Save drastically on CO2 emissions with geopolymer concrete

It is not the first application of geopolymer concrete, but it is a very important one. A new quay wall of the Tweede Petroleumhaven in Rotterdam-Pernis was built partly with traditional concrete and partly with this new sustainable concrete mortar. Through monitoring, any differences in performance between the two concrete types can be observed in the coming period. The Port of Rotterdam Authority wants to drastically reduce its own CO2 emissions and wants to achieve this, among other things, by building not only quay walls cementless, but also other concrete structures.

A. Jansen Beton has been involved in the development of geopolymer concrete and its increasingly wide application for some time. "The company is a frontrunner when it comes to recycling waste streams and producing cementless concrete," begins Jan Willem Schlahmilch, Business Unit Manager for A. Jansen Concrete. "In this we work together with other frontrunners, such as SQAPE Technology, which develops geopolymer technologies, and clients like Port of Rotterdam Authority, which dares to invest in sustainable alternatives. For the 150-meter long quay wall of the Second Petroleum Port, two of five sections were constructed with geopolymer concrete, the other three with traditional concrete. Think of it as a test rig: SGS will conduct comparative tests here after 1, 2, 3 and 5 years to gain knowledge."

The quay wall of the Tweede Petroleumhaven was constructed in a wet construction pit by De Klerk Werkendam. The structure consists of tubular piles filled with traditional concrete on which a suspension system was welded. Schlahmilch: "Prefabricated elements of geopolymer concrete and steel fittings were hung on these. De Klerk then filled the resulting gap with geopolymer concrete and sealed it with cover gaps. A. Jansen Beton, as the producer of the concrete, supplied the prefabricated elements under direct orders from the Port of Rotterdam Authority to the maker of the precast elements, Benjamin De Klerk, and to De Klerk Werkendam, which acted as contractor. The precast elements accounted for 130 m3 of geopolymer concrete, filling for 300 m3. By the way, in April of 2023, as part of the testing process, another mock-up was made of the quay wall, in the same composition as the final quay." 

The concrete mixture was developed by SQAPE on the basis of concrete strength class C35/45 and is now named Ramac. Processing is similar to traditional concrete. "With the note that it can be quite sticky if you don't add energy to it," Schlahmilch adds. "Around the pour of the cube it can stick a bit, but with the vibrating seam it flows nicely. Otherwise, mechanically and physically it meets the same properties as traditional concrete. Because of its denser structure, it is even more wear-resistant, suffers less from shrinkage and cracking and is highly resistant to de-icing salts, acids and chemicals. But the biggest plus is the CO2 reduction it provides. By replacing cement as the binding agent with geopolymer based on mineral residues, alkalis and an activator, you can reduce CO2 by up to 85%. Those are numbers you can come up with in this day and age."

Schlahmilch sees a bright future ahead for geopolymer concrete. "Clients like the Port of Rotterdam Authority are ambitious in terms of sustainability and enthusiastic about sustainable concrete. So are parties such as the Department of Public Works and also housing cooperatives with new construction plans. Geopolymer concrete has already been successfully applied in road construction and is now going to find its way into, for example, housing construction. The entire society can thus make great gains when it comes to CO2-reducing measures. Because we all know that the concrete industry is still one of the biggest emitters."