EVALUATION OF THE QUALITY OF RIVER SAND ON PROPERTIES OF CONCRETE IN THE CONTEXT OF ADDIS ABABA, ETHIOPIA

TESHAGER DEMISSIE, Dr. Belachew Asteray
2019
River sand/natural fine aggregate used in concrete production may contain excessive silt and clay as well as organic impurities. These impurities affect the overall performance of the concrete product. The objective of this research is to evaluate the level of silt/clay contents, organic impurities present in sand being supplied to Addis Ababa construction industry and to assess the effect of these impurities on workability and compressive strength through experimental investigation. Based on
more » ... igation. Based on the methodology for sampling, nine samples of sand were collected from two main sand local markets found at Akaki and Alamgena. Visual inspections, index property, impurities, workability, and compressive strength tests were conducted on nine sand samples. Grain size analysis test results revealed that all local sand samples cannot fulfill the requirement set by ASTM 117 standard as they are collected directly from their natural places. The index properties test reveals that sand used for the study qualifies the aggregate requirements. According to ASTM C40, the organic impurity test result did not present in numerical value therefore difficult to determine their effect quantitatively. But, for further investigation, the result of the NaOH solution was divided into three and leveled accordingly. From each sand sample, nine concrete cubes with 150 mm × 150 mm × 150 mm size were cast using concrete mix ratio 1:2:2.5 for the strength of 30 MPa that can be used (mostly) in moderate height building (cement: sand: coarse aggregates: water). To determine variation in strength as regards the different percentages of impurities present in fine aggregates samples. Concrete cubes produced from each sand samples with the same coarse aggregates, cement, and water were subjected to compressive strength tests at the age of 3, 7 and 28 days. It was discovered that the higher the percentage of silt/clay content in the sand samples, the higher the reduction effect on the cube strength and the more the fine content reduction on workability. Th [...]
doi:10.20372/nadre/4149 fatcat:5aeaxmsi35fjjcmoltal7fdmdi