Purpose
To ensure uniform blending of chemical admixture to improve compaction, reduce water demand, accelerate setting time, and eliminate micro-cracks in hollow and solid blocks.
Equipment & Parameters
-
Mixing Equipment: Heavy-duty Pan Mixer (Planetary or Counter-Current preferred).
-
Target Dosage: 400g to 500g per 50kg of cement (0.8% to 1.0% by weight of cement).
-
Addition Point: Pre-dissolved in the secondary mixing water. Never add directly to dry cement.
1.Dry Material Blending:Duration: 1 to 2 minutes.Charge the pan mixer with your dry raw materials in order: M-Sand dust, Fly Ash, and Cement. Dry mix them thoroughly for 60 to 90 seconds until the color of the bed is completely uniform. This ensures the cement particles are well-distributed before hydration begins.
2.Prepare the Chemical-Water Solution:Parallel Step.Weigh the exact required amount of chemical admixture (400g to 500g per bag of cement being used in the batch) using a digital scale. Pour this measured quantity into a dedicated bucket containing roughly 50% of your total required batch water. Stir it briefly to ensure complete dissolution.
3.Initial Water Addition:Duration: 30 seconds.Add the first 50% of plain water directly to the running dry mix. Let it spin for 30 seconds. This dampens the aggregates and initializes the primary hydration of the cement without flooding the mix.
4.Admixture Solution Injection:Duration: 1 to 2 minutes.Slowly pour the pre-dissolved chemical-water solution into the running mixer. Allow the pan mixer to run for an additional 60 to 90 seconds. The plasticizing molecules will immediately begin dispersing the cement particles, making the mix noticeably more fluid and workable without adding extra water.
5.Consistency Check & Discharge:Final Step.Check the consistency of the semi-dry mix. It should hold its shape perfectly when compressed tightly in your palm ("ball test") without bleeding water or crumbling apart. Discharge the homogenous mix immediately to the hopper of the block-making machine.
Critical Quality Control Rules
The Golden Rule: Never dump the chemical admixture directly onto dry cement or dry fly ash. Dry cement will instantly absorb the liquid chemical, creating highly concentrated clumps that won't disperse during mixing. This leaves some blocks with too much chemical (causing cracking or delayed setting) and others with none.
-
Moisture Calibration: Because the chemical admixture improves workability, you will need less total water than a standard manual mix. Reduce your initial water addition slightly and let the chemical do the work of making the mix fluid under the machine's vibration.
-
Vibration and Compaction: Ensure your vibro-hydraulic block machine runs its full vibration cycle. The admixture is engineered to respond to mechanical vibration, liquefying just enough under pressure to pack tightly into the molds, ensuring sharp edges and zero honeycombing in your hollow blocks.
-
Batch Scale Guide:
