Construction World December 2022

PROJECT INFORMATION

• Company entering: CoreSlab • Client: Venetia Mine • Main Contractor: BMH Africa • Architect: CSKO • Subcontractor: Coreslab

VENETIA MINE RESIDENTIAL DEVELOPMENT

D e Beers’ Venet ia Mine’s mine accommodat ion projects are being fast tracked us ing hol low-core slabs to construct suspended slabs . Coreslab has helped Woodtec Construct ion, principal contractor, and BMH, project manager, del iver more than 100 res ident ial uni ts for De Beers’ Venet ia Mine. Last year, Woodtec Construct ion, BMH and Coreslab completed 33 apartments and 12 houses in Mus ina in record t ime. On the more recent mine accommodat ion projects , Woodtec Construct ion and BHM were again working to a ver y t ight schedule. The use of hol low-core slabs ensured swi f t and ef ficient construct ion of the uni ts . Hol low-core slabs provide a faster method of construct ing a qual i ty suspended slab. Hol low-core slabs are reinforced or pre-stressed concrete slabs , compri s ing cores that extend the ful l length of the elements . They general ly var y in thickness f rom 150 mm to 300 mm and span up to 14 m, depending upon loading, and are between 300 mm and 1 200 mm wide. These precast-concrete elements are placed on a 5 mm to 20 mm-thick level l ing screed on masonr y wal ls wi th a minimum bearing of 100 mm. To accommodate thermal movement on roofs or exposed balconies , bi tumi sed sof t-board or other s imi lar materials are used. Thi s makes al lowance for changes in camber or deflect ion, part icularly where l ight parapet wal ls are bui l t on pre-stressed hol low core slabs . Light mesh reinforcement i s also placed in the fini shing screed or topping in these ci rcumstances . Hol low-core slabs are s igni ficant ly l ighter than a large sol id concrete suspended slab of equal thickness or strength due to the use of fewer raw materials . Thi s reduces the cost of manufacture and transportat ion of the “planks” to s i te where they are l i f ted and placed, level led and grouted to complete the suspended slab. However, one of the biggest advantages of

hol low-core slabs i s that they are manufactured in a control led factor y envi ronment where the non-modular sect ions are also cut to s i ze according to the bui lding dimens ions immediately af ter the concrete has reached the requi red strength. The various elements are then transported to s i te where they are l i f ted di rect ly f rom truck and placed on top of the load-bearing wal ls us ing a mobi le crane or truck-mounted boom crane. Once they have been instal led, bui lding contractors and trades are able to work on the structure almost immediately to s igni ficant ly accelerate the bui lding project . Thi s includes above and below where there i s no propping or staging. The bui lding contractor also does not have to fi rst wai t for the concrete slab to cure to proceed. Coreslab can instal l an element ever y five minutes to complete a floor structure in record t ime. Thi s speed i s also faci l i tated us ing special l i f t ing tackle that has been engineered by the company. The growing populari ty of hol low-core slabs in thi s market i s largely being driven by the severe workload in a ver y compet i t ive and volat i le industr y. These factors are being exacerbated by widespread ski l ls shortages in the construct ion sector. Home bui lders and thei r profess ional teams want peace of mind that the instal lat ion wi l l be done correct ly the fi rst-t ime round, whi le smal ler archi tectural and structural -engineering fi rms are also increas ingly speci fying hol low-core slabs in the early des ign stages of the project to mi t igate ri sk and reduce construct ion costs . High levels of accuracy also minimi se wastage, another notable benefi t of hol low-core slabs that i s complemented by the s igni ficant cost-savings in concrete, propping and labour that i s associated wi th the use of both in-s i tu construct ion methods and rib and-block systems . 

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21 st Best Project Awards 2022