The global availability and abundance of clay soil and limestone have recently driven research for their combined use as supplementary cementitious material (SCMs). In tropical regions, laterite (which has similar chemical signature to clay) naturally abounds in larger quantities and can potentially be used in place of clay soil as SCM. This is the focus of this study which experimentally evaluates the comparative performance of concrete made from limestone calcined clay, limestone calcined laterite and calcined laterite as supplementary cementitious materials by simple test methods. The replacement of the Portland cement with these SCMs was up to 45% to achieve low-carbon cementitious materials. The cementitious materials were characterised and four concrete mixes (100% ordinary Portland cement; 15-30-55% of limestone-calcined clay-Portland cement; 30–70% of calcined laterite-Portland cement; and 15-30-55% of limestone-calcined laterite-Portland cement) were formulated to showcase their performance in terms of workability, strength, and durability. The possibility of a differing influence of varied water-to-binder ratio on the clay and laterite SCMs was also examined. The results show no significant difference between the performance of the laterite-based and clay-based blended cement concrete. It was concluded that laterite can be interchangeably used in place of clay in limestone calcined clay cements (LC3), especially in tropical regions where laterite is in abundance as much as or more than clay. Further investigation is recommended for long term performance evaluation.

Comparative performance of limestone calcined clay and limestone calcined laterite blended cement concrete

Calcium-based binders, such as ordinary Portland cement (OPC) and lime (CaO), are the most common artificial cementitious materials used worldwide for concrete and soil improvement. However, using cement and lime has become one of the main concerns for engineers because they negatively affect the environment and economy, prompting research into alternative materials. The energy consumption involved in producing cementitious materials is high, and the subsequent CO2 emissions account for 8% of the total CO2 emissions. In recent years, an investigation into cement concrete’s sustainable and low-carbon characteristics has become the industry’s focus, achieved by using supplementary cementitious materials. This paper aims to review the problems and challenges encountered when using cement and lime. Calcined clay (natural pozzolana) has been used as a possible supplement or partial substitute to produce low-carbon cement or lime from 2012–2022. These materials can improve the concrete mixture’s performance, durability, and sustainability. Calcined clay has been utilized widely in concrete mixtures because it produces a low-carbon cement-based material. Owing to the large amount of calcined clay used, the clinker content of cement can be lowered by as much as 50% compared with traditional OPC. It helps conserve the limestone resources used in cement manufacture and helps reduce the carbon footprint associated with the cement industry. Its application is gradually growing in places such as Latin America and South Asia.

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Calcium-Based Binders in Concrete or Soil Stabilization: Challenges, Problems, and Calcined Clay as Partial Replacement to Produce Low-Carbon Cement

Reinforced concrete structures have a limited lifespan and need repair during their use. The success of the repair depends on the characteristics of the repair material and repair methods. Repair by ready-made mortar is extensively used, although these mortars are expensive and often incorporate small volumes of synthetic fibres. This article aims to develop a durable repair mortar with low environmental impact based on 1% alkaline or hydrothermal treated or untreated date palm fibers (DP) of 10 and 30 mm in length combined with 15% of slag or natural pozzolan as cement replacement material. Compressive and flexural strength, bond strength by slant shear and pull-off tests, total shrinkage, and thermal conductivity were investigated. A reduction in shrinkage and thermal conductivity were observed and an increase in bond strength following the addition of treated PD fibers. Graphical abstract

Performance of local date palm fibers in cementitious materials

The use of natural calcined clay as supplementary cementitious materials as a replacement of a portion of cement in concrete is becoming interesting. Although calcined clay is used to improve stren...

Mechanical and durability study of Tunisian calcined clay in lightweight concrete of expanded clay

This work investigates the influence of date palm and sisal fibers on the mechanical and physical behavior of lightweight concrete based on expanded clay aggregates. The choice of these fibers types is aimed at the recovery of agricultural waste in Tunisia. Their exploitation serves to improve the mechanical and physical properties of a new material dedicated to filling and insulation in buildings. In this context, series of tests were carried out using untreated short fibers in lightweight concrete. The evaluation of the mechanical and physical behavior of the material was obtained by determining the compressive strength, bending strength and thermal conductivity. The results obtained showed the influence of the fibers volume fraction. For mechanical behavior, the optimum of fibers volume fraction was estimated at 1% for lightweight concrete with date palm and sisal fibers. The thermal conductivity is inversely proportional to the fibers volume fraction, which justifies the use of this composite as a filling and insulation material.

Nawel Salem

Papers

Mechanical and durability study of Tunisian calcined clay in lightweight concrete of expanded clay

Optimization of the Mechanical and Physical Properties of Lightweight Concrete Reinforced with Date Palm and Sisal Fibers