• Impact of vibration time on compressive strength of hardened sandcrete building blocks

      Omoregie, Alohan; University of Bolton (Multidisciplinary Digital Publishing Institute (MDPI), 2012-05-09)
      The majority of the sandcrete blocks used in the Nigerian building industry fall short of the minimum specification standards. There is evidence to suggest a wide variation in compressive strength from one block manufacturer to another and also within block samples from a single source. This problem has been attributed to poor quality control and substandard constituent materials. Also very alarming is the ignorance surrounding the usage and engineering properties of some of the widely used fine aggregate deposits. As a way forward, this paper aims to re-establish the impact of vibration time in sandcrete block production using six fine aggregate deposits found within Benin City (Midwestern Nigeria) and their various pair combinations. Some of the basic properties like silt content, grading parameters—co-efficient of uniformity (Cu), curvature co-efficient (Cc) and the fineness modulus (Fm)—of these fine aggregates were established by laboratory means. In addition, the wet and dry compressive strength of these sandcrete blocks made from these sands were established. A total of 1,080 block samples produced under very controlled conditions were used in this investigation. It was revealed that the utility value of sand can be improved when the weaker and commonly used sands were combined with those that are better, more expensive and less frequently used at different vibration periods and ratios. Findings further revealed that sand types and the sand combination approach adopted were very significant to grading parameters and strength; at a much higher vibration time the compressive strength and durability properties were also considerably improved
    • The influence of vibration time and sand type on the compressive strength of sandcrete hollow blocks

      Alutu, Okey Edwin; Omoregie, Alohan; University of Benin (Trans Tech Publications, 2009-02-20)
      The purpose of this study is to see if varying the vibration time and sand type during moulding of blocks would affect the strength of the blocks. To this end, seven types of sands: Okhuahie and Ovia river sands; Okhuahie, Ovia, Ikpoba flood and Okhoro erosion sands were collected for the study. A total of 315 blocks each in 150mm and 225mm sizes with cement to sand ratios of 1:6 were made using the seven brands of sand. The blocks were vibrated for 10, 15, 20, 25, and 30 seconds and tested for compressive strength at 7 days, 14 days and 28 days respectively. The result showed that the relationship between compressive strength of the blocks and the vibration time for various sand types was linear up to vibration time of 30 secs. The sand type also influenced the strength of the blocks as Okhuahie river sand gave the highest compressive strength followed by Ovia river sand and the least was Okhoro erosion sand. At least 52% increase in compressive strength of 150mm and 225mm sandcrete blocks were achieved by raising the vibration time from 15 seconds to 25 seconds in the seven types of sand and 100% increase was achieved by raising the vibration time from 15 to 30 seconds.