Waterproofing when concrete casting
Concrete casting involves creating a new concrete element as a continuation of an already existing one. Most often it’s impossible to create a monolithic block with a single casting: consider, for example, very large structures or the connection between vertical and horizontal walls. With concrete casting you can obtain monolithic structures with their own characteristics, built in stages at subsequent times. So, you proceed with small blocks and join each casting to the previous one, creating a monolith piece by piece.
Structural connection is achieved by using reinforcing irons, taking special care with drilling the existing block and the length of anchorage. While ensuring attachment to the sequence of blocks, reinforcing irons are potential lines for water seepage. We well know that accumulation of moisture in walls may have very severe consequences: structural fragility and very unhealthy stains and moulds.
An effective solution is to insert bentonite kerbs which waterproof any voids that may have formed at the base of walls or in contact with reinforcing irons. The intrinsic property of sodium bentonite is exploited, which is the ability to swell on contact with water, filling the available space and forming an impermeable compound.
Furthermore, this material provides high resistance to hydraulic load, is easily applied and adheres perfectly to the support.
The range of building products from TeMa Building Solutions also includes T-Bentostop, the waterstop made of hydro-expanding bentonite for waterproofing and sealing concrete casting.
- Published in BUILDING, Concrete paving, Foundation and underground structures - Systems for Waterproofing
Tunnels: the problem of groundwater inflows and water seepage
We are heading towards summer and finally, after two years of the pandemic, people will be making a mass exodus to tourist resorts again. Those who choose the mountains (or the sea, for example, the Ligurian Riviera) will find themselves passing through more than one tunnel.
Italy is one of the countries in Europe with the largest number of road tunnels. As for the TERN (TRANS-EUROPEAN ROAD NETWORK), there are currently about 610 road tunnels in operation covering a total length of about 710 km. The total number of tunnels in operation on ANAS (National Autonomous Roads Corporation) roads is 1,235 km, covering a total length of approximately 755 km.
Especially in older tunnels, you may notice large damp patches running high up the inside walls, or dangerous water stagnation on the ground. So, let’s see what exactly happens and how to prevent the problem.
When building tunnels today, tried and tested systems and materials exist. However, the problem that still needs to be addressed is the hydro-geological aspect, which highlights two main problems: groundwater inflows and water seepage.
By groundwater inflows, we mean the sudden flow of water from walls, coming from an aquifer that finds a new outlet. So, after detecting it, it becomes a priority to plan adequate drainage methods.
Water seepage, instead, refers to the passage of water due to its inherent capillary action or to the force of gravity.
The consequences of groundwater inflows and water seepage can be seen if problems are not tackled, or rather prevented, correctly.
Water is a major threat to structures such as tunnels, since it reduces the life of concrete cladding, causing structural deterioration, endangering systems and posing a hazard to road safety.
What can be done about water?
The ideal solution is to design with suitable drainage systems, with studded membranes and drainage geocomposites.
Maxistud and HDD by TeMa Geo Solutions are HDPE studded membranes with high compressive strength: the former is a 20 mm thermoformed membrane, whereas the latter is a 10 mm membrane bonded to a non-woven geotextile, available in different weights and increasing compressive strengths.
Drainage geocomposites such as Q-Drain ZW5 60 20P TG, 5mm thick with a monofilament core, and a nonwoven fabric can also be used.
The choice of product and the thickness depends on conditions regarding groundwater inflow and the relative risk of water seepage.
The roof: problems to be tackled and solutions to be adopted
“A hole in the roof is enough to ruin a home.”
So the (Italian) saying goes. Of course, there may not be any holes in the roof in the strict sense of the word, but, unfortunately, in a broad sense there might be. Roofs are subject to problems such as water seepage, damp and, in the case of trafficable flat roofs or car park roofs, heavy loads.
The roof is the part of a building directly exposed to weather conditions, such as rain, snow and hail, but also to heavy loads. It’s the least visible part of the house and the most difficult to inspect. When building a roof, it’s therefore essential to consider factors that might affect its integrity and safety, as well as harm the health of occupants.
Water seepage leads to damp and peeling walls. Dampness means mould and unhealthy attic environments.
So, let’s take a look at the main problems and see what solutions can be found.
Ponding on a roof will wet and ruin the materials used. It’s therefore necessary to install a drainage system for rainwater or, in the case of trafficable flat roofs, for accidental leaks of oil or fuel from vehicles. This applies to green roofs, trafficable flat roofs and ballasted flat roofs.
Solutions need to be found that don’t increase the “load” on the roof.
TeMa Building Solutions recommends installing its drainage geocomposite , T-Mix Drain Plus and TMD 1011, ideal for trafficable flat roofs and flat green roofs; its T-Kone G Drain studded membrane, suitable for ballasted flat roofs and flat green roofs; or T-Net Drain geonet for trafficable flat roofs.
It’s also necessary to focus on vapour control. Due to temperature differences between the air and the roof material, there’s a risk of condensation forming. To prevent this, highly waterproof vapour diffusion membranes need to be laid.
The membranes in the T-Vapo range act as a barrier, retarder and vapour diffuser for pitched roofs.
Mechanical protection of waterproofing
The first step is to ensure that the waterproofing layer is intact and remains that way. Any cracks, cuts or inaccurate application in corners can cause irreparable damage to the underlying surface, requiring major intervention and considerable costs. By the time damp patches appear, the damage is often already severe.
Moreover, in the case of roofs used as parking areas or flat green roofs, the heavy weight that the materials need to withstand must be considered.
TeMa Building Solutions proposes its T-Kone G Drain studded membrane and the Tematex range of geotextiles for flat green roofs.
- Published in BUILDING, Drainage geocomposites, Studded membranes and accessories