Effects of nano-clay particles on the short-term properties of self-compacting concrete

Abstract

The properties of self-compacting concrete (SCC) can be manipulated by the addition of nano-montmorillonite (NMMT) clays. This paper presents the results of an experimental investigation on incorporating small dosages of NMMT clays (.25, .50, .75 and 1.00% addition by mass of total cementitious material) into SCC. Tests were conducted on fresh and hardened specimens to measure workability (by slump flow, V-funnel and L-box), mechanical (by compressive and splitting tensile strengths), durability (electrical resistivity and water penetration) and microstructural (X-ray diffraction and scanning electron microscopy) properties of control and NMMT-reinforced SCCs. The results showed that the addition of .5% NMMT resulted in the highest compressive strength; however, a mixture with .75% NMMT had the highest splitting tensile strength among mixtures at curing ages of 7, 28 and 56 days. Nevertheless, durability of specimens was improved by the addition of NMMT up to 1%. X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests indicated that NMMT particles can possess pozzolanic activity and pore-filling ability, which refined the microstructure of SCC mixtures. Based on the microstructural test results, lower enhancement of mechanical properties of SCC specimens at higher addition dosages could be related to the lower NMMT efficiency due to higher risks of NMMT particles agglomeration.