MIX DESIGN AND PROPORTIONAL REQUIREMENTS FOR THE PRODUCTION OF C30/37 INTERLOCKING CONCRETE TILES

The inadequate application of standard methods for the design and production of interlocking concrete tiles can result in poor-quality tiles and premature pavement failure. This study investigated suitable concrete mix proportions for producing interlocking concrete tiles with a target characteristic strength of 30 N/mm². River sand was used as the fine aggregate and 10 mm granite chippings as the coarse aggregate. The fine aggregate was within Zone 2 and had a specific gravity of 2.66, while the coarse aggregate had a specific gravity of 2.71. Three trial mixes were developed using SCALE 149 software. The cement:water:fine aggregate:coarse aggregate proportions were 275:160:790:1240 for Mix 1, 290:170:780:1225 for Mix 2, and 320:190:760:1195 for Mix 3. Five specimens were produced for each mix and cured for 28 days before compressive-strength testing. The mean strengths were 37.88, 38.52 and 36.26 N/mm² for Mixes 1, 2 and 3, respectively. Sample standard deviations were 2.747, 2.762 and 3.866 N/mm², respectively. Using the characteristic-strength relationship adopted in this study, fck = x̄ − 1.64s, the corresponding characteristic strengths were 33.37, 33.99 and 29.92 N/mm². Mix 2 produced the highest strength, while Mix 1 provided a lower-cement-content alternative that still exceeded the 30 N/mm² target. Mix 3 was marginally below the target based on the recalculated characteristic strength. The results indicate that Mix 2 is preferable where compressive strength is the primary criterion, whereas Mix 1 warrants consideration where reduced cement content is prioritized.