Investigation of Lignite-Based Bottom Ash for Structural Concrete

Abstract

A pilot study was undertaken on the use of lignite-based bottom ash as a fine aggregate in structural grade concrete. Bottom ash is combined with portland cement, crushed limestone coarse aggregate, and water to produce concretes with a uniform slump of 100 mm (4 ± 1/4 in.). Four different mixes with cement contents ranging from 297 to 475 kg/m 3 (500 to 800 lb/yd 3 ) are utilized. The bottom ash concretes are studied for fresh properties, hardened characteristics, and long-term durability. The engineering characteristics of mixtures made with bottom ash are compared with those of conventional concretes in order to evaluate the effectiveness and suitability of bottom ash as a viable fine aggregate in portland cement-based mixtures. Laboratory test results conclude that the inclusion of bottom ash increases the demand for mixing water in obtaining the required workability. As a consequence, both fresh and hardened properties are impacted, particularly for mixtures of low cement content. When a water-reducing admixture is used, the engineering properties of bottom ash concretes are similar, and in most cases superior, to those of control concretes.