I am doing a senior project on rapid setting mortar for a 3D

I am doing a senior project on rapid setting mortar for a 3D printer. I was wondering if you could think of any materials that could be added to the mortar (after being poured) that would reduce the setting time?
Thanks for your help,
Jordan Perez

Solution

Material added to Mortar for reducing Setting Time are -

Water reducing admixtures (WRA) - .

Mainly the fresh properties of concrete by reducing the amount of water used by 5% to 12% while maintaining a certain level of consistency, measured by the slump as prescribed in ASTM C 143-90. The use of WRA may accelerate or retard the initial setting time of concrete. The WRA that retards the initial setting time more than three hours later is classified as WRA with retarding effect (Type D).WRA has been used primarily in hot weather concrete placing, pumping.

Retarding admixtures -

here are two kinds of retarders, defined as Type B (Retarding Admixtures) and Type D (Water Reducing and Retarding Admixtures). The main difference between these two is the water-reducing characteristic in Type D that gives higher compressive strengths by lowering w/cm ratio.

Retarding admixtures are used to slow the rate of setting of concrete. By slowing the initial setting time, the concrete mixture can stay in its fresh mix state longer before it gets to its hardened form. Use of retarders is beneficial for:

Retarder can be formed by organic and inorganic material. The organic material consists of unrefined Ca, Na, NH₄, salts of lignosulfonic acids, hydroxycarboxylic acids, and carbohydrates. The inorganic material consists of oxides of Pb and Zn, phosphates, magnesium salts, fluorates, and borates. Commonly used retarders are lignosulfonates acids and hydroxylated carboxylic (HC) acids, which act as Type D (Water Reducing and Retarding Admixtures). The use of lignosulfonates acids and hydroxylated carboxylic acids retard the initial setting time for at least an hour and no more than three hours when used at 65 to 100 ^oF.

Superplasticizers (High Range Water reducer) - ASTM C494 Type F and Type G, High Range Water Reducer (HRWR) and retarding admixtures are used to reduce the amount of water by 12% to 30% while maintaining a certain level of consistency and workability (typically from 75 mm to 200 mm) and to increase workability for reduction in w/cm ratio. The use of superplasticizers may produce high strength concrete (compressive strength up to 22,000 psi). Superplasticizers can also be utilized in producing flowing concrete used in a heavy reinforced structure with inaccessible areas.

The use of superplasticizers does not significantly affect surface tension of water and does not entrain a significant amount of air. The main disadvantage of superplasticizer usage is loss of workability as a result of rapid slump loss and incompatibility of cement and superplasticizers.