Some Properties of RCC Containing Silica Sand Powder Exposed to MgSo₄ Solution

Roller compacted concrete (RCC) is a special type of concrete with zero or even negative slump consistency. This work has been targeted to produce and investigate the durability of an RCC mix suitable for roads paving with better engineering properties. Different RCC mixes have been prepared using micro natural silica sand powder (SSP) as a partial substitution by weight of sulfate resistant Portland cement, i.e., [0% (M-R), 5% (M-SSP5), 10% (M-SSP10), and 20% (M-SSP20)]. Additionally, M-sand, crushed stone (NMSA of 19.0 mm), filler, and water were used. Materials have been proportioned according to ASTM D1557. Slabs prepared and cast in molds with dimensions of 38×38×10cm using a vibrating table and manually operated human-made rolling device. Sawing was made after 28 days of normal curing to obtain cubes of 10×10×10cm and prisms of 10×10×38cm used for different tests. Continuous full immersion in 5% MgSO₄ solution at a temperature of (23±2)°C for 60 and 120 days was implemented to investigate the durability of RCC specimens. The compressive strength (f'cu) of M-SSP5 increased by 7.35% and 7.14%, and the flexural strength (fr) increased by 32.1% and 33.67%, after 60 and 120 days of exposure, respectively, compared to the control mix.