IINNTTRROODDUUCCTTIIOONN Basement walls require protection to prevent water/moisture ingress to avoid steel reinforcement corrosion, damage to stored goods, mould, mildew development and sick building syndrome. Conventional concrete, reinforced concrete masonry walls and shotcrete walls that are in direct contact with the ground cannot stop water/moisture ingress. They are porous and will develop cracks even if they incorporate joints. Water ingress through the walls causes corrosion and eventually may even cause structural failure. The common prevention method for water/moisture ingress of basement walls is the application of waterproof membrane systems. However, there is no 100% guarantee with conventional membrane systems. (For further information refer download – Dincel Wall Waterproofing Warranty). The steel reinforcement in basement walls will corrode when in contact with the following conditions: 1. In air, relative humidity of over 50% provides the necessary amount of water and at
80% or above, the corrosion of bare steel is worse. 2. Water (potable, gray, waste water), salts (e.g. sea water), aggressive soil conditions
(e.g. acid sulphate soils), storage of sewage, acids, oils and chemicals in liquid or gas form.
3. Stray current corrosion by electrified rail systems or corrosion protection systems
(e.g. cathodic protection). Refer for further information download – Dincel Solution for Stray Current Corrosion Protection.
To avoid the above the best possible solution is offered by Dincel Walls which is tested by the CSIRO – Australia as waterproof walls (download – Waterproof walls) without the need of membranes. The benefits of Dincel Wall are summarised in the following page.
DINCEL-WALL ELIMINATES: Loss of valuable land use Waterproofing need for the wall Stray Current Corrosion damage Excavation behind the wall Backfilling the excavation Wall joints Agricultural lines Conventional footings Horizontal wall reinforcement Scaffolding Painting of the internal wall face Cleaning costs Wastage Builder’s Liability for wall
cracking, water damages DINCEL-WALL ALLOWS: Habitable spaces in basements Minimum 100 years wall life Stronger structural walls in
BBAASSEEMMEENNTT EEXXCCAAVVAATTIIOONNSS The basement excavation may take place with the following methodologies: To utilise Dincel-Wall in basement construction the contractor will need to finalise the basement excavation. (i) GROUND EXCAVATION BY SHORING (Refer Figure A) Shoring may take place in the form of discrete concrete or steel piles to stabilise the
basement soil excavation for a temporary period during construction until the permanent structure incorporating Dincel-Wall is erected. The excavation in sand or sandy soils or even medium to soft clay soils may require a continuous shoring system. This may consist of contiguous piles (piles as close as possible to each other) or secant piles (soft and hard piles overlapping each other which are normally used for construction below the permanent water table) or alternatively, as shown on Figure A which is a sheet piling system may be used. The sheet piling normally engage ground anchors until the placement of the permanent structure. Sheet piling similar to secant piles are also used when basement construction is subject to high water table conditions or having granular soil excavation.
The sheet piles in association with are treated as temporary shoring
purposes as they can be either removed or left in place to rust away. The supply of sheet piling is determined by its thickness and how well the joints of the sheet piling will retain the water. The sheet piling suppliers in association with do not need to consider the additional corrosion allowances for sheet thicknesses. Their sheet thicknesses can be determined by the drivability issue rather than corrosion. However, drivability issues can be easily overcome by pre-drilling the ground where required. The joints of the sheet piling can be allowed to leak as long as the leakage is within the de-watering limits. Today’s sheet piling technology is well advanced and soft to medium clays can be shored with the assistance of vibrationless hydraulic rams pushing into the soil, where required ground is pre-drilled to assist the drivability.
Experience shows that permanent sheet piles incorporating shotcrete concrete walls often fail to achieve a waterproof basement structure. This combination cannot be relied on, especially in permanent water conditions due to the following reasons: (1) Total waterproofing at the clutches of the sheet piling cannot be achieved
due to many reasons. (2) Cracking of the shotcrete concrete wall is unavoidable.
(ii) GROUND EXCAVATION BY BATTERING (Refer Figure B) The ground may be excavated vertically, varying slopes and steps, depending on the
