In a previous article, we provided information about how the high performance of calcium aluminate cement is used in various construction chemical applications. In this article, we discuss for you how roads are increasingly constructed using calcium aluminate cements, what the application advantages are and key considerations.
How to Construct Concrete Roads with Calcium Aluminate Cement
Not only does calcium aluminate cement set quickly and achieve high initial strength, but it is also resistant to corrosion. CAC concretes make it possible to use concrete in situations of excessive wear from industrial vehicles and in situations subject to spills of mild acid. Resistance to thermal shock is also important in some situations, such as in foundries and cryogenic facilities.
Calcium aluminate cement-based repair concrete (Figure 1) was used in an area of about 100 m2 at the Çimsa calcium aluminate cement production plant in Mersin. The goal in this project was to achieve 30 MPa in 4 hours to satisfy the need for initial strength in projects that require rapid concrete pouring such as factories and city roads.
Figure 1. Çimsa Concrete Road Construction
Three different concrete designs were prepared in this study and the detailed recipe design is provided in Tables 1 and 2.
The design of Experiment 1 used the following additives for each cubic meter: 120 grams of retarder and 520 grams of plasticizer. In Experiment 2, an additional 600 grams of polypropylene fiber per cubic meter was also included with the other additives. In the first blend, there was a loss of initial strength under pressure due to the additives even though the setting time was longer. The fiber was added to the concrete blend due to the risk of cracking.
In the concrete blend used in Experiment 3, the additives were removed from the recipe to enhance early strength gains. In this study, rapid hardening was observed, and the workability time was shorter than expected. In order to prevent problems that might occur in the concrete mixer, fiber and water were added to the concrete when it was poured.
Concrete Road Construction with Calcium Aluminate Cement: Results of the Experiment
In conclusion, the additives delayed setting time in the calcium aluminate blends, so they increased workability time. Therefore, it can be reliably used in applications that require workability and where there is no expectation of initial strength. In concrete applications that require early strength, the product must be used without additives. Workability time is shorter in applications where early strength is expected. As is the case with all concretes, in experiments with concrete using aluminate cement, one of the most important issues is curing, which becomes more relevant as initial strength increases. It is also essential that the curing process commence early.
Sample recipes:
| Materials | Experiment 1 | Experiment 2 | |
| Amount of CAC (kg/m3) | 400 | 400 | |
| Amount of water (kg/m3) | 160 | 160 | |
| Water/Cement | 0.40 | 0.40 | |
| PP fiber (kg/m3) | 0 | 0.6 | |
| Additive 1 | 1.2 | 1.2 | |
| Additive 2 | 5.2 | 5.2 | |
| 0-4 Aggregate (kg/m3) | 938 | 938 | |
| 5-12 Aggregate (kg/m3) | 357 | 357 | |
| 12-22 Aggregate (kg/m3) | 585 | 585 | |
| Initial Slump (cm) | 12 | 10 | |
| Strength under Pressure (MPa) | 6 hours | 0.0 | 0.0 |
| 24 hours | 29.7 | 25.8 | |
| 2 Days | 31.2 | 33.1 | |
| 7 Days | 35.9 | 37.1 | |
Table 1 CAC concrete recipe design with additives
| Materials | Experiment 3 | |
| Amount of CAC (kg/m3) | 400 | |
| Amount of water (kg/m3) | 188 | |
| Water/Cement | 0.47 | |
| PP fiber (kg/m3) | 0.6 | |
| 0-4 Aggregate (kg/m3) | 940 | |
| 5-12 Aggregate (kg/m3) | 295 | |
| 12-22 Aggregate (kg/m3) | 608 | |
| Initial Slump (cm) | 10 | |
| Strength under Pressure (MPa) | 6 hours | 30.2 |
| 24 hours | 33.4 | |
| 2 Days | 37.9 | |
| 7 Days | 45.1 | |
Table 2 CAC concrete recipe design without additives
Note: The pressure strength values provided above are the strength of 15×15 cm3.
What are the Advantages of Road Construction with Calcium Aluminate Cement?
The need for initial strength in repair concretes has been established in recent years. The first example of these special concretes was successfully implemented in an area exposed to high temperatures at the steel plant in Izmir. Çimsa has also successfully used it in concrete road applications that require high strength and rapid use such as at seaports and airports. The use of calcium aluminate cements in the ready-to-use concrete sector is expected to become more widespread as construction speed and performance requirements increase in the coming years.
References Used
