AUTHOR: Marc Robert
Technical Services Director
G3 Quality, Inc.
On April 17, 2020, the State of California Department of Transportation released their revised standard specifications (RSS) to the 2018 Standard Specifications. In this blog, we will talk about additions to Section 40 that will broaden the abilities of a contractor to accelerate this schedule and a means to focus on resolving issues with low beam strength testing.
Opening to traffic when the concrete pavement reaches 550 psi without going to a rapid setting concrete – Section 40-1.03J.
Previous versions of section 40-1.03J have specified under “Protecting Concrete Pavement” that you must protect concrete pavement: “Do not allow traffic on concrete pavement or use equipment on it (1) for 10 days after paving and (2) before the concrete has attained a modulus of rupture of 550 psi based on the Department’s testing…” The inclusion of “for 10 days” prevented contractors from opening the pavement even if the concrete achieved a modulus of rupture 550 psi prior to the 10 days. The only option a contractor had in order to open in less than 10 days was to use a rapid-setting concrete (RSC) at a much greater cost and increased schedule. This created difficulties in working with a fast setting product.
The new 2018 revised standard specification now states in section 40-1.03J 4th paragraph “Do not allow traffic or use equipment on concrete pavement before the concrete has attained a modulus of rupture of 550 psi based on the Department’s testing…” With the removal of “for 10 days” from the 4th paragraph, contractors may accelerate their schedule without using a rapid-setting product and still have a quality product that meets the design criteria of the concrete pavement.
A new Section for Determining Modulus of Rupture from Pavement Cores – Section 40-1.01D(8)(c)(v).
You may have read in our recent blog about how this new section adds a dispute resolution to section 40 that provides guidance to a Resident Engineer. The section allows the Engineer to review low strength beam data, tested by quality assurance, to assist in deciding the best course of action. The process creates a correlation between flexural beam strength and compressive core strength initiated during the test strip or first day of production where 3 flexural beams are taken and broken at 28 days. At 23 days, a set of 3 cores are taken from the area that represents the 3 flexural beams and tested at 28 days. From these 2 sets of compressive and flexural tests, a formula is applied to calculate the equivalent 28-day modulus of rupture.
The cores are continued to be taken from the slab and tested at the ages of 42, 56, 70 and 91 days to give a contractor the ability to test on one of these days, correlating back to the calculated 28-day modulus of rupture. This calculated 28-day modulus of rupture correlated from the cores are then compared to the Q/A acceptance beams to see if it verifies the Q/A results or gives data that disputes the results of those beams. These investigation results will give more data for the Resident Engineer to review and make an engineering decision whether the in-place concrete pavement in question may remain in place.
Both of these additions are to the benefit of the owner, The State of California, and the contractor to help keep projects on an accelerated schedule and with minimum delays due to disputes over whether the in-place concrete pavement should remain. G3 Quality, Inc. is here to provide any further information you may need and how to implement these new changes to your current or upcoming projects. Stay tuned for our next blog when we discuss Section 40-1.01C(4) for mix designs.
For more information, reach out to our Technical Services Director, Marc Robert by email at mrobert@g3quality.com or by phone at 562.321.5561.
At G3 Quality, we are industry leaders who are always embracing change and excellence. Research and strategy are at the forefront of our operation. Our services include quality management, materials testing and inspection, geotechnical engineering, pavement design, and materials designs on infrastructure projects in California. To learn more about how G3 Quality can contribute knowledge, expertise, consulting, and professional services to your project, contact us.