Effect of sand fineness modulus on SCC and SCLC properties

Abstract

Due to the advantageous characteristics of self-compacting concrete (SCC) and self-compacting lightweight concrete (SCLC), the advancement of the SCC is considered a remarkable engineering feat. Fine aggregate is one of the main parameters of SCC; however, its effect on SCC and SCLC properties is somewhat restricted due to the limited extent of in-depth research conducted in this field. To investigate the effect of changes in sand fineness modulus (FM) on the fresh and hardened properties of SCC and SCLC, an experimental investigation with twelve mixtures was designed. Two series of mixtures were used, each with two coarse aggregate types: Light Expanded Clay Aggregate (LECA) and natural gravel. Each series included different sand FM (2.3, 2.7, and 3.1), with the incorporation of 7% micro-silica (MS) as a cement substitute in some designs. The fresh properties of the concrete were evaluated through tests such as Slump Flow, V-Funnel, U-box, L-Box, and J-Ring, in addition to the Static Segregation Column test. For evaluating the hardened properties, 192 specimens were tested, including compressive, tensile, and flexural specimens. Moreover, fracture energy was also investigated. As the sand FM increased, it was expected that the fresh properties of concrete might decrease due to coarser aggregate volume, and the hardened properties would improve under these conditions. However, the results showed that increasing the sand FM improved the fresh and hardened properties of SCC and SCLC. By increasing the sand FM, the flowability, filling ability, and passing ability of both concrete improved, but on the other hand, elevating the sand FM reduced the segregation resistance of the mixes. In contrast, the hardened properties exhibited contrasting outcomes with increasing the sand FM. Increasing the sand FM improved the compressive strength by about 20% in both concrete types.