Technical experts in construction industries are trying to improve the quality, ease of using materials in different forms, and increasing structure performance. However, in the changing cost of each item, quality of works could be sacrificed. In Ethiopia, the practice of using alternative ingredients to produce materials was observed weak in some scenarios. It was because ignoring the right procedures to perform the required material requirements for construction materials. It is known that Ambo area has a scarcity of natural sand or rivers sand which can be extracted from the river bed. Notably, if available, the quality is not good due to the presence of silt and clay. Once it used, it adversely affects the structural integrity of concrete structures. The primary objective of the research is to evaluate the suitability of Ambo Sandstone Fine Aggregate (ASFA) as an alternative replacement of river sand in normal concrete production. Samples extracted from Senkele and Aleltu quarry sites of Ambo Area. Results showed that fine aggregates from Senkele quarry site indicated 14.28% silt content, while from the Aleltu quarry site indicated 12.28% silt content, all of which exceeded 6% based on Ethiopian Standard Specification. It means the samples must be rejected or appropriately washed before use as a part of a concrete mix. After performing the procedure to remove silt content, it found out that the silt content reduced to 5.3%, less than the allowable maximum of 6%. Hence, Ambo Sandstone Fine Aggregates (ASFA) are suitable for concrete mix production and strength determination. There were nine samples of concrete cubes prepared and tested at 7 th , 14 th , and 28 th days for concrete compressive strength with a mix ratio of 1:2:3 and water to cement ratio of 0.50. Based on the laboratory test results with full replacement of river sand by Ambo Sandstone Fine Aggregate (ASFA), the mean compressive strengths at 7 th day was 16.61 MPa, while at the 14 th day was 19.62MPa, and at 28 th day was 25.59 MPa. It means at 28 th day; it satisfied the minimum requirement for C-25 grade concrete. Likewise, the cost of production of the fine aggregate of the Ambo Sandstone quarry site is 140 ETB per cubic meter, while the price of river sand from Legeher Market is 300 ETB-400 ETB per cubic meter. Therefore, Ambo Sandstone Fine Aggregate (ASFA) is cheaper than the river sand. However, it must be given emphasis that the Ambo Sandstone Fine Aggregates must wash thoroughly before use in construction projects.
Purpose Small and medium contractors (SMCs) play a significant role in socioeconomic development. Their strong links with other sectors of the economy have a multiplier effect on any country’s growth. However, the construction business, especially for SMCs, is not an easy business as several roadblocks affect their sustenance. This study aims to examine the factors affecting the sustainable competency of SMCs emerging from the business environment in which the Ethiopian construction industry (CI) operates. Design/methodology/approach A literature review was conducted to identify 39 factors arising from five core sources (i.e. government policies, regulatory frameworks, industry networks, competitive bidding culture and construction technology and innovation). A questionnaire survey was conducted to gather industry stakeholders’ perceptions of the identified factors, and the results were analyzed using descriptive statistics. Findings Findings indicate 37 significant factors affecting sustainable competency arising from five sources, and the top factors from their respective sources were unfavorable financial policy; unfavorable economic regulatory framework; lack of trust between parties in the industry; inability of SMCs to compete with bigger construction companies; and poor linkages between CI and research and development institutions. Furthermore, factor analysis identified 12 components, and the top ones were competition and uncertainties in the supply chain; unsuitable bidding environment; and ineffective industry networks. Originality/value The findings will contribute to the body of knowledge on the factors affecting the sustainable competency of SMCs in the Ethiopian CI. They also indicate priority areas of competitiveness improvement and have implications for decision-makers.
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