Many materials testing activities are used to evaluate when certain construction activities can move to the next stage. Soil compaction testing of fill materials determines if additional fill can be placed or if paving or foundation work can begin. Concrete compressive strength testing dictates whether post-tension cables can be stressed or concrete formwork can be removed. Failing tests or insufficient test results can delay construction activities and impact the overall construction schedule.
To assist our clients, Terracon focuses heavily on getting critical information to the project team quickly so a timely decision can be made. Our use of technology to efficiently collect and report our test results is key in making this happen. We also use technology to support how testing is performed to further create efficiencies in the construction schedule and accelerate the decision-making process. One area where we do this is in the testing of field cured cylinders for concrete form removal or post-tension cable stressing. Terracon can use the maturity meter method (ASTM Standard is C 1074 “Standard practice for estimating concrete strength by the maturity method”) to provide real-time data to be used to assess when form removal or stressing operations can occur or be used to augment when field cured cylinders should be tested.
We have found that with proper application, use of a maturity meter has the potential to save an average of one day per impacted concrete pour on typical commercial projects. In some cases, this has resulted in reducing a project schedule by months and saving thousands of dollars in construction costs.
By taking time prior to the start of concrete placements or during initial concrete placements to use the maturity meter on initial batches of the approved concrete mix, maturity index values can be correlated with the compressive strength of early-age cylinders. This in turn provides the baseline for future placements and the critical decision making process of when to remove formwork or when to stress post-tension cables by the construction team in a timely manner.
The initial costs in trial batches and correlation testing to develop the maturity curves and the actual maturity monitoring during placement is a minimal and worthwhile investment that can be quickly recovered. The form removal and stressing decision process, the significant construction schedule time savings, as well as reduction in the number of cylinder test specimens required per the project, all result in accelerating the construction of concrete construction projects.
Using the maturity meter method for early strength assessment can provide more accurate data in assisting in assessing when:
In addition, maturity meter can also be used to measure:
Jon Doudna is a project engineer in our Denver office. He has 31 years of experience in construction engineering inspection and design including materials testing, field investigations for construction defects and materials distress, and construction observation supervision. Jon has managed residential, commercial, education, medical, and public infrastructure improvements.