Relating seismic modulus and maturity to strength parameters of portland cement concrete

Several Texas Department of Transportation (TxDOT) districts rely solely on portland cement concrete (PCC) pavements for heavily traveled highways and urban/suburban sections of the interstate. The major design parameter and acceptance criterion for in-place PCC slabs are usually based on the compressive, tensile or flexural strength tests. Nondestructive testing (NDT) techniques based on seismic and maturity to monitor and predict the strength and modulus development of PCC are also currently being investigated. The seismic modulus and the maturity can be related to the strength parameters and static modulus obtained from conventional testing on the molded specimens or drilled cores.; Previous research efforts have demonstrated that the rate of increase in modulus differs from that of either tensile or compressive strength. This is potentially problematic, as it leads to increased stresses in the concrete and may be an underlying cause of excessive horizontal cracking observed in PCC pavements. To investigate this problem, the impacts of different mix proportions and constituents as well as the impact of curing under different environmental conditions on the development of strength and modulus parameters of PCC are investigated. A database, containing results from about 1200 standard cylinders made from fifteen different concrete mixes, subjected to different curing environment has been developed. Preliminary relationships with seismic modulus and maturity as dependent variables for predicting strength parameters and static modulus are proposed in the basis of different mix and environmental parameters.