I currently have a gravel driveway that I would like to upgrade to concrete. It has had several layers of gravel over the decades and been driven on for at least 50 years. Any concrete slab on grade I have ever designed has always included a gravel base over the subgrade. However, I am thinking...
The concrete will be used for a base slab of an oxidation ditch at a wastewater plant. The contractor will be getting trucks from both plants during the slab placement. It will be a large pour and 1 plant will not be able to keep up with it hence his proposal to use 2 plants. We have told him...
We have a large concrete placement planned and the contractor wants to use 2 different batch plants. The issue is each plant has a different proposed mix. Each mix by itself would be acceptable but I don't know if it would be a good idea to mingle the 2 mixes. One mix proposes the use of Type 2...
The PADOT min. embedment is 1'-0" unless it is a single row of piles in which case it is 1'-6". Probably because I have been using that standard for over 30 years that 6" seems skimpy.
Just curious but did the contractor make a concrete submittal and, if he did, did it show entrained air? Was there a clerk of the works or inspector on the job when the concrete was delivered?
I pretty much agree with everything that bridgebuster has told you. Only thing is that some states, PA for example, do not require Team Leaders to be PEs. I spent several years inspecting bridges in NY and PA and absolutely loved it. I always worked for consultants and not a DOT which meant you...
Our firm designs a lot of below grade tanks for wastewater plants and we quit using the ground water relief valves over 20 years ago after we actually had a valve malfunction and a large clarifier floated about 2 feet out of the ground. We now use the tank weight exclusively to counter act the...
The company I work for does a lot of WWTP work involving the design and construction of concrete tanks and we never put vapor barriers below the tank slabs. It has never resulted in a problem of which I am aware.
Listen to your contractor. There is a chance of blistering and/or delaminations when you hard trowel air entrained concrete. See ACI 302.1R 5.7.1. I would recommend keeping the air and either eliminating the trowel finish or minimize your water content(slump) and delay the troweling until all...
I cannot find our office copy of the 1993 AASHTO PDG and have been asked to do a small pavement design. What I really need is Figure G.7 and Figure G.8 from Appendix G. If someone could scan them for me I would really appreciate it. Thanks!!
I am doing a pavement design and cannot find our 1993 AASHTO Pavement Design Guide. What I really need is Figure G.7 and G.8 from Appendix G so if someone could scan them for me I would really appreciate it. Thanks!
Using active soil pressure is not being conservative. At rest pressures are usually greater than the active pressures plus, as already mentioned, saturated soil may need to be considered.
We really need to know what level of service the road will provide. We seldom use approach slabs on low volume roads. You will get some settlement but it may be more cost effective to add more road material when the settlement becomes objectionable than pay for approach slabs. In addition to the...
I would like to thank everyone for their suggestions. We solved the problem by eliminating the tendon access pockets and the staged construction. The contractor and the P/S plant both feel they can install the tendons and post-tension the beams without staging the construction.
It is at a WWTP but will not be in contact with any wastewater. It houses sludge pumps in the basement with dry storage on the first floor. We do, however, use type 2 cement on all structures.
