Coconut shell: From waste to the best by its role in producing high-quality special concrete

In practice, durable structural lightweight concrete (LWC) can be produced using a type of lightweight aggregate (LWA). Selecting a suitable LWA is challenging in producing this special concrete. The reason is that, although artificial LWAs are commonly used, concerns regarding cost and environmental impacts arise. An alternative to artificial LWAs is the use of industrial wastes, particularly those from the agricultural sector. Among these wastes, coconut shell (CS) has been introduced as a suitable alternative. This study aims to investigate the suitability of CS, as a coarse LWA, in producing high-strength LWA concrete (HSLWAC), which is a major research gap in this field. In normal weight concrete, the conventional coarse aggregate was substituted with CS up to 100 % with an interval of 25 %. Results revealed that an HSLWAC with good workability and a 28-day compressive strength of 50–55 MPa with an equivalent dry density of 1940 – 2000 kg/m 3 was prepared using CS aggregates. In a 100 % replacement level, an LWAC with a 1-day compressive strength of approximately 19 MPa, which is considered a high-early strength concrete, could also be produced. In addition, analysis of the mechanical and durability properties of these special concretes with different CS aggregate contents revealed that this agricultural waste could be considered a high-quality LWA for producing high-strength and durable LWAC. • CS is a high-quality lightweight aggregate to produce high-strength LWAC. • High-strength CS-LWAC with 28-day compressive strength of 50–55 MPa was produced. • Properties of CS concrete are similar to common artificial type of LWAs. • Concrete containing up to 70 % CS is suitable for rigid pavements. • CS concrete has equivalent or better chemical resistance than NWC if well-designed.