What are Concrete Screws?
Over the past decade, concrete screws have become a popular alternative to traditional masonry anchors such as anchor bolts and expansion shields. They are used in a number of applications, but they are most frequently found in concrete masonry construction, concrete blocks, concrete pavers, concrete piers, and wood-to-concrete connections. So what are concrete screws?
How Are Concrete Screws Used?
Concrete screws can be installed into concrete, masonry units, pavers and piers. The installation process is simple and concrete screws can be attached to concrete with little difficulty or special equipment. One important consideration before installing a concrete screw anchor is the length of the anchor as it relates to the thickness or depth of the member being fastened together.
In most applications where you would use a concrete screw as an alternative to traditional anchoring devices, longer threaded depths can typically be achieved with less difficulty than shorter lengths because there is more room for a wrench to fit onto a socket head cap screw. This means that in most cases a longer penetration depth will result in a stronger connection due to increased torque.
Concrete Screws vs. Expansion Shields
Many factors contribute to how concrete fixings or reinforcing steel is selected for a specific job but one of the most important factors in choosing the right concrete fastener is an assessment of tensile stresses placed on concrete members during service. When evaluating tensile stresses in concrete design it is necessary to consider both dead loads and live loads acting on concrete members such as footings, beams, and slabs.
The majority of dead loads placed on concrete come from the weight of the member itself while live loads can consist of induced and imposed forces such as soil pressures (applied earth-pressure) and applied water pressure (hydrostatic pressure).
Concrete screws provide a certain level of resistance due to their design, and if possible, can be the first choice for professionals and DIYers alike for masonry fixings because of their practicality – they are a single screw that does not need any additional equipment.
Concrete expansion shields, which are also known as shield anchors, can be used to provide additional resistance to these tensile forces in concrete members. When using concrete fixings such as concrete screws and concrete expansion shields they must be installed according to the load conditions of the member and building code requirements.
When assessing whether a concrete screw or concrete expansion shield is appropriate for a given application, we need to consider not just their strength properties but also how easy they will be to install in thick material.
Installation
Expansion shield installation requires the use of an expander plug which needs more space than other types of concrete fasteners such as concrete screw anchors (Ankerbolts). Ankerbolts do not require any additional parts other than what is required for concrete bit installation.
Concrete screws can be installed vertically or horizontally in concrete walls, concrete slabs and concrete beams depending on the specifications of a given project. Concrete expansion shields are typically installed horizontally when attaching concrete slabs to concrete beams and concrete columns.
When installing anchor bolts, it is common for a worker to drill a pilot hole slightly smaller than the diameter of an expander plug using a concrete bit with a centre point tip.
The expander plug must have protruding ribs that allow them to expand once inside the hole being drilled in the concrete. We then put two bolts through the head of the expander plug after expanding it with a wrench or hammer before inserting it into its final position inside the drilled hole with washers and concrete screws.
When concrete expansion shields are installed concrete screw heads must be fully seated into the concrete shield to avoid pull-outs.
The range of concrete screws at Fusion Fixings is growing
