Enhancement of the Properties of Libyan Concrete through the Incorporation of Natural Additives Derived from Palm Waste or Local Limestone: A Comparative Data-Driven Assessment

Abstract

The concrete manufactured in Libya is subject to hot-dry weather conditions, variability in the quality of aggregates used, and quality control, whereas the agricultural waste from date palm (Phoenix dactylifera L.) and common carbonate rocks can be considered underutilized sources of additives to concrete. This work provides a comparative and evidence-based analysis of natural additives based on palm waste (fibers and ash) and limestone (powder) for improving the characteristics of Libyan concrete. The quantitative data were retrieved from nineteen scientific publications and official sources, harmonized and analyzed by means of relative change and trend analysis. The field data from 20 Libyan projects demonstrated a coefficient of variation in strength of 5.58-25.19%. When used in date palm fiber concrete, increasing the share of fibers from 1% to 3% decreased 28-day compressive strength by 16.6% but increased flexural strength by 11.4%, whereas water absorption increased by 24.5%. Partial substitution of cement (5-10%) by silica fume recovered 4.3-16.7% of the compressive strength lost due to fibers and decreased water absorption by up to 24.8%. As for palm ash and limestone powder as cement substitutes, 10% became the most persistent optimal level: Ashes from date palm seeds at 10% were 31.5 N/mm² compared to 31 N/mm² for the control at 56 days, while Libyan fronds ashes at 10% increased mortar strength at 28 days by 31.3%. Additionally, 10% limestone substitution was competitive, while above this percentage diminished carbonation resistance. Altogether, it can be concluded that waste products from palms should preferably be used in low dosage in the form of fiber or ash, and local limestone as filler at a 10% substitution rate.