DASM Institute researches and recycles straw into sustainable sound insulation and thermal insulation materials

Dr. Vu Viet Dung and his colleagues at the DASM Institute have successfully researched and recycled straw, turning it into a new building material with superior sound insulation, sound absorption, and thermal insulation capabilities. This is truly an effective and positive direction in Vietnam amidst the current situation where tens of tons of straw are being burned and wasted every year.

Every year, Vietnam wastes 2-3 billion USD by burning straw

After each rice harvest, farmers in rural areas usually have the habit of burning straw to clear the fields before sowing the next rice crop. According to the farmers, the volume of straw is too huge, while the demand for using straw as fuel is almost gone, and the demand for using straw as livestock feed or composting is also very little. Composting straw using bio-products requires a lot of effort and extra cost, so farmers choose the fastest solution, which is burning it.

According to Mr. Tong Xuan Chinh, Deputy Director of the Department of Livestock Production - Ministry of Agriculture and Rural Development (MARD), the volume of post-harvest straw by-products in our country is currently very large, reaching up to 43 million tons/year. Only about 23% of that straw waste is used for livestock purposes, while about 77% is being burned. Accordingly, on average, we waste 2-3 billion USD each year by burning it.

Burning straw not only wastes raw material sources, hardens the soil, but also causes environmental pollution and traffic safety hazards.

DASM turns straw into sustainable building material

Since ancient times, our ancestors knew how to use straw mixed with mud to build houses that effectively protected them from the sun and rain. Although not as solid as houses built with bricks, mortar, and cement, they kept the house cool in the summer and warmer in the winter.

Facing the reality that our country's straw sources are being wasted too much every year, as well as seeing their potential in being recycled into green building materials, the Institute for Acoustics Materials Development and Application collected straw samples and started researching this readily available agricultural by-product.

Initial research results are very promising and as predicted by DASM institute researchers. The research team carried out decomposition, fiber separation, and hot-pressing technology to create tightly bonded straw bales/panels. Depending on the purpose of sound insulation, sound absorption, or thermal insulation, certain chemicals and other building materials will be added in appropriate proportions to enhance the product's effectiveness.

Outstanding characteristics of straw-based materials

Straw-based materials have a high sound absorption coefficient and very good sound absorption

Scientists tested and measured the sound absorption capacity of a 56mm thick pressed straw fiber sample. The results were quite surprising because the obtained sound absorption coefficient was very high, close to 1, almost absolute. This coefficient is currently equal to the sound absorption coefficient of mineral wool, sonic acoustic panels, and recycled foam.

Sound absorption capacity of the recycled straw material sample with a thickness of 56mm

Recycled straw materials have better sound insulation at the same thickness

Scientists of the DASM institute, after processing the straw fibers, mixed in some other components, including cement to eliminate gaps between the straw fibers, increasing the efficiency of blocking transmitted sound. Measurement results of the 45mm thick sound-insulating straw fiber sample showed good sound insulation performance, in the frequency range from 1000 to 2000Hz, equivalent to the sound insulation capacity of a 100mm thick concrete wall.

Sound insulation capacity of the straw fiber material with a thickness of 45mm

According to the initial research results of the DASM institute, it can be seen that recycled straw material is a potential sound insulation material of the future, which can effectively replace old types of sound insulation materials.

Recycled straw materials have a low thermal transmittance and good thermal insulation

Not only having sound insulation and sound absorption capabilities, recycled straw materials also have effective thermal insulation effects.

Research also shows that straw has a thermal conductivity of 0.036 W / m • K, while fiberglass has a thermal conductivity of 0.04 W / m • K and mineral wool is 0.045.

Not only having a lower thermal conductivity than mineral wool and fiberglass, but it is also even worse than wood and brick. Specifically, straw material conducts heat 4 times less than wood and 8 times less than brick. This means that the thermal insulation capacity of straw is better. Houses using thermal insulation materials made from straw components will maintain a more stable temperature level, and indoor temperatures will change less according to external weather.

In fact, in other countries around the world, straw thermal insulation materials are currently used very popularly in residential buildings as well as in high-rise building construction. This thermal insulation solution is currently favored in Russia and countries in cold snowy climate regions.

Recycled straw materials are lightweight, reducing the load on structural construction

Also according to research and calculation, scientists of the DASM institute concluded that material panels made from straw not only have good sound insulation, sound absorption, and thermal insulation efficiency, but importantly, they are very light in weight, much lighter than most building materials with the same properties.

Straw has a high porosity structure of up to 99%, so its density is low, and its weight is ultra-light. Therefore, when combined with other materials to make sound and thermal insulation materials, their weight is still much lighter than common traditional sound and thermal insulation materials such as: bricks, tiles, cement, concrete, stone, etc. For example, at the same thickness of 100mm, the weight of a wall using straw material will only be 1/10 the weight of a concrete wall.

Recycled straw materials are safe for health and protect the environment

With a composition mainly of straw from 100% natural sources, the sound insulation and thermal insulation products made from straw are proven safe for users, do not emit toxic gases during use, and do not cause uncomfortable allergies like some current building materials.

And of course, with the high biodegradability of straw, this is also an eco-friendly material, reducing negative impacts on the ecosystem and contributing to promoting a more sustainable ecosystem development.

In the future, besides recycling straw into green building materials, the institute aims to expand research to other readily available agricultural by-products in our country such as bagasse and coconut fiber.