Technical articles

The design of industrial floors in warehouse, manufacturing, and distribution center's is a critical aspect that often goes unnoticed amidst the construction process. However, neglecting proper floor design can lead to...

An industrial concrete floor’s principal duty is to serve as the work surface for the intended use of the building.  Ideally, this working surface needs to be durable, flat and provide an uninterrupted platform. Unfortunately...

Concrete slabs and pavements are all around us, and if we are building owners we will own a lot of the hard grey stuff yet how much...

Armoured Joints are an important consideration when designing and constructing industrial floor slabs. Not using a steel armoured edge to protect the aris of the joints edge will result in...

Thinking Smarter and Greener with GFRP Reinforcement and dowels With tensile strength 2x that of steel and non corrosive, Casta Smart-Bar glass fiber-reinforced polymer (GFRP) rebar is designed to replace...

How to mitigate the risk of corrosion in concrete though using Glass Fibre Reinforced Polymers (GFRP) Corrosion of steel dowels in concrete slabs have been an issue for as long...

What is load transfer? A concrete floor is often constructed in many panels and the point where one panel meets another is called a joint. Anything on top of the...

WHY CARE ABOUT JOINTS? We often get asked why we put so much emphasis on joint layout and joint type in our slab designs. There’s a specific reason for...

We often get asked how can fibre reinforcing provide a stronger slab than traditional mesh reinforcing? The tensile strength of reinforcing mesh only comes into effect when it is bridging a macro (or visible) crack in the concrete matrix. On the other hand, short separate fibres provide a discontinuous, three-dimensional reinforcement that picks up and transfers load stress at a micro-crack level. This means that fibres provide strength and help to control micro-cracks, even before they form. This encourages higher ductility or toughness. Additionally, using fibre provides three-dimensional reinforcement from the top of the slab right through to the bottom, as opposed to a two-dimensional single layer of reinforcement provided by mesh. Talk to our engineers today to see how you can use fibres to increase the strength and durability of your concrete slab or structure.

WHY CARE ABOUT JOINTS? We often get asked why we put so much emphasis on joint layout and joint type in our slab designs. There’s a specific reason for this: the joint is one of the weakest elements in a slab or pavement design. Unless it’s properly protected, the joint will become not only a major long term maintenance issue but also a point in the slab that creates a rough and noisy crossing for your materials handling equipment. THE EFFECTS OF POORLY DESIGNED JOINTS Adequate load transfer at the joints in the slab is critical to the long term durability of the overall floor. Poor load transfer means that adjacent panels will deflect independently under an applied load, producing an uneven floor. This in turn will cause further damage to both the floor and material handling equipment. HOW TO ADDRESS THIS ISSUE In high movement environments, we recommend using ...

Swap mesh for fibre and halve your carbon footprint We’re passionate about optimising concrete slab and pavement designs – not just because they can be made more durable and cost-effective with fibre, but also because there are substantial environmental benefits to be had through optimised designs. As an example, using fibre in slab on grade projects to replace steel mesh results in better quality designs that minimise waste and have a substantially reduced carbon footprint. Studies have shown that using fibre reinforcement in concrete as an alternative to conventional steel rebar can reduce the carbon footprint of an industrial floor by as much as 56%. This is due to the reduction in manufacturing and transport emissions when compared to traditional mesh. Mesh is heavy to transport, difficult to handle and time-consuming to set up. In contrast, fibre reinforcement is only a fraction of the mass of conventional reinforcement, meaning significant ...

Traditional concrete is made from sand and aggregates mixed with Portland cement. The cement, sometimes incorrectly referred to as ‘concrete’, is in fact a separate element of the concrete mix itself. Cement (portland) is a manufactured glue binding agent that begins to set hard with the introduction, and then evaporation of water. In the case of geopolymer cement, an alkali is used to kick off the chemical curing process. The hardening process continues near indefinitely over the life of concrete, but around 90% of final hardness is achieved in timeframes of a few days to a few weeks depending on atmospheric and initial mix conditions. The most common cement used worldwide, is known as portland cement, and has essentially been the founding product of modern construction, worldwide, during the modern industrial age of humans. Our society is built from the use of portland cement mixed with stone and sand to ...

As a general rule, we make the pavements with the premise that they are flat. Flatness is the main characteristic that we request a slab. Even when we execute it with slopes due to operational requirements, generally of water evacuation, we need that inclined element to be as homogeneous as possible. Rare will be the pavement where we do not need to resemble a plane. Being it is not possible, from a practical point of view, to get a perfect plane with concrete, every pavement should bring in its specification what degree of deviation on that ideal will be allowed, and it will depend on whether we are inside those tolerances, the quality of the work we have done.   We are going to focus on this article on how we should choose those tolerances depending on the final use to which the slab will be subjected. For this we ...

Curling is a phenomenon that occurs in concrete slabs, lifting the edges of them and causes problems such as: Level change between slabs, which effect to the passage of vehicles, especially noticeable with small and hard wheels Breaks of the slabs when applying loads on the edges, which are literally flown on the base of the pavement Worsening of the flatness. The regulations in this point demand to measure in the first hours or days after the execution, nevertheless, a later pronounced curling can make the activity for which that floor was executed be limited or impossible This phenomenon has a main cause that we know, which is the drying, temperature and differential retraction between the top of the slab with respect to the bottom. It seems evident that concrete drying occurs more quickly on the surface, which causes greater retraction (and, therefore, more volume loss) in the upper layers ...

What is load transfer? A concrete floor is often constructed in many panels and the point where one panel meets another is called a joint. Anything on top of the concrete floor applies pressure (or a load) to the slab. When materials handling equipment (MHE) moves across the floor and approaches a concrete slab joint, the panels need to work together to adequately carry the load applied by the MHE. This interaction between each panel (called the approach and leave slabs) is achieved by load transfer. Load transfer is considered at joints and cracks in concrete floor slabs and can be defined as the ability for a slab to transfer shear to an adjacent slab. The load transfer ability of a joint or crack has a direct influence on vertical displacement between two slabs. Poor load transfer means that adjacent panels will deflect independently under an applied load, producing an ...

Early work by the US Army Corps of Engineers (Ludirdja and Young, 1993) investigated the effects of exposure to various poly fibres.  Polyester, polyacrylics, and polyamiucs (nylon) can potentially undergo alkaline hydrolysis in the presence of the highly alkaline pore water (PH>12.5).  In practice, this effect depends on the degree of saturation of the concrete, and the rate hydrolysis will occur. The rate of fibre degradation will be limited by diffusion through fine capillary pores (0.1 to 0.0025 mm) and micropores (<0.0025 mm) and surface diffusion through films of adsorbed water on the walls of the larger pores. Capillary pores down to 0.1 mm in diameter will be largely empty of water at 70 percent Rh and hence the movement of water within the concrete is restricted. This will reduce the rate at which hydroxide ions can reach the surface of the fibres to initiate hydrolysis. Unless hydrolysis advances to ...

Synthetic fibres are fibres manufactured from organic polymers from many formulations: acrylic, aramid, carbon, polyester, polyethylene, and the most common nylon and polypropylene. Synthetic fibres are engineered to withstand the long-term alkaline environment of concrete. Synthetic fibres fall in 2 categories, micro synthetic fibres or macro synthetic fibres. (Fibers, 2018).  Macro fibres are so named due to their larger size.   Macro synthetic fibres, due to their length and unique design, produce an excellent mechanical bond.  The macro plastic fibres can be virgin and recycled polypropylene (PP), high-density polyethylene (HDPE), or polyethylene terephthalate (PET) fibres. PP fibres have been widely used in the concrete industry, due to the ease of production and high alkaline resistance (Yin. et. al., 2015).   Representative properties from iNFORCE Radforce synthetic fibres include: Polyolefin polymer material Fibre Length 48 mm. Width 1.29 mm. Tensile Strength Min.  550 MPa Fibres can be added during conventional mixing, ...

Cellulose fibres provide excellent crack control due to the fibre properties to include: high fibre surface area, close fibre spacing, and excellent bonding within the hydrated cementitious matrix (Soroushian 1996).   Cellulose fibres are used to improve impact resistance and increase surface durability to plastic shrinkage cracking (Buch 1999).   There are different materials are used for concrete fibre manufacturing. These different materials used lead to concrete performance features and benefits specific to job-type. The efficacy of a fibre in the concrete is generally based on two parameters: shape and material type. The influence of shape on fibre-concrete bond is discussed in a previous article (See Shapes of Fibres).   When the concrete fibre is mixed into fluid concrete, some of the paste volume of the concrete mix saturates the surface of the concrete fibre. As the concrete cures and hardens, the fibre is mechanically anchored into the hardened paste. ...

PHOTO: Concrete Beam Tested in a Third-Point Flexural Apparatus, Courtesy SELlabmanager In our Concrete Strength series, we discussed the flexural strength of beams; the failure lines are discussed in the book Concrete Strength 1–2–3. A picture of a laboratory demonstration of a nonreinforced beam in failure is shown above illustrating the propagation of cracks from the extreme concrete fibre in the tension zone. The cracks are moving through the tension zone towards the neutral axis of the concrete beam. Cracks open in shear in the left and right thirds (diagonal lines) and in tension in the middle third (vertical lines). Once cracks initiate they want to open, increase deflection, normal to the crack. This is a tension stress state. We are familiar with reinforced steel design for beams which is designed to carry the tension stress in the bottom of the beam to resist cracking. What are possible alternatives for ...

PHOTO: Concrete Slab Curling, Courtesy of DCI Coatings blog   Curling in concrete is a significant problem, especially in pavements. NRMCA defines curling as the distortion of a slab into a curved shape or upward or downward bending of the edges, [NRMCA, 2004]. If the curling is significant enough, the slab can crack and potentially have a structural failure. Most often times curling occurs from significant swings in temperature or moisture in the slab.   So, how do fibers resist curling?   Curling due to temperature is induced by a temperature differential in a slab. Higher temperatures cause concrete to expand causing tension. Drying of concrete causes concrete to shrink causing compression. Fibres serve as mini reinforcement which can resist tension strain (movement caused by the induced tension). Fibres help hold the mix together, creating a stronger more durable concrete when used appropriately. In general, for curling to occur with fibres ...

Another parameter that impacts the abrasion resistance of concrete is the surface mortar and secondary concrete layer of the concrete surface. Both are directly affected by wear and it is important to ensure these materials are given ample opportunity to hydrate and not be hampered by plastic shrinkage and the associated cracks that are developed. The above image shows an Electron Microscope Image of the Topside of the Trough from a Concrete Sample Tested by ASTM C 779, Procedure C. Upper left corner is the top of the concrete slab and the bottom right corner is the top of the trough.   Plastic Shrinkage Plastic shrinkage includes those cracks that appear at the surface and secondary layers of concrete between the time that the concrete is placed and its initial set (penetration strength of 500PSI). The cracking takes place while the concrete is still in its plastic state. ACI recognizes ...