Rutland Products 25 lbs Castable Refractory Cement, 2200F, Taupe, 25 Pound

I had the back slab develop a 4" hole. Shut down the FP and scurried to find out how I could access it and find a replacement. Found both, placed an order and then worked on disassembling to get the slab out. A week or so later, I hadn't received shipping information so I contacted the vendor and found the slab was back ordered and would be shipped on Feb 5th. Not trusting the actual date supplied, I started searching for possible repair solutions and found the Castable Rutland product. I'd used other Rutland products but was a bit concerned due to my lack of cement knowledge and some of the reviews I read. I decided to take a chance as the coldest part of the winter was upon us and I burn 24 x 7. I planned my approach and in a couple days I had the cement (left input in questions about getting the top off), had a board to sit it on and some wax paper that I planned to put between the 4 " hole in the slab and the board I was putting it on. I used another stick to define the edge of the hole to be filled and a couple of bar clamps to hold everything in place. Now I was ready to go. I brought the slab to the cellar and realized that this might just not work. The slab not only had the hole but fractures that were threatening to break the entire slab in half. I started doubting my entire approach. I gingerly set it onto my board and got it stabilized with the bar clamps. Mixing the cement was easy as long as you didn't add too much water. I just mixed it comparing the final product to a too thick pancake batter. With a trowel, I started picking up gobs and let them run into the holes until it was filled but left it about a quarter inch lower than needed. There was another two to three inches below the hole that was crumbling and I hoped filling that area in as well as a second coating over the hole might stabilize the slab. I waited 24 hours but the patch was still wet, probably due to the 55 degrees in the cellar. I took the bar clamps off and carried the slab upstairs on the board and let it dry another 24 hours. Totally dry, down stairs I went again. Mixed up a second batch and put that second layer over the hole and the crumbling area and immediately took it back into the warmer house to let dry. 24 hours later it was all but completely dry. It was dry enough to check the backside that I was concerned about due to the cracks. It still looked fragile but didn't feel at all "loose". I made a third batch, this time more syrupy. Caution, it quickly goes from syrup to watery. I had to add cement to get it right. I filled small holes on the back and a very thin layer over the bad area and let it sit for another day and a half when I finally had time to reinstall. All of the looseness of the slab was firmed up and it felt solid. My hope initially was that I could get it to hold up until the new one came in. After seeing how well it felt, I thought maybe I could get to the end of the burning system and after a few fires, I'm thinking that if it holds up thru the rest of the winter I'll just leave it alone. If it starts crumbling, I'll have the replacement here and it will be an hour or so project to put the new one in. I loved this stuff!

As I couldn’t find the original refractory boards for my fireplace, I decided to give a try to this product. I used two buckets (50 lbs) of this refractory cement to fabricate four panels. I followed precisely the instructions to have an optimal mix. Poured it into the molds and 24 hrs later the result was pretty awesome. I did a couple of minor cuts with a diamond saw for a perfect fit and it didn’t cracked or chipped off. It feels rock solid. Yes, it is time consuming but for me it was the only solution and probably at a fraction of the price of the original panels. Now the time will show if it was worth it.

Definite learning curve here. Not nearly as forgiving as mortar for brick and block, but a with little practice and a little experience, anyone who can get good results with masonry mortar can enjoy success with refractory cement. Very important to read and follow the instructions, which make it sound like working with this stuff is easier than it really is. For my purposes, which involve building arches from fire bricks to make the roof of a wood stove fire box, I have found it wise to work in small batches. A small batch is so easy to mix it makes no sense to race the pot life clock with a big batch. Note that the bigger the batch the faster it gets hot and sets up. Heat is your enemy here. One thing that really helps is to keep your cement in a cool location before mixing and to use ice water, without the ice cubes. I have found that I can mix equal volumes of sand and cement to get excellent results in terms of bonding and compression strength. No doubt some loss of tensile strength, but perhaps better shear strength. So. Save some good money with a little clean mortar sand. Best if damp enough to hold the shape of a tennis ball size sphere, but if dry, just add a little more water. Avoid really wet sand because this cement really works best if quite dry. Have since done a heat test. Stays hard and strong when heated to glowing yellow. Which is around 2000 degrees Fahrenheit. My small batch recipe is one quart sand, one quart cement, and one and a quarter cups of water. This uses about five pounds of cement. Using cool materials and cold water the pot life is a comfortable 25 minutes from when the water is added to the previously mixed sand and cement. Best to use a mixing tray rather than a bucket as this mixes much more easily and being spread out, is not prone to self-heating. I like the ten gallon tough tote. Which has also proven to be easier to work out of than a bucket. Follow up report: I made a test batch of equal volumes of mortar sand and cement, using the suggested water to cement ratio. After curing and slow heating with a heat gun, I used a propane torch to heat a quarter of a 1 1/4 inch test ball to glowing yellow for a minute. During which time, I poked at it with a utility knife. Could detect no softening and saw no indications of failure. A good idea to test, but go ahead. Be creative.

Like that this sets up fairly fast and holds up pretty well under high fire conditions. Worth the cost.

The directions on the tub are very specific, but mixing 1 quart of water with 12.5lbs of product will not result in the dry consistency required. This mix also sets extremely quickly. They advertise 20-30 minutes working time. In reality, I has 15 minutes from the time water hit the mix until it started setting up. Recommend using a mechanical mixer and working as quickly as possible.