Cement mortar being mixed with water
Dry-mixed mortar only gets its water at the site, and in those two minutes of mixing the foam all comes up: the wall is left covered in pinholes and strength falls with it. The workers assume the water-cement ratio was not controlled, but in fact the foam came with the formulation.
Chemi Tech makes defoamers for powder formulations such as dry-mixed mortar and skim coat powder, drawn from the defoamer KM-955 series. How a grade is matched depends on the cementitious system of the powder, the water addition and the mixing method. KM-955 is in powder form and comes in a silicone and a silicone-free grade: it is dosed together with the other powders during dry mixing, so there is nothing to dissolve separately and no liquid to add later, and it only takes effect at the water addition and mixing stage. Chemi Tech customises against the powder formulation and the mixing process and recommends a powder defoamer that fits.
Advantages of Chemi Tech Defoamers
Chemi Tech defoamer KM-955 series is in powder form: it goes straight into the mixer during dry mixing and blends with the cement and sand, with no liquid dosing line to open. The point of action is precise as well — the foam is pressed down the instant water goes in and mixing starts, and nothing else has to be added at the construction site. It comes in a silicone and a silicone-free grade, so a formulation sensitive to silicone can run the silicone-free grade and leave no hidden problem on a decorative surface. It disperses evenly, too, with no compatibility issue between powder and powder, so there is no local overdose. Storage and handling are simpler as well: a powder keeps better than a liquid and can come in with the raw materials.
Industry Pain Points and Solutions
When mortar foams on the addition of water, the first thing to go wrong is air entrainment in the mixing stage. The surfactant and the cellulose ether in the dry powder swell as soon as they meet water, two minutes of high speed mixing beats air into the paste, the density of the paste falls with it, and it trowels noticeably light. Chemi Tech's approach is to put the powder defoamer in at the dry mixing stage, so the suppression capacity is distributed evenly with the powder.
The problem that follows is pinholes on the wall. If the bubbles in the paste are not knocked down, they burst at the surface after trowelling into a spread of pinholes, and a high-end finish will not pass inspection. Chemi Tech defoaming powder can be added at the mixing and the floating stage: knock the foam down in the mixing stage, and bring the air content of the paste down before it goes on the wall.
The last point is that topping up cannot save it. Sprinkle more defoamer on site once the foam is noticed and the powder will not mix evenly; a local overdose hurts the strength instead. Chemi Tech defoamers clear these troubles at the root — the accuracy of the dry-mix ratio and the coverage of the two grades are the first task we verify.
Typical Conditions and Verification
Customer: a dry-mixed mortar enterprise in Henan, applying it to the dry-mix production line for rendering mortar and cement mortar.
The cement mortar powder from this plant foamed heavily once it was mixed with water at the site, the cured product had an uneven surface, customer satisfaction fell off sharply, and the after-sales team drove out to sites one trip after another. The solution offered by Chemi Tech defoamer was: against the cementitious system and the water addition, KM-955 silicone-free grade was dosed directly by ratio to the dry powder weight. Since KM-955 went in, the density of the mixed paste at the site has improved markedly, the pinhole defects after trowelling are gone, and customer satisfaction has risen substantially.
Frequently Asked Questions
Mixed into the dry powder, will the powder defoamer affect the strength of the mortar?
There are cases where it does: some chemistry holds the foam down and slows the setting of the cementitious system with it. The KM-955 Chemi Tech supplies to mortar plants has been compared for strength and setting time against the dry-mix ratio, and at normal dosage neither item drifts. The dosage is controlled at a small proportion of the total powder weight, and Chemi Tech will give the addition window for your formulation.