Today, foundation and grout failures are more commonplace than some might expect in industrial manufacturing. As infrastructure ages, some pose that these failures are inevitable. While the threat of erosion and misalignment over time is always an ongoing concern, certain practices could shorten the lifespan of equipment. One of these practices is poor base installation and grouting.In industrial manufacturing, precision maintenance starts at the foundation – literally. This blog post will discuss poor grouting practices and how laitance may hinder precision maintenance efforts. 

Failure to Remove Laitance

Alt Text: Anchor bolts compress hard shims when they’re torqued.

A standard grout installation error is failing to remove the laitance from the foundation before installing and leveling the sole plate. Concrete is a mixture of sand, cement, and aggregate, with the latter providing the material’s strength. When concrete is poured, the aggregate tends to sink, leaving a surface layer primarily consisting of mortar with little inherent strength. Laitance is the term used to describe that layer. 

After the base is poured, the surface is “roughed up” to provide a strong bonding surface for the grout. It is essential that the laitance is completely removed and the aggregate is exposed before the grout is poured. Failure to do this will inevitably lead to premature erosion and system downtime – with the base/grout system as the root cause. 

Today, a common practice is leveling the base before grouting using hard shims placed under or close to the sole plate anchor bolts. This practice inevitably reduces the life of the base/grout system. 

The Correct Approach to Grouting 

For grout to function reliably, it needs to be placed in compression. When hard shims are used, upon torquing the anchor bolts, the shims, not the grout, are placed in compression. This poor grouting technique leads to premature grout failure.

A more effective grouting technique is to use independent leveling screws to level the sole plate. These screws are protected from the grout with duct tape, foam sleeves, or a release agent, depending on the organization. 

The grout is poured once everything is securely in place. After the grout has cured, the leveling bolts are removed, and their sole plate holes are fully plugged. From there, it’s a matter of torquing down the anchor bolts, thus placing the grout into compression. As illustrated in Figure 2, sleeves should be used on the anchor bolts to ensure they are tightened over the correct effective length.

Alt text: Anchor bold sleeves allowing an anchor bolt to be tightened over proper effective length

Precision Maintenance Matters 

Even when the same procedures are followed, different technicians may approach the same task differently. They are all unique humans with their own ideas and perspectives, and each might interpret a work order differently. This is known as variability, and can become a roadblock to a consistent quality outcome. 

Clear, precise steps for maintenance tasks, such as grouting in a way that keeps the grout in compression, not the shims, can help reduce variability and lead to more consistent precision maintenance. When the entire team is on the same page about how a task should be executed, no matter their tenure with the company or personal preference, variability will decrease, reducing the chances of failure. 

Improve your organization for reliability 

This is where training comes in. When organizations are improved for precision maintenance, especially concerning assembly and installation, there can be a more universal understanding of what needs to be done in the future to reduce poor grouting practices, and all forms of variability. 

To get your operation’s team all on the same page toward precision maintenance, a training class from Reliability Solutions can be an essential tool in optimizing an organization for reliability. Contact us today to find the course that’s right for your team.