Stephen Amiandamhen
Research Scientist
Abstract
This paper presents a comprehensive study on lightweight cement-bonded composites containing pulp sludge (PS). The objective of the study was to evaluate how the incorporation of perlite (a lightweight volcanic glass aggregate) and lime mud (a pulp mill residue) influences composites’ properties including mechanical strength, insulation and fire resistance. Up to 50% of the cement binder was replaced with PS (by mass), and small fractions of cement (5–15%) were replaced with perlite or lime mud. A suite of analytical techniques, material characterization and mechanical tests with digital image correlation (DIC) for strain analysis were employed. X-ray analysis showed that the aggregates influenced the composite properties to a considerable extent due to their particle sizes and ability to form hydrated gels with cement. Adding 5% of perlite or lime mud yields optimal strength without compromising weight reduction whereas higher aggregate content (15%) led to reduced strength. The DIC system provided insights into strain distribution during loading, confirming enhanced toughness from the fibrous PS. The composites were significantly lighter (732–749 kg/m3) and showed about 30% lower thermal conductivity (0.17 W/mK) than pure cement composites (0.25 W/mK). The normal incidence sound absorption of the composites was about 0.3 at mid-high frequencies due to their compact structure. The composites demonstrated potential for use as sustainable, lightweight construction materials with good acoustic and thermal insulation, as well as acceptable load-bearing capacity for non-structural applications based on EN 634-1/-2 requirements for cement-bonded particleboards.
Abstract
Abstract This study assesses the economic feasibility and environmental profile of producing Irvingia-based wood adhesives on a small scale (30 ton/year) in South Africa. A detailed techno-economic analysis was conducted including operating cost estimation and sensitivity analysis of key input variables. The estimated production costs for three adhesive formulations ranged from R157.1/kg – R318.14/kg. The average production cost was R214.62/kg and was below the typical market price of R379/kg for synthetic wood adhesives. Raw materials especially kernels and modifiers were identified as the dominant cost drivers, whereas labour and electricity had minimal impact on unit cost. A carbon footprint assessment (CFA) was performed with cradle-to-gate boundaries to estimate greenhouse gas (GHG) emissions. Two raw material sourcing scenarios were considered. They included adhesive production from kernels and adhesive production directly from whole fruits (including on-site fruit dehulling). The cradle-to-gate CFA indicates that both scenarios have similar GHG emission profiles given equivalent process conditions, with most emissions arising from energy use and chemical additives rather than feedstock transport. A review of mechanical performance from prior studies showed that these bio-based adhesives met industry standard requirements. The results demonstrate that small-scale production of Irvingia adhesives is economically viable and environmentally sustainable, making it a promising alternative to synthetic adhesives for wood composite manufacturing in South Africa.
Authors
Dafni Foti Stephen Amiandamhen Eleni Voulgaridou Elias Voulgaridis Costas Passialis Stergios AdamopoulosAbstract
Abstract This study investigated the incorporation of various waste materials including wastepaper, Tetra Pak, wood chips and scrap tire fluff into flue gas desulfurization (FGD) gypsum and cement mortar matrices to produce sustainable composite materials. Four distinct composite types based on the waste materials were developed and evaluated for selected properties including thermal and acoustic insulation. The proportion of the waste materials was varied between 10 and 40 vol% of the base matrix. The compressive strength of the filled gypsum composites was in the range of 4.17–10.39 N/mm² while the pure gypsum was 11.38 N/mm². The addition of the wastes in gypsum composites reduced compressive strength by about 10% for the best recipe and as large as 60% for the worst combination. However, the measured strength still exceeds the strength of typical gypsum wallboard with a compressive strength of about 3–4 N/mm² for whole-board crushing tests and it is much lower for point loads. The normal-incidence sound absorption coefficient indicated that the waste-filled samples absorbed around 80% of the incident sound energy between 2000 and 3000 Hz, comparable to some commercial acoustic foams. The results highlight the potential of utilising these waste-based composites in environmentally friendly construction applications. Depending on the waste type and matrix used, the results revealed trade-offs between multi-functional performance and sustainability benefits.