Effect of Curing Time on the Compressive Strength of Agrostone Building material with water hyacinth, bagasse and grass bio fillers- a comparative study
Introduction
Compressive Strength of Agrostone Building Material is a critical metric for evaluating the viability of low-cost, eco-friendly construction alternatives in developing economies. As urbanization accelerates in Sub-Saharan Africa, the demand for affordable housing solutions has outpaced the supply of conventional building materials.
This disparity has driven researchers to investigate agricultural waste products as viable bio-fillers in cementitious composites.
A recent study published in the Journal of Engineering Science and Technology provides a detailed comparative analysis of Agrostone panels reinforced with water hyacinth, bagasse, and grass. The research specifically examines how curing time influences the structural integrity of these materials, offering vital insights for engineers, policymakers, and sustainable housing advocates.
Understanding Agrostone and Its Role in Sustainable Construction
Agrostone is a lightweight, eco-friendly building material composed primarily of magnesium oxychloride cement (MOC), also known as Sorel cement or eco-cement. Unlike traditional Portland cement, which is energy-intensive and contributes significantly to global CO2 emissions, MOC requires only 20-40% of the energy for production.
This makes the Compressive Strength of Agrostone Building material not just a measure of durability, but also an indicator of environmental efficiency.
The material is formed by mixing powdered magnesium oxide with a concentrated solution of magnesium chloride. To enhance its properties, the mixture includes fillers for reinforcement. Historically, agricultural and industrial wastes such as bagasse have been used.
However, the logistical challenges and costs of transporting these materials from distant sources have prompted a search for locally available alternatives.
In Ethiopia, where this study was conducted, water hyacinth infestation in Lake Tana presents both an environmental hazard and a potential resource.
By converting this invasive weed into a bio-filler, the construction industry can address two problems simultaneously: waste disposal and material scarcity.
The study aims to determine if water hyacinth can replace imported bagasse or locally collected grass without compromising the Compressive Strength of Agrostone Building material.
This comparison is essential for establishing standardized protocols for the use of organic waste in structural applications.
Methodology for Testing Compressive Strength of Agrostone Building material
To ensure the reliability of the data, the research adhered to strict experimental standards. Specimens were cast as 50 mm cubes, following the ASTM C109 standard.
Three distinct types of Agrostone were prepared, each utilizing a different bio-filler: Type I used water hyacinth, Type II used bagasse, and Type III used grass. For each type, twenty-four specimens were created, with six specimens tested at intervals of 7, 14, 21, and 28 days of curing.
The preparation of the bio-fillers was meticulous. Water hyacinth was collected from the Blue Nile River, washed, sun-dried for ten days, and then oven-dried at 105°C for eight hours to remove all moisture.
This step is crucial because residual moisture can significantly affect the Compressive Strength of Agrostone Building material. The dried plant matter was then ground into small pieces. Similarly, bagasse was obtained from the Fincha Sugar Factory, and grass was collected and processed using a hammer mill.
The mix design consisted of 85.2% binders, 14% fillers, and 0.8% reinforcement by weight. Fiberglass was added to improve flexural strength. An activated solution containing magnesium chloride, sodium hydroxide, hydrochloric acid, and hydrogen peroxide was used to initiate the chemical reaction.
Notably, the water hyacinth mix required an additional 0.2 liters of activated solution to achieve a texture similar to the other mixes, indicating its higher water absorption capacity.
This variable is a key factor when analyzing the Compressive Strength of Agrostone Building material, as water content directly influences the hydration and hardening process.
Comparative Analysis of Compressive Strength of Agrostone Building material
The core of the study focuses on how the Compressive Strength of Agrostone Building material evolves. The results demonstrated a linear increase in strength for all three bio-filler types as the curing period extended.
At 7 days, the average compressive strength for water hyacinth Agrostone was 5.26 MPa. By day 28, this value had risen to 6.40 MPa. In comparison, bagasse-based Agrostone achieved 7.17 MPa, and grass-based Agrostone reached 9.37 MPa after 28 days.
While bagasse and grass exhibited higher absolute compressive values, the performance of water hyacinth was still significant. The Compressive Strength of Agrostone Building material made from water hyacinth exceeded the 5 MPa requirement for Class AAA hollow concrete blocks as specified by the Ethiopian material code. This finding validates the potential of water hyacinth as a structurally sound alternative.
An interesting observation was the rate of strength gain. Water hyacinth Agrostone attained 82.2% of its full 28-day strength within just 7 days. In contrast, bagasse and grass Agrostone reached only 74.9% and 77.2% of their respective full strengths in the same period.
This rapid initial strength development suggests that the Compressive Strength of Agrostone Building material using water hyacinth allows for faster construction timelines, as panels can be moved to sites sooner without risking structural failure.
Impact of Moisture on Structural Integrity
The study also highlighted the sensitivity of MOC-based materials to moisture. Specimens cured in conditions of higher relative humidity showed slight increases in mass due to water absorption, which correlated with a reduction in binding strength.
When specimens were oven-dried after 28 days, the Compressive Strength of Agrostone Building material increased dramatically. Water hyacinth specimens saw a 40.8% increase, bagasse a 69.3% increase, and grass a 46.7% increase.
This underscores the importance of proper drying protocols in maintaining the intended Compressive Strength of Agrostone Building material in real-world applications.
Economic and Environmental Implications of Agrostone Usage
Beyond technical performance, the economic viability of any building material is paramount. The study conducted a detailed cost analysis comparing Agrostone partition walls to traditional hollow concrete block (HCB) walls.
The production cost of water hyacinth Agrostone was found to be slightly lower than that of bagasse or grass variants, primarily due to the negligible cost of the raw bio-filler. Water hyacinth is an invasive weed that is often removed at a cost; utilizing it as a resource turns a liability into an asset.
When considering the finished wall, including plastering and painting, the cost savings are substantial. The total cost per square meter for a water hyacinth Agrostone wall was approximately $13.99, compared to $21.39 for a comparable HCB wall.
This represents a 53% reduction in cost. Such savings are driven by the lightweight nature of the material, which reduces labor costs for fitting, and the smooth finish of Agrostone, which minimizes the need for extensive plastering.
Therefore, the Compressive Strength of Agrostone Building material is not only sufficient for non-load-bearing partitions but also offers a compelling economic advantage.
From an environmental perspective, the use of water hyacinth helps mitigate the ecological damage caused by its infestation in Lake Tana. By providing a commercial use for the harvested weed, the study supports a circular economy model.
Furthermore, the lower energy requirements for producing MOC compared to Portland cement contribute to a reduced carbon footprint. The Compressive Strength of Agrostone Building material thus serves as a benchmark for sustainable development, balancing structural needs with environmental stewardship.
Specific Strength and Material Efficiency
While absolute compressive strength is important, the strength-to-weight ratio, or specific strength, is a critical criterion for modern construction. Lightweight materials reduce the load on foundations and superstructures, leading further cost savings in structural support.
The study calculated the specific compressive strength for each bio-filler type. Water hyacinth Agrostone exhibited a specific strength of 0.0140, compared to 0.0137 for bagasse and 0.0119 for grass.
This indicates that, despite having lower absolute compressive values, water hyacinth Agrostone is more efficient per unit of mass. The low bulk density of water hyacinth fibers (140 kg/m³) compared to bagasse (405 kg/m³) and grass (340 kg/m³) contributes to this advantage.
For engineers prioritizing lightweight structures, the Compressive Strength of Agrostone Building material made from water hyacinth offers an optimal balance of performance and efficiency. This characteristic makes it particularly suitable for multi-story buildings where reducing dead load is a priority.
Conclusion
The comprehensive analysis presented in the study confirms that water hyacinth is a viable, cost-effective, and eco-friendly bio-filler for Agrostone production. While bagasse and grass provide higher absolute compressive values, the Compressive Strength of Agrostone Building material using water hyacinth meets all relevant structural standards for partition walls.
Its rapid strength gain, superior specific strength, and significant cost reductions make it an attractive option for mass housing projects in Ethiopia and similar contexts.
The findings emphasize the importance of curing time and moisture control in optimizing the Compressive Strength of Agrostone Building material. As the construction industry continues to seek sustainable alternatives to conventional concrete, the integration of agricultural waste like water hyacinth offers a promising path forward.
Future research should focus on long-term durability, thermal conductivity, and fire resistance to further validate the widespread adoption of this innovative material.
Ultimately, the Compressive Strength of Agrostone Building material stands as a testament to the potential of local resources to solve global housing challenges.