Balteh Mohammed, Ebenehi Ibrahim Yakubu, Shuaibu Nuru Mamman, Muhammad Nda, Adamu Abdullahi Ayni, Mukaila Zakari, Bello Kabir
Anotace:
Concrete is an extensively used construction material due to its versatility, strength, durability, and ease in making various forms and shapes. The use of substandard materials, deficient quality concrete has been identified in the literature as the leading cause of building collapse in Nigeria. Aggregates strongly affect the concrete’s fresh and hardened properties, mixture proportions, and economy. More than 1/3 of the volume of concrete is occupied by the coarse aggregate, and any changes in rough aggregate type could affect its strength and fracture properties. This study examined the impact of coarse aggregates on the mechanical properties of concrete. Selected aggregates which are granite (igneous rock), schist (metamorphic rock), and sandstone (sedimentary rock), were used in this study. Aggregate Impact value and water absorption test were carried out for each of the aggregates used. A slump test was conducted on the fresh mixture for granite, schist, and coarse sandstone aggregates with river sand (fine aggregate) using a water-cement ratio of 0.50; it was observed that granite has a slump value of 35 mm, schist 28 mm, and sandstone 25 mm. Nominal mix (1:2:4) was adopted, and mix compositions were calculated using the absolute volume method. Twelve cubes (100x100 mm) and twelve cylinders (100x300 mm) were cast for each type of coarse aggregate. The specimens were cured by submersion. Three of the models were tested for 7, 14, 21, and 28 days to determine their compressive and splitting tensile strengths. Granite was found to have the highest average compressive strength of 16.00 N/mm2 with an average density of 2575 kg/m3, compressive strength of schist was 15.17N/mm2 with an average density of 2520 kg/m3, while sandstone has the lowest average compressive strength of 12.33 N/mm2 with an average density of 2500 kg/m3. Granite was found to have the highest moderate splitting tensile strength of 1.31 N/mm2 with an average density of 4266.67 kg/m3, breaking tensile strength of schist was 0.99 N/mm2 with an average density of 4256.67 kg/m3.
In contrast, sandstone has the lowest average split tensile strength of 0.67 N/mm2 with an average density of 4241.67 kg/m3. Densities and stability of the individual aggregates accounted for the variation in the concrete forces because of differences in properties and strength. In conclusion, the effect of coarse aggregate on the properties of concrete was identified, which will inform site concrete production of the suitability of aggregate selection in concrete work.
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