APRIL 18, 2001 - Concrete Cracks

Speaker: Don Taubert

Our presenter at this past meeting was Don Taubert. Don had numerous slides showing what the different types of concrete cracks indicate. He also showed different methods used to cool down the concrete mix during transport, including adding shaved ice and even liquid nitrogen to the drum. The expense of doing this was obvious when he said the temperature of the bulk materials used to make concrete stays at a fairly constant temperature of 150 degrees F!

Don also talked about different methods for curing slabs in warm weather such as fogging (to increase the relative humidity), using poly sheets (provided they remain very flat on the slab) and chemical cures. He cautioned that chemical cures typically degrade about 7 to 10 days after application. Don also promoted using more fly ash in the concrete mix, up to 40% (the current local standard dictates only 20% max).