No abstract

Accurate prediction of the soil shear strength parameters is essential in the reliable geotechnical design of civil engineering structures. This recent paper investigates the effect of the dry testing condition on the shear strength parameters of the sandy soil using the direct shear apparatus and compared with the saturated condition tests in previous researches on the same soil. The dry soil, usually above the water table, is the principal condition of the Al-Najaf city soil in Iraq. Samples are selected from the site of the University of Kufa, which represents the sandy soil of the city. For reliability purposes, the soil is exposed to different pre-soaking durations (one, two, and four weeks) then air-dried for shear tests. The main results revealed that the angle of internal friction (Φ) tested as a dry sample decreases about -6% up to two-weeks soaking then recovered upon four-week soaking about +6%. Compared to the saturated testing, there are increases in F between 6%-17% from saturated tests. Finally, it is recommended to aware in the selection of testing conditions for calculations of the angle of internal friction.

In this research, the enhancement of compressive, tensile and flexural strength of concrete mixtures was explored using both waste white marble instead of aggregate and steel fibers. White marble was mixed with an ordinary Portland cement replacing the mixture of both coarse and fine aggregate by 10%, 50% and 100% of weight. Besides adding the steel fibres to mixture with a total volume of concrete up to 2%. At the age of 28 days of curing, a significant increase of 24.3%, 34.5% and 38.8% was noticed in compressive, tensile and flexural strengths respectively for the replaced aggregate mixtures. Further improvement was gained by adding the steel fiber.

The aim of study is to produce durable structural concrete by using waste ceramics with specified type (white clay ceramics) as coarse aggregates in concrete. Mechanical properties were studied, the study also show good resistance to fire resistance for concrete contains ceramics as coarse aggregates compared with normal aggregates concrete, good mechanical properties such as compressive, tensile, and flexural strength. Results of study gave 17.5% increment in compressive strength by using 100% replacement of waste ceramic, flexural strength increased with 27.8% increment. Study also show less reduction in strength due to fire resistance by using waste ceramics compared to ordinary concrete, and also more durable concrete for salty water effects by using ceramic.

No abstract