9 sack mix is a concrete terminology......basically means that there are 9- 94# bag of Portland cement in each cubic yard of concrete. That is a LOT of cement. A typical commercial mix is only a "6 bag" mix and will have a yield strength of 3000-3500psi when properly cured. You mentioned putting wire reinforcement in the top coat............Wire is not going to prevent it from cracking.........the ONLY thing that it is going to do is stop it from SEPARATING once it cracks. If you ANYONE EVER tells you that they can prevent concrete from cracking by putting wire or fibermesh in the concrete............tell them that you dont need their services!
Pouring concrete is THE ONLY job that I have ever had that you cant walk away from once you start. As we used to say, "when the mud hits the ground, its all Asses and Elbows" I have been on the receiving end of several HOT loads and I can tell you from experience, it is a HANDFUL for someone that KNOWS what they are doing!!
I have been in a lot of different aspects of the concrete business from the batch plant to putting it on the ground........................Dont miss it at ALL.
Here is a little story to make you feel a little bit better. Back when I was probably 20-21 years of age I was working with my step dad in his concrete construction business. Well Hank Jr came to town on a Thursday night and I BEGGED for them to loan me the money to go to the concert ( I was broke because it was mid week.....lol) They agreed that I could go as long as I promised to roll out of bed when the alarm went off (I was living at home at the time) and be ready to roll out on time. Well I went to the concert with EVERY intention of being a good little boy and being home before MiDNIGHT..............well as we all know, all good intentions usually go hairwire. I ran into a female friend at the concert and she had a FIFTH of Brass Monkey hid in her purse. Needless to say, by the time the concert was over, we were all feeling PRETTY DARN GOOD. After the concert was over, we decided to hit a party at a friend of mine's house, that was a HUGE mistake. Before I knew it, it was 3am! I finally got in the bed about 4 and the alarm went off at 6. Well as if that werent bad enough, as I was leaving the house, the step dad gives me an address and tells me that the concrete will be there in about 30 minutes. I roll up on the job and find about a 4500 square foot house slab staring me in the face. It took us a couple of hours to get the concrete on the ground and to the point that we could sit back and wait on it for a little bit before we put the troweling machine on it. After we got it laid down, the old man loads up ALL OF THE HELP but me and one of the other finishers and says........"See ya at the house tonight" This would have been bad enough in the cool months of the year.............but no.......this was in July or August. Needless to say, I was one WORN OUT A$$ when I got home that night about 9pm. For those of you that have never been around fresh concrete, it sets up by means of a CHEMICAL REACTION and not by the heat in the air. Once it starts to set, there is NO STOPPING IT. Well, that chemical reaction produces a great deal of heat and if you are on top on that concrete slab in the middle of August, you are getting BAKED from the top by the sun and from the bottom by the concrete! Moral of this story................NEVER EVER EVER got to a concert and stay out late when you are scheduled to pour concrete the next morning!