, porous, absorbent, and insulative. Its natural composition primarily consists of cellulose (40-52%), hemicellulose (18-33%), and lignin (15-28%).
These components contribute to its structural integrity. Its porous nature allows it to absorb moisture and regulate humidity, and its structure provides natural sound dampening qualities.
From Plant to Product: The Production Process
Hemp hurd production involves specific processing techniques. After harvest, the hemp stalk undergoes a process to separate its different parts.
Decortication mechanically breaks down the hemp stalk, detaching the woody hurd from the fibrous outer layers. This process isolates clean hurd, free from other plant matter. The transformation results in discrete, low-dust particles, ready for further processing or direct application.
This mechanical separation allows for efficient utilization of the entire hemp stalk. While bast fibers are collected for textiles, the hurd is simultaneously prepared for use. The resulting hurd product is then sized for its intended use.
Diverse Applications of Hemp Hurd
Hemp hurd’s absorbent, insulative, and lightweight properties enable diverse applications. A prominent use is in building materials, particularly hempcrete. Hempcrete combines hemp hurd with a lime-based binder and water, creating a lightweight composite material for insulation and non-structural panels. This material regulates indoor temperature and moisture, and contributes to sound insulation.
Beyond hempcrete, hemp hurd is used in other construction products like insulation panels and eco-friendly flooring. It offers thermal and acoustic benefits. Hempcrete can demonstrate fire resistance due to the lime binder, and the material also resists pests and mold.
Hemp hurd’s high absorbency makes it ideal for animal bedding. It can absorb moisture up to four times its dry weight, exceeding wood shavings by 50%. This capacity, combined with its natural ability to control odors and low dust content, makes it ideal for livestock and pet bedding.
Its absorbent qualities extend to industrial uses, serving as an effective material for spill clean-up, including oil and chemical spills. Its porous structure effectively captures liquids and gases. Additionally, hemp hurd’s antibacterial properties aid food preservation by managing excess moisture and inhibiting decay.
Hemp hurd is used in bioplastics as a filler, contributing to biodegradable composites. It can also be processed into paper pulp, yielding a thicker and softer product compared to fiber-based paper. In horticulture, hemp hurd finds use as a growing medium and mulch, improving soil structure, enhancing drainage, and supporting beneficial microbial networks.