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This paper aims to study the effect of Carbon Fiber Filament (CFF) with different ratios and lengths on the physical and mechanical properties of cement mortar. An experimental program included 3 cm fixed length of CFF with 0, 0.25, 0.5, 0.75, and 1% different ratios by weight of cement addition were used in cement mortar cubes. Another experimental program of 0.5% CFF ratio with 1, 2, 3, 4, and 5 cm different lengths by weight of cement addition was used in cement mortar prisms. The physical and mechanical properties of cement mortar containing CFF were experimentally investigated at 7 and 28 days of curing. Workability, by means of flow table test, were measured. Density is conducted for cubes and prisms at the age of 28 days. At ages of 7 and 28 days, compressive and flexural strengths were studied. The study showed a reduction in workability with the increase of CFF ratios and lengths by 0.0 to 2.7% and by 0.9 to 5.4% respectively. Moreover, an improvement in density, compressive, and flexural strengths was observed. At ages of 7 and 28 days, the results showed that compressive strength increased by 33 and 31% respectively at 0.5% of CFF ratio while the flexural strength increased by 125 and 327% respectively with CFF length of 5 cm. Doi: 10.28991/cej-2021-03091753 Full Text: PDF

This study evaluates the effect of substituting cement by volcanic tuff on the workability, mechanical properties, and durability of concrete. Five mixtures were prepared with volcanic tuff ratios to cement of 0%, 5%, 10%, 15% and 20%. First, X-Ray Fluorescence (XRF) test for volcanic tuff was performed. Then, slump test was conducted for fresh concrete specimens. Moreover, tests for flexural strength, splitting tensile strength, elevated heat resistance, ultrasonic pulse velocity, and Scanning Electron Microscope (SEM) were performed at 28-days age of concrete specimens. Compressive strength, and absorption tests were conducted at 28, and 56-days ages of specimens. The study showed that slump, compressive strength, flexural strength, and splitting tensile strength were decreased with the increasing of volcanic tuff to cement replacement ratio at 28-days age. Additionally, the highest compressive strength and lowest water absorption for concrete were obtained at 56-days age of specimens and 10% volcanic tuff to cement replacement ratio.

This research aims to produce a Compressed Earth Block (CEB) product using locally available soil collected from northern Jordan. The CEB mixture was further stabilized using Portland cement, lime, and sodium silicate. The research significance is based upon the urgent need of most developing countries (e.g. Jordan, Egypt…etc) to build more durable and low-cost houses by using locally available materials. As a result, CEB was identified as a cheap and environmentally friendly construction material. CEB specimens were thoroughly characterized by studying the mechanical properties and durability characteristics. Blocks of 30 x 15 x 8 cm with two holes of 7.5 cm in diameter have a potential for higher enduring, higher compressive strength, better thermal insulation, and lower production cost. Blocks were manufactured with an addition of 8 % for either Portland cement or lime, as well as 2 % of sodium silicate to the soil. The results showed that the addition of 8 % of cement to the CEB achieves satisfactory results in both mechanical and durability properties. Also, the addition of sodium silicate was found to enhance the early-age compressive strength however it affected negatively the durable properties of blocks by increasing the erosion rate and deterioration when exposed to water.