Infrastructure that is safe, functional and resilient shall be a top priority for any major corporation within the construction sector. Currently, the replacement of unreliable structures is costing taxpayers millions of dollars in repairs and maintenance costs, annually. This problem is correlated to the inability to predict and understand the quality and performance of the concrete structures today. Throughout the years there have been plenty of products and inventions that have tried to solve these issues, but like most systems, they all have their limitations. On this short article, we will compare traditional concrete cylinder ‘break-test’ Vs ‘IoT Sensors’ methods for concrete testing that are being used today.
To make a fare comparison between the two methods, we will focus our attention in three core areas, testing process, speed, and cost, and we will discuss the advantages and disadvantages within each method:
Testing Process & Method:
Concrete Cylinder Break Test Method: Cast-in-place concrete specimens are prepared by the construction materials testing technician (CMT) that comes to the constructions site. The technician is responsible for taking samples of every batch of concrete sent by the ready-mix plant. The specimens are casted and left onsite for field curing, then collected the next day and taken to the CMT Lab for testing. Usually the testing process involves breaking a cylinder or two at days 3, 7, 14 and 28 to determine the concrete strength for each specimen and then correlate the PSI results to the concrete placed on the structure onsite. This method for testing can be found under ASTM C39 standard for concrete testing using cured cylinders. The advantage of this method is that is well-known and accepted worldwide because it has been around for hundreds of years. On the contrary, a disadvantage of using this method is that it takes time and manual effort to get results back to the project personnel in the field waiting for these results. In most cases, 2-3-days to get back these results can be a little too late if a quality problem arise or an urging decision needs to be made.
CMT repetitive casting cylinders onsite
Compression machine breaking concrete cured cylinders
IoT Sensors ‘SensyRoc ™’: This method consists of embedding wireless IoT sensors in fresh concrete. The sensors can be easily tied to the rebar or formwork prior the placement of the concrete and/or during the pouring process. These sensors record the in-place temperature of the concrete to determine the quality and strength of the concrete in real-time. The data collected by
the sensors is recorded and analyzed using the ASTM C1074 which is testing method for determining the concrete strength based on the principal that concrete strength is directly related to its hydration temperature history. One of the biggest disadvantages of this method is that it is fairly new methodology in comparison to the cylinder break test method, therefore its adoption and usage can be limited to early adopters and construction companies seeking new systems to improve their project efficiency. That said, the advantages of deploying such method into construction projects is that concrete results can be obtained quickly because the data is analyzed and transmitted instantly to any mobile device through an App. Having this crucial information reduces construction waiting time by multiple days, and decreases the potential for errors by the continuous monitoring of the fresh concrete. Additionally, it allows users to make quick and informed decisions during the construction process, which improves project efficiency and saves money.
SensyRoc ™ Sensor is easily installed on rebar before the pouring of the concrete.
Concrete data (Temperature & Strength) is received instantly through our mobile app.
Break Testing Method: This traditional method is terribly and slow labor intensive. It usually requires two-three days for the collected specimens to be fully cured before performing the break test. Additionally, results maybe affected by improper casting, handling, curing, and testing of the cylinders which could results in low breaks. Low breaks are a major hurdle because it means that additional ‘coring’ testing must be done onsite, which is a huge headache for all parties involved within a project. It can cost thousands of dollars in lost time and money, no one wins if this event occurs. Another disadvantage of this method is that in reality temperature history for cylinders may differ due to curing conditions—cylinders are cured in a control lab environment—causing a different rate of strength gain in comparison to the concrete placed in the field.
IoT Sensors ‘SensyRoc ™’: The sensors continuously record the measured temperature and the results can be downloaded automatically onsite. Instant results allow users to understand temperature & strength developments in real-time, making quicker decisions accordingly, and reduce construction waiting time by several days. Additionally, results can be analyzed and easily shared among team member for better logistics implementation during the construction process. Ultimately saving time and money for all.
Break Testing Method: Aside from being a very slow process, this method is very costly as well. There is a technical cost associated with having a technician from onsite to cast the cylinders. Additionally, there is another cost associated with the transportation and delivery of the specimens. And lastly, the cost for performing the testing and preparing the results. The lack of an accurate estimation of the strength at early stages result on longer waiting time before performing the next action during the construction process (e.g. stripping formwork and/or post-tensioning). These delays can be costly as well when working on a project with a set completion date and additional financing may be required due to late completion of the project.
IoT Sensors ‘SensyRoc ™’: The sensors required little to no efforts at all during the installation and this task can be done by any worker onsite. In average, sensors can predict the specified compressive strength of the concrete within 10-24 hours after the placement of the concrete. This results on saving two-three working days per pour since the results are obtained within a day in compression to the three days that it takes a CMT lab before sending the results back. Furthermore, there is a significant financial savings as results of early completion of the projects.
All in all, both methods have their advantages and disadvantages that shall be taken into consideration; however, one can say that IoT Sensors ‘SensyRoc ™’ far outweighs the benefits provide by traditional concrete break testing.