[01] Bruce Roy Thulane Vilane, Department of Agricultural and Biosystems Engineering, Faculty of Agriculture, University of Swaziland, Luyengo Campus, Swaziland. [02] Thandeka Lucia Dlamini, Department of Agricultural and Biosystems Engineering Student, Faculty of Agriculture, University of Swaziland, Luyengo Campus, Swaziland.

Concrete quarry dust blocks (CQDB) are manufactured from a mixture of cement: sand: quarry dust. A descriptive study using structured questionnaires and Laboratory test procedures was conducted to determine the structural integrity of CQDB in Matsapha, Swaziland. The companies; [CM concrete (CM), Nkwality Bricks and Pavers (N), Roots (R), Dlamini Block Yard (D), Santos Block Yard (S) and Toepfer and Sons (T and S)] that used quarry dust to produce concrete blocks were studied. Five load bearing CQDB were purchased from each company. A thin film of plaster of Paris was applied prior to load testing using a compression load testing machine at a rate of 100 kN per minute. The results reflected that CM concrete, N, D, Roots, Toepfer and Sons as well as Santos produced CQDB with compressive strengths of 5.55 N/mm², 3.39 N/mm², 1.68 N/mm², 1.24 N/mm², 3.02 N/mm², and 1.92 N/mm², respectively. Only CM concrete manufactured CQDB that met the standard 4.0 N/mm² mean compressive strength of 5 units. The CQDB manufactured by the other five companies were even below the standard 3.0 N/mm² unit block compressive strength. The CQDB were fabricated using the mixtures; 1:2:3, 1:1:4, and 1:3:2. The mix 1:2:3 was used by CM concrete, D and N. Roots, T and S, used the mix 1:1:4 and S used the 1:3:2 mix. All the CQDB companies in Matsapha used the curing period of 7 days except for D and R which used curing periods of 3 and 4 days, respectively. It was concluded that the structural integrity of the CQDB manufactured in Matsapha was not of acceptable quality. This was evident from the compressive strengths attained by the CQDB manufactured. CM concrete was the only company in Matsapha that manufactured CQDB that met the 4.0 N/mm² mean compressive strength of five (5) concrete block units enshrined in the South African National Standards (SANS 1215).

Structural Integrity, Quarry Dust, Concrete Blocks, Matsapha, Swaziland

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