BAHÁ’Í WORLD CENTRE — After tireless and meticulous effort, a much-anticipated milestone has been reached—the construction team has completed the pouring of the concrete for the trellis of the Shrine of ‘Abdu’l-Bahá. This marks not only the end of one of the project’s most technically challenging aspects but also the culmination of work on the Shrine’s concrete structure.

The team had initially planned to pour all the concrete for the trellis—the intricate roof structure that now spans the central plaza and edifice—all at once. However, in mid-August, they decided to first pour the high-quality white concrete into the north and south soffit areas.

The white architectural concrete, with its textured surface, is chosen for its visibility from the plaza, while the grey concrete remains unseen.

On the evening of Sunday, August 27, the team initiated the pouring of the grey concrete, a task that continued for 19 hours non-stop. Throughout the night and into the following day, it was necessary to ensure a constant stream of concrete during that period to achieve a monolithic structure with no joints.

Khosrow Rezai, the project manager, explained that this “required four pumps at the same time strategically placed in different locations.”

Amnon Cohen, the general contractor, described the complexity of this task: “It was a huge challenge to coordinate the four pumps so that they didn’t interfere with each other.”

To manage this, the trellis was segmented into four quadrants, each with a dedicated team. “Every team had a pump, and a sector to deal with,” Mr. Cohen further elaborated, “and there was a special way to cast the structure because the concrete had to be cast in a way that the curves and the corners of the EPS mold could be penetrated.”

Another challenge was ensuring a steady flow of concrete at each pump. Mr. Cohen explained: “We had to coordinate all of the trucks that enter the gate so that they would know where to go, which pump to go to, and to make sure that there were not too many trucks at one pump and too few at another. It was always truck after truck at each pump, and the amount of concrete was balanced between them, so that the ceiling could be cast homogenously.”

To ensure an uninterrupted supply of concrete, the team coordinated deliveries from four different plants. This approach was necessary because the required volume could potentially surpass what any single concrete plant might produce in a 24-hour period. Another consideration was minimizing the impact of traffic delays from any given plant. After consulting with the concrete companies, the team selected a day when they anticipated the least traffic, and minimal potential for delays.

Mr. Cohen described how the team had prepared for every situation: “We had spare equipment for everything, even a concrete pump. We organized ourselves very well so that there was nothing that could surprise us. We made a checklist of all the critical failures that could happen, and we made a plan.”

The spirit on site was charged with anticipation and excitement throughout the process. On Monday morning this week, Mr. Cohen described how everyone was feeling:

“We achieved our goal. So, everybody is very, very happy, even if they are tired. And the spirit on the site is very unique. For four years, something in the air here, on the site, makes people want to succeed, want to do the best job that they can. They see that this is a unique structure that you can create once in a lifetime.”

Rafi Anunu, principle structural engineer, described some of the unique challenges of working on this project:

“All the buildings that we usually design are built to last for 50 years. This building is designed to last hundreds of years. So this needs a different mixture of concrete. It means that the minimum diameter for the rebar is larger. Everything is different. This is not the same as other buildings.”

The concrete of the trellis will now cure for a minimum of 30 days before the formwork underneath it is removed, revealing the completed roof structure for the first time.

Meanwhile, work has already begun to complete the east berm, now that it is no longer needed as a staging area for pouring the concrete. Work is also moving ahead swiftly on the ‘Akká Visitors’ Centre, with its structure now complete and work beginning on the interior.

In the video below, Mr. Rezai describes the next steps that will follow the completion of the concrete structure of the Shrine.

The images below offer a glimpse into the intensity of work involved in reaching this major milestone.

Late Sunday afternoon, the concrete trucks are just beginning to pour the grey concrete. The city of ‘Akká can be seen in the distance.

Concrete trucks arriving on site to ensure a constant supply to each of the four pumps.

A concrete pump on the base of the east berm.

The sun sets on Sunday evening with work fully under way to cast the roof structure. The base of the east berm is used as a staging area for two of the concrete pumps.

Work continues as the sun sets.

At dusk, powerful lights illuminate the trellis.

Trucks continue to assemble on the base of the east berm after dark.

A concrete pump in the north plaza.

Facing west, the city lights of ‘Akká shine in the distance.

Grey concrete is pumped into the EPS formwork.

Trucks continued to arrive throughout the night, ensuring a constant supply of concrete to each pump.

Concrete pumps and trucks can be seen assembled on the base of the east berm.

The work continues as morning approaches.

The concrete pour is in its final stages as the sun rises.

As morning wears on, the center of the roof structure is the only section remaining to be poured.

The concrete is leveled in the center of the trellis.

A series of images showing the different stages of constructing the trellis, beginning with building the EPS formwork and ending with the concrete being poured into the forms.

Light from the setting sun illuminates the completed trellis on Monday evening.

The roof is now cast.