Why con­crete and tex­tiles? As a design­er at heart, while Ng was pur­su­ing her PhD about 15 years ago, she worked on a façade that resem­bled tex­tile pat­tern­ing for a cloth­ing company’s head­quar­ters in Chi­na. Lat­er at the Uni­ver­si­ty of Michi­gan, her inter­est in a larg­er role for tex­tiles in build­ing mate­ri­als con­tin­ued. Ng’s research draws on the exper­tise of many dif­fer­ent fields, from mate­r­i­al sci­ence and engi­neer­ing to con­struc­tion log­ic and archi­tec­tur­al design, and she has worked col­lab­o­ra­tive­ly with her stu­dents, engi­neers, sci­en­tists, and even a CNC knit­ting expert. Ng explains, ​“It’s excit­ing to cre­ate sus­tain­able prac­tices that reduce con­struc­tion waste in the form­ing of the mate­r­i­al. The result is a more resilient con­crete that will last longer with the least amount of main­te­nance, and final­ly that might even lessen the amount of work need­ed for such construction.”

The Knit Cast­ing project, for exam­ple, is a recent col­lab­o­ra­tion with Sean Ahlquist, a CNC knit­ting expert, and Evgueni T. Fil­ipov, from the Civ­il and Envi­ron­men­tal Engi­neer­ing Depart­ment at the Uni­ver­si­ty of Michi­gan. It explores the use of CNC man­u­fac­tured knits to pro­duce vol­u­met­ric tex­tile form­work for cast­ing glass fiber rein­forced con­crete. The research inves­ti­gates how a func­tion­al­ly-grad­ed knit form­work can be used as a ful­ly seam­less sys­tem to cast concrete.

The advan­tage of using a knit­ted tex­tile as form­work is that it uses a min­i­mal amount of mate­r­i­al in com­par­i­son to tra­di­tion­al wood or steel form­work. This means that you can get com­plex geome­tries and tex­tures that would oth­er­wise be dif­fi­cult to achieve with tra­di­tion­al flat stock mate­ri­als. Not only does it reduce the labor and time in the mak­ing of the struc­ture through automa­tion, it also dras­ti­cal­ly reduces mate­r­i­al waste for con­struc­tion. The knit form­work is light­weight, trans­portable and can be deployed for cast­ing any­where. ​“It uses less con­crete and cement as a mate­r­i­al,” Ng says. ​“And so, there’s a lot of plus­es when we start rethink­ing how we cast concrete.”

The research team has come up with sev­er­al knit types of vary­ing stretch that cre­ate diverse form­works. By inflat­ing the knit with con­crete, you end up giv­ing both the con­crete and the soft tex­tile it’s final form. ​“In the end, we don’t know the final form until the knit is cast,” says Ng. In one exam­ple, the team used a sin­gle jer­sey knit with poly­ester that could be removed quite eas­i­ly after form­ing the con­crete shape.

The researchers have devel­oped sim­u­la­tion mod­els to bet­ter under­stand the effects of the knit in rela­tion to the hydro­sta­t­ic pres­sure of the con­crete. They have also exper­i­ment­ed with dif­fer­ent mate­ri­als. In one case, they used acrylic which was heat­ed and vac­u­umed over a dia­grid cast, cre­at­ing a com­plete seal to the pan­el and result­ing in a space-age bub­ble-like win­dow. Ng hopes to be able to devel­op dif­fer­ent ways to assem­ble the prod­ucts so that they can be put togeth­er either on- or off-site.

“Our built envi­ron­ment is com­posed of dif­fer­ent mate­ri­als, which means that instead of just using one mate­r­i­al like 3D print­ing, we could use sev­er­al mate­ri­als,” Ng says. ​“As you’re cre­at­ing an inte­ri­or or exte­ri­or wall pan­el, you could cre­ate views out of it, using not only con­crete but also glass. The chal­lenge is fig­ur­ing out how to do this at scale.”