Assessing the durability properties of sandcrete blocks incorporating iron filings as fine aggregate

Abstract

The rising costs of construction materials, particularly sandcrete blocks, necessitate the exploration of cost-effective alternatives. This study examines the feasibility of incorporating iron filings (IF), a by-product of metal workshops, into hollow sandcrete block production and assesses their performance under harsh conditions. IF was used to replace 5–20 % of the fine aggregate component in blocks at a step of 5 %, mixed at a 1:8 ratio, and sized at 450mm×150mm×225mm. The study evaluated the impact of acidic exposure on the density, sorptivity, and compressive strength of these blocks, as well as their sensitivity to elevated temperatures. The results showed that IF blocks had significantly lower density than non-IF blocks, especially those cured with H₂SO₄. For instance, blocks with 15 % IF and cured in 0.3 mol/dm³ H₂SO₄ had a 13.9 % reduction in density. Despite higher acid concentrations, IF samples demonstrated better sorptivity, absorbing water more slowly than non-IF samples. However, exposure to acidic media reduced compressive strength by 1.9 %–47.8 % for HNO₃ exposure and 0.5 %–42.4 % for H₂SO₄ exposure. None of the acid-exposed blocks met the minimum standards for load-bearing (2.5 MPa) or non-load-bearing walls (2.0 MPa) as per NIS standards. Furthermore, the sensitivity of IF sandcrete blocks to changes in compressive strength under elevated temperatures decreased by almost half, from 0.026 to 0.014 MPa/°C, as the curing period increased from 7 to 28 days. Blocks with 5–15 % IF showed improved compressive strength at temperatures below 150 °C, but strength declined sharply beyond this temperature. By utilising IF, a readily available waste material, the implications of the study are significant for promoting a circular economy in the construction industry. However, the performance of the blocks against durability concerns needs to be improved further before integrating such waste materials into developing sustainable and resilient construction materials

Keywords

• Building
• Temperature sensitivity
• Sorptivity
• Waste
• Circular economy