Construction World May 2018

DAMS & RESERVOIRS

Major role in water CONSERVATION With water preservation of critical importance in many parts of South Africa, a.b.e. Construction Chemicals has a wide range of products available to prevent failures in concrete reservoirs and other water-retaining structures. a.b.e. is part of the CHRYSO Southern Africa Group.

a.b.e., as well as its holding company, CHRYSO SA, were used for the Lilongwe Water Board’s new Water Treatment Plant. For the repair of the Lilongwe Water Treatment Plant, a.b.e. supplied duraflex flexible cementitious waterproofing slurry for the internal application to the plant’s silt tanks and water clarifiers. a.b.e.’s durasil SH silane siloxane water repellent treatment was used as external coating of the water reservoir to reduce the ingress of chloride irons and carbonation attack. Other a.b.e. products used for the Lilongwe Water Treatment Plant project included durajoint PVC Waterstop for the joints; durarep QS fast-setting concrete repair and anchoring material; as well as a.b.e.’s precision non-shrink cementitious grouting, duragrout, to provide full bearing support for the plant and machin- ery installations. CHRYSOCure acrylic emulsion was used to aid curing and reduce the incidence of shrinkage cracks while promoting full strength development; and CHRYSOPlast Omega 122 water reducing super-plasticiser to obtain high performance concrete with a low water-cement ratio. Both a.b.e. Construction Chemicals’ and CHRYSO products were used to build the new Mndwaka Dam on the Eastern Cape’s Wild Coast. The dam – which provides water for 63 remote rural villages – was awarded a Commendation in the Concrete Society of South- ern Africa’s 2017 Fulton Awards. a.b.e. supplied the following range of products for the building of the multiple arch-buttress dam: • brixeal bitumen emulsion waterproofing product was used to seal concrete surfaces while also acting as a curing agent; • duragrout, a cement-based grouting compound with graded siliceous aggregates and chemical reagents was applied to prevent shrinkage during curing; • epidermix 344 structural wet-to-dry adhesive was used to bond fresh concrete to existing concrete; • durarep FR fibre-reinforced cement-based mortar was used for structural repairs; and • epidermix 318 general purpose epoxy for the repair of minor defects. AfriSam, which supplied the cement and formulated the concrete mix for the construction of the dam, incorporated CHRYSOPlast Omega 136 water-reducing plasticiser in the mix. Elrene Smuts, Communications Manager for the CHRYSO Group, says the use of additives to make a concrete mix waterproof and watertight has proved successful in both below ground and water containment environments. “There are two principal areas of tech- nology and products in this field: crystalline-based products such as CHRYSO SA’s CWA10 crystalline waterproofing admixtures, or the pore blocking system, Fuge B, a hydrophobic additive applied during the concrete mix stage to block pores in the concrete to prevent the passage of water,” Smuts explains. She says waterproofing options available in South Africa are complex and rapidly changing so, to avoid confusion and disas- trous results, it is wise to consult experts before specifying for any project. “Both a.b.e. Construction Chemicals – which has been involved in waterproofing for over 80 years – and CHRYSO SA have the technological experience and expertise to help in this regard,” Smuts adds.  Products from a.b.e. Construction Chemicals and CHRYSO SA have been used for the construction and maintenance of water retaining structures ranging from massive water projects such as the Katse Dam to smaller municipal sewerage systems throughout Southern Africa.

A t Savana City in Sebokeng, a.b.e.’s durajoint flexband system was for used to seal a new 10 mega litre concrete reservoir. The durajoint flexband system provides the ideal solution for sealing of joints in potable water reservoirs. The system includes: • durajoint flexband thermoplastic elastomer membrane; • durajoint special epoxy adhesive for bonding the durajoint flexband; and • durajoint HDPE strip, durajoint flexband solvent wipe, bond breaking tape and the appropriate sealant for various substrates. The system can restore failed joints, repair and seal structural cracks, and for the sealing of joints subject to chemical attack because it is resistant to a wide range of chemicals. In addition to waterproofing concrete reservoirs, the system can be used on a variety of substrates, including damp substrates and can also be used in contact with potable water. The bandage is supplied in 20 metre rolls and several widths. In another major project, a.b.e. waterproofing products were used in Malawi for the upgrading and rehabilitation of Blantyre Water Board’s three potable water reservoirs; while products supplied by

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CONSTRUCTION WORLD MAY 2018