Construction World December 2016

GREEN AND FUNCTIONAL HARD LANDSCAPING FOR SILVERSTAR CASINO

The walls were constructed after an amphitheatre, The Dome, designed and built by Otto Wijnberger of In2Structures, had been added to the site. Backing onto Roodekrans Ridge, the largest wall is 128 m from end-to-end and tops 6,5 m at its highest point. Running adjacent to the amphitheatre, it was built by Powergate Construction at an angle of 70˚. Backfill, which varies in depth between 3-3,5 m, was reinforced with Kaytech PC 50/50 geofabric at every third block layer. Wick drains were installed on the cut face at 45˚ every two metres and these channel water into a sub-soil drain. Further drainage is provided by a rain channel which was installed in the backfill behind the top layer of blocks. Indigenous trees, grasses and shrubs combine with the foreground paving to complement and soften the retaining wall particularly well, while the red soils used for the backfill have stained the grey blocks, resulting in a colour mix that blends in well with the surrounding environment. Three concrete retaining block walls have been built at the Silverstar Casino entertainment complex in Krugersdorp using CMA member, Terraforce’s L11 blocks. The blocks were supplied by Terraforce licensee and CMA member, ReMaCon Products cc, and the walls were designed by ReMaCon CEO, Silvio Ferarris. The findings of the geotechnical investigation conducted by MSJ were used to determine representative in situ geotechnical parameters for the geogrid reinforced soil foundation mattress design. The investigation consisted of 11 TLB dug test pits and five rotary cored boreholes. Pocket penetrometer tests, vane shear tests, and point load index tests were carried out in addition to laboratory testing comprising grading analysis, Atterberg limit determination, Mod. AASHTO compaction and CBR tests. The investigation highlighted rock at level between 11 m and 12,7 m below natural ground level and a completely weathered clayey zone between 14,2 m and 16 m below NGL. Moreover, rock level was found between 18,78 m and 20,5 m below NGL. Rock has been found above these levels but there are also completely weathered zones and a relatively thick clayey zone between 12,5 m and 20,5 m. The combination of high pressure loading and the presence of clay with an undrain shear strength in the range of 50 to 100 kPa for the first 6 to 10 m resulted in failure in bearing capacity resulting in the need for foundation improvement techniques. The remote location of the site has strained and limited the possible solutions as access and the availability of material and equipment would MSJ Geotechnical Consulting Services were appointed to carry out the foundation design for the New Maize Silos at Mashamba, Democratic Republic of Congo in order to cater for the 322 kPA loading from the strip footing and 180 kPa from the 28 m high maize. MAIZE SILOS AT MASHAMBA, Democratic Republic of Congo

Project information • Company entering: Remacon • Start date: May 2015

• End date: October 2014 • Main contractor: WBHO

• Consulting engineer: Remacon Products • Subcontractor: Powergate Construction

The two other walls, one 95 m long and three metres high and the other 91 m long and two metres high, were built to secure embankments on the fringes of two parking areas. Both were built by Powergate Construction using the same L11 block and to the same design specifications as the larger wall. The Terraforce L11 block has a round face finish which is easily planted. Moreover, the L 11 system is also cost-effective and easily constructed in uniform concave curves. Terraforce blocks are exclusively manufactured in Gauteng by Remacon Products.

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Project information • Company entering: Maccaferri Africa • Start date: January 2016 • End date: March 2017 • Project team: MSJ Geotechnical Consulting Services • Consulting engineers: MSJ Geotechnical Consulting Services

have had to be brought in, delaying the execution of the project. MSJ and Maccaferri Africa had successfully used basal reinforcement techniques in the past for similar situation and it has been proven to be cost effective with high margin of safety and short installation time. The proposed solution consisted of excavating the in situ material to a depth of 2 m below the soil mattress level. Two layers of Paralink ® 600 are then placed bi-directionally (second layer placed with straps at right angles to the first) onto the in situ material. A separation layer comprising 100 mm graded gravelly sand specially selected from the laterite source, lightly rolled, is placed between the Paralink ® 600 in order to enhance the friction between the geogrid and the soil in order to transfer the stresses from the soil.

2 16 BEST PR O JECTS

DECEMBER • 2016