Curb cracking next to Slot Drain
Curb cracking next to Slot Drain
(OP)
We designed a slot drain system adjacent to a curb and gutter along an urban street in front of a high school that was installed 3 summers ago. After the first winter we saw substantial cracking in the curb and gutter next to the slot drain. There are many cracks near the pipe joints as well as cracks at other intervals. Some cracks occur within inches of control joints. There are regular contol joints installed at 10' intervals. The City is now requiring that we remove all of the curb and gutter and re-pour it. We want to be sure to address the cause of the cracking so the problem does not occur again.
Here's some facts: The manufacturer recommended that the curb be poured monolithically with concrete around the pipe for support. The City did not agree and required that we pour the pipe support first, then pour the curb and gutter separately on top. We suspect that there is differential expansion and contraction between the concrete encased slot drain and the curb and gutter. The contractor tried to install a stone dust bond break during construction, but the City inspector would not allow it and it had to be removed.
We think that the bond break was a good idea and should be used for the repair. Altough, we are thinking that masonry sand might be better than stone dust for drainage reasons. Has anyone had a similar experience weith a successful solution or can offer any advice? The construciton detail is shown for reference. Thanks for your help.
Here's some facts: The manufacturer recommended that the curb be poured monolithically with concrete around the pipe for support. The City did not agree and required that we pour the pipe support first, then pour the curb and gutter separately on top. We suspect that there is differential expansion and contraction between the concrete encased slot drain and the curb and gutter. The contractor tried to install a stone dust bond break during construction, but the City inspector would not allow it and it had to be removed.
We think that the bond break was a good idea and should be used for the repair. Altough, we are thinking that masonry sand might be better than stone dust for drainage reasons. Has anyone had a similar experience weith a successful solution or can offer any advice? The construciton detail is shown for reference. Thanks for your help.





RE: Curb cracking next to Slot Drain
RE: Curb cracking next to Slot Drain
RE: Curb cracking next to Slot Drain
RE: Curb cracking next to Slot Drain
RE: Curb cracking next to Slot Drain
Would you recommend a 1" sand layer between the curb and concrete encased pipe as an effective bond breaker?
RE: Curb cracking next to Slot Drain
RE: Curb cracking next to Slot Drain
I would be interested in the QC of the C & G poured. Generally speaking, the curb and gutter prep and placement is usually not on anyones radar until there are problems. While it is routinely the grade line or % slope of gutter, spalling C & G is not that uncommon when constructed incorrectly or allowing loads on it before conc. has attained strength.
Foot traffic around a high school even when school is out might be the culprit. Folks tend to make pours late in the afternoon on hot days....then all go home with no curing or limiting ped. access to freshly poured area.....bicycle tracks in conc. paving/sidewalks comes to mind.
RE: Curb cracking next to Slot Drain
RE: Curb cracking next to Slot Drain
RE: Curb cracking next to Slot Drain