Common Problems And Solutions Of Refractory Mortar

1.Adopt split water‑adding process: add 80% of water first for mixing, stand for 2 min, then add the remaining water.

2.Cover mixed refractory mortar with wet cloth to shorten exposure time.

3.Add 0.2%‑0.5% hydroxypropyl methyl cellulose (HPMC) water‑retaining agent.

4.Avoid construction during high‑temperature noon hours.

1.Control single‑batch mixing quantity to ensure complete consumption within 20‑30 min.

2.Sprinkle water in advance to moisten the construction base surface on hot days (no free water).

3.Set up temporary sun‑shade and wind‑shield shelters.

1.Mix with warm water at 20‑30℃; pre‑heat refractory mortar to 10‑15℃ in advance.

2.Reduce water addition by 2%‑3% (not lower than the standard lower limit).

3.Add 0.5%‑1.0% sodium aluminate setting accelerator for cement‑based refractory mortar.

4.Raise the temperature of construction area above 5℃, and cure by covering with rock wool quilts.

1.Set up thermal‑insulation shelters for winter construction and avoid open‑air operation.

2.Strictly prohibit mixing with cold water or ice‑cold water.

3.Acid setting accelerators are forbidden for magnesia‑based refractory mortar; select special composite setting accelerators instead.

1.Remove loose parts at slightly cracked areas, then repair and compact with refractory mortar of the same grade.

2.Demolish and re‑lay for large hollow areas, and ensure the base surface is clean and dry.

3.Cover for moisture retention during curing to avoid sudden temperature changes.

1.Strictly control water addition within the standard range; over‑watering is strictly prohibited.

2.Thoroughly clean floating dust, oil stains and loose layers on the base surface before construction.

3.Curing time shall be no less than 24 h at ambient temperature, and no less than 48 h under low‑temperature conditions.

1.Chisel the spalled area into a dovetail‑shaped groove (wider inside than outside), remove residues and apply repair mortar in layers.

2.Re‑establish the furnace baking curve, and hold soaking at low temperature (50‑100℃) for 6‑12 h for moisture removal.

3.Ensure the mortar joint thickness is controlled within 2‑3 mm with filling rate no less than 90%.

1.Select refractory mortar of matching grade according to service conditions (acid / alkaline / neutral).

2.Rapid temperature rise is strictly prohibited during furnace baking; the heating rate shall be controlled at 50‑100℃/h.

3.Tap and compact lightly with wooden mallet during bricklaying to avoid excessively thick or void mortar joints.

1.Strictly control the standing time after mixing to no more than 10 min; do not use if time is exceeded.

2.Discard hardened and failed refractory mortar directly; re‑mixing with added water is forbidden.

1.Mix siliceous refractory mortar for immediate use; control single‑batch mixing quantity to be consumed within 10‑15 min.

2.Avoid excessively high rotating speed during mixing, to prevent accelerated hardening caused by excessive friction temperature rise.

1.Remove cracked sections and re‑apply with formula of lower water dosage.

2.Prevent direct contact between magnesia‑based refractory mortar and fire‑clay / high‑alumina bricks; install isolation layers.

1.Control water addition of magnesia‑based refractory mortar within 10%‑15%; over‑dosage is strictly prohibited.

2.Acid admixtures are forbidden; do not mix with cold water.

3.Keep good thermal insulation for winter construction to prevent freezing during curing.

1.Add an appropriate small amount of additional water (not exceeding the upper limit), and extend mixing time to 3‑5 min.

2.Wet tools with water in advance to reduce adhesion.

1.Mix strictly in accordance with the standard water‑material ratio to ensure uniform consistency without dry agglomerates.

2.Allow 2 min standing time after mixing for sufficient water penetration into aggregates.