Drewholick.net

I took a tour of the Hanson Pre-cast Concrete Plant in Houston, Texas. This particular plant is located just off US 290 on the northwest side of Houston. The tour was facilitated by Hanson and the Engineer Assistants Group of the Bryan District, TxDOT.

The tour started with the dry-formed box culverts. This image shows the box form (an outside and inside form are used). The yellow machinery is used to batch concrete to the form. The form is also vibrated while the concrete is placed (very loud process).

This next image is of the steel reinforcement for the box culvert. This process uses wire mesh as reinforcement for the concrete. The reinforcement is assembled manually around a bottom form. The outside and inside forms are placed around the steel.

This is a recently formed culvert. It was removed from the form approximately 20 minutes previous. The plywood is bracing on the inside of the form to keep it from collapsing until the concrete reaches final set. In addition, workers smooth the edges and patch and gaps in the surface finish.

The plant is relatively large. It was more efficient to drive from each building to see everything than to walk.

Here, the tour group is getting a description of the process dry-forming process. We moved outside as the workers had started vibrating the forms.

This is an image of some of the products produced at the plant. This is a pre-cast,integral headwall and wingwall section for RCP. Beind it you can also see large box culvert. On the left you can see a profile of the headwall and wingwall section and see that it also includes the toewall and apron.

The tour moved on to the wet-forming process. This process is used for custom work or standard items that are not suited for the production line style of the dry-forming process. We also picked up a new tour guide, the manager of the wet-forming section at the plant.

This is a small box that has recently been released from the form. The wet-forming process takes a bit longer than the dry-forming process. This box was poured the previous evening. The system is similar in that there is an outside and inside form and the concrete is vibrating in the form.

This is an inlet box being formed. You can see the reinforcing steel cage and the inside concrete form. In addition, you can see the lifting lugs attached to the steel reinforcement.

This image is the opposite side of the previous box. You can see lifting lugs and a plug that will leave a circular hole in the finished box. The plug is made from styrofoam.

This is an image of the styrofoam plugs being cut. The plug is covered with tape where it meets the concrete to ease removal and allow the plug to be used multiple times before it has to be replaced.  The styrofoam is cutting using a hot wire.

This is a one of several concrete batch locations around the plant.  Concrete can be batched directly 2 or 3 yard buckets and hauled around the building or directly a batch truck or even the forms.

The plastic is wrapped around some recently placed concrete culvert.  The forms are wrapped and plastic and then cured using steam generated on-site.  The steam cure take approximately 6 hours at a minimum but can go longer.  This process reduces the time required for the concrete to be in the form and increased production.

Trackback URI | Comments RSS