Optimizing the Mechanical Properties of Cement Composite Boards Reinforced with Cellulose Pulp and Bamboo Fibers for Building Applications in Low-Cost Housing Estates

Our plain-English summary of Optimizing the Mechanical Properties of Cement Composite Boards Reinforced with Cellulose Pulp and Bamboo Fibers for Building Applications in Low-Cost Housing Estates, by A.S. Taiwo, D.S. Ayre, M. Khorami, et al (Materials, 2024).

The study

• Authors: A.S. Taiwo, D.S. Ayre, M. Khorami, S.S. Rahatekar
• Journal: Materials
• Published: 2024;17(3)
• Read it: PubMed · Publisher · Free full text

Abstract

Africa is the third-richest continent in the world in terms of bamboo species. Despite these laudable natural resources, most African countries still use asbestos cement board as one of their major building materials. This is chiefly due to the high cost of equipment and technologies associated with non-asbestos-fiber cement board production. The current research seeks to underscore the possibility of utilizing these massive continent resources for non-asbestos-fiber cement board production by employing the existing production process in the asbestos cement industries via an innovatively developed laboratory-simulated Hatschek process. Non-asbestos-fiber cement boards incorporating kraft and bamboo fibers were successfully produced in the laboratory using this innovative method based on Hatschek technology, with natural fibre addition in the range of 2-6 wt.%. Experimental results revealed that the Flexural strength and deflection of the board improved significantly, producing optimum values of 10.41 MPa and 2.0 mm, respectively for composite board reinforced with 10 wt.% and 6 wt.% of kraft pulp and bamboo fibers, respectively. The SEM morphology of the fractured surfaces revealed the mode of composite fracture as well as good interaction at the fiber-matrix interface. Overall, the mechanical properties of the developed composite boards satisfy the minimum requirements of relevant standards based on fiber cement flat sheets and can be employed for internal building applications in low-cost housing estates in developing countries. The outcome of this research indicates that the current industrial production process based on Hatschek technology can be employed for non-asbestos-fiber cement board production using the studied natural fiber.

In plain English

This laboratory study tested building material, not people or health. The authors made small asbestos-free cement boards using pulp from recycled cardboard (kraft pulp) and chopped bamboo fiber, with a lab copy of the Hatschek process used in asbestos cement factories. They measured bending (flexural) strength after 7 and 14 days of curing, along with water absorption, swelling with humidity, and density. Strength rose as kraft pulp increased up to 10 wt.%. Those boards reached 7.68 MPa and 7.78 MPa at 7 and 14 days, against 4.64 MPa and 5.45 MPa for the control boards without fiber. Strength then fell at higher kraft pulp amounts. Adding 6 wt.% bamboo to the 10 wt.% kraft board gave the highest strength, 10.41 MPa, which was 34% above the kraft-only board. It also bent about 2 mm before peak stress, compared with about 0.6 mm for the kraft-only board. More bamboo raised water absorption, from 13.4% to 23.85%, and lowered density. The authors concluded the boards may be recommended for interior building use in low-cost housing in developing countries.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory materials-testing experiment: fiber cement boards made with a lab-simulated Hatschek process and tested for mechanical and physical properties
• Who was studied: Laboratory-made cement board specimens (8 mix designs; 10 specimens per mix, 5 tested at 7 days and 5 at 14 days of curing), made at Cranfield University, UK. No people were studied.
• Exposure: No asbestos was tested. Boards contained Ordinary Portland Cement with kraft pulp from recycled cardboard (5 to 20 wt.%) and, in a second stage, 10 wt.% kraft pulp plus 2, 4 or 6 wt.% chopped bamboo fiber (4 to 6 mm long).
• Main results:
  • Control boards with no fiber had flexural strengths of 4.64 MPa at 7 days and 5.45 MPa at 14 days. Boards with 5% kraft pulp (K5) were 34% and 37% stronger than the control.
  • Boards with 10% kraft pulp (K10) had flexural strengths of 7.68 MPa at 7 days and 7.78 MPa at 14 days, increases of 65% and 43% over the control. Strength rose with kraft pulp up to 10 wt.% and dropped at higher contents.
  • Adding bamboo fiber to the 10% kraft board raised flexural strength to an optimum of 10.41 MPa at 6 wt.% bamboo, a 34% improvement over the kraft-only board (K10). At the lowest bamboo content the improvement was only 10%.
  • The board with 6 wt.% bamboo (K10-BB6) peaked at about 2 mm deflection, compared with approximately 0.6 mm for the kraft-only board (K10), after 14 days of curing.
  • Water absorption was lowest for the kraft-only board (13.4%) and highest for the 6 wt.% bamboo board (23.85%). It rose as bamboo content increased.
  • Boards with 2, 4 and 6 wt.% bamboo had densities of 1.62, 1.52 and 1.27 g/cm3. These were 4%, 10% and 32% lower than the kraft-only board.
  • Change in length with humidity (moisture movement) increased with bamboo content. The difference between the 2 wt.% and 6 wt.% bamboo boards was about 0.27%.
  • Heat testing (thermogravimetric analysis) showed the bamboo fiber had lost approximately 74% of its weight at about 350 degrees C. The authors interpreted the results as showing the fiber would not degrade during cement hydration.
  • Electron microscope images of broken specimens showed failure by a combination of fiber fracture and fiber pull-out.
• The authors' conclusion: The authors concluded that the bamboo-fiber-reinforced boards had flexural strength and toughness acceptable for fiber cement flat sheets under relevant standards. They said the boards may be recommended for internal building applications in low-cost housing estates in developing countries.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement.

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