Construction World February 2020

READYMIX

SPECIALISED ADMIXTURES USED ON M2 BRIDGE REHABILITATION

CHRYSO Southern Africa is proud to have been the supplier of specialised admixtures for the recently completed M2 bridge rehabilitation project in Johannesburg, according to Hannes Engelbrecht, CHRYSO General Manager: Inland Sales.

the ideal solutions, to achieve the optimum, ͤW IRU SXUSRVH PL[ IRU WKLV DSSOLFDWLRQ -DFREV HODERUDWHV ̸'XUD3R]] ͥ\ DVK ZDV LQFRUSRUDWHG LQWR WKH PL[ WR UHGXFH WKH DONDOL content, as a prerequisite to eliminate the possibility of future ASR deterioration. 7KH DGGLWLRQ RI &+5<62̵V DGPL[WXUHV from the Optima and the new Quad ranges, ensured that durability parameters and SODFLQJ UHTXLUHPHQWV ZHUH PHW ̹ (QJHOEUHFKW H[SODLQV WKDW &+5<62̵V philosophy, is to put their customers' priorities at the heart of their business. Harnessing relationships by supplying TXDOLW\ FKHPLFDO DGPL[WXUHV FRXSOHG ZLWK H[SHUW WHFKQLFDO VXSSRUW LV WKH mainstay of CHRYSO’s success. Engelbrecht and Jacobs agree that the success of this project was a joint initiative, building on a long-standing association between CHRYSO and Lafarge 5HDG\PL[ 7KH UHKDELOLWDWLRQ RI WKH 6HOE\ and Kaserne bridges used more than 1 000 m 3 concrete, incorporating optimised DGPL[WXUH GRVDJHV $V WKH 0 ZDV FRPSOHWHO\ FORVHG GRZQ GXULQJ WKH FRQVWUXFWLRQ SHULRG WKH H[HFXWLRQ of the rehabilitation commanded great urgency, leaving no room for error or delay. $OO WKH UHDG\PL[ ZDV VXSSOLHG IURP /DIDUJH̵V Wynberg plant, which ensured consistency of the concrete, with the Cleveland plant as back-up facility. CHRYSO’s supply team HQVXUHG WKDW DGHTXDWH DGPL[WXUH VWRFNV were maintained throughout the project. 7KH 0 ZDV UH RSHQHG RQ VFKHGXOH DW WKH HQG RI 2FWREHU ƒ

CHRYSO Southern Africa supplied specialised admixtures to Lafarge for the M2 bridge rehabilitation project.

C HRYSO’s comprehensive range of DGPL[WXUHV SOD\V D YLWDO UROH LQ PDQ\ SURMHFWV RSWLPLVLQJ FRQFUHWH PL[HV WR HQVXUH WKDW VWULQJHQW FRQFUHWH VSHFLͤFDWLRQV DUH PHW 7KH 0 EULGJH UHKDELOLWDWLRQ ZDV QR H[FHSWLRQ Following concerns over the safety and structural integrity of the Selby and the Kaserne bridges, the Johannesburg Roads $JHQF\ FORVHG WKH 0 EHWZHHQ WKH &URZQ ,QWHUFKDQJH DQG 0DULW]EXUJ 6WUHHW DW WKH HQG RI )HEUXDU\ Investigations found that sections of the concrete bridge elements were severely compromised, identifying alkali silica reaction (ASR) as the cause of the deteriorating concrete. These deteriorated elements were subsequently demolished in preparation for the casting of new concrete. It follows that durability criteria, according to the South African Durability ,QGH[ ZHUH SDUDPRXQW LQ GHWHUPLQLQJ

WKH FRQFUHWH VSHFLͤFDWLRQV IRU WKH QHZ HOHPHQWV :DWHU VRUSWLYLW\ DQG R[\JHQ permeability were the durability parameters HYDOXDWHG IRU WKH FRQFUHWH PL[ 7KH QHZ elements were heavily reinforced and access OLPLWHG FDOOLQJ IRU D SDUWLFXODUO\ ͥRZDEOH PL[ in order to aid the concrete placing and to minimise/eliminate the necessity of using SRNHU YLEUDWRUV :KHQ /DIDUJH 5HDG\PL[ ZDV FRQWUDFWHG WR VXSSO\ WKH VSHFLͤHG 03D UHDG\PL[ FRQFUHWH 'DUUHQ -DFREV /DIDUJH̵V 7HFKQLFDO *OREDO %UDQGV 0DQDJHU LGHQWLͤHG WKDW D UREXVW PL[ ZKLFK ZRXOG FRPSDFW easily and meet all durability requirements was required. Lafarge’s Agilia concrete, ZKLFK LV HQJLQHHUHG WR ͥRZ DQG VHOI FRPSDFW XQGHU LWV RZQ ZHLJKW HIIHFWLYHO\ ͤOOLQJ WKH entire formwork without requiring vibration, was selected as the best option for this project. It soon became apparent that CHRYSO’s UDQJH RI FKHPLFDO DGPL[WXUHV SUHVHQWHG

CHRYSO admixtures played a vital role in the M2 bridge rehabilitation project.

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CONSTRUCTION WORLD FEBRUARY 2020