Robomatic Hollowcore Concrete Wall Panels
Robomatic wall panels are extruded non-load bearing concrete hollow core wall panels manufactured in fully automated machines. These wall panels are factory-produced using lightweight concrete made of manufactured sand, crushed stone aggregate, and Ordinary Portland cement. The concrete is extruded and cut while still wet to the requisite length. Curing and sealing are followed for 24 to 48 hours by stacking and palletizing after which the walls are watered and cured for a further period of 7 to 8 days. After 15 days the panels are ready for transportation to the site.
Wall panels have cylindrical hollow cores incorporated with 8 No. 44 mm dia voids in the 75mm thick, 6 No. 62 mm dia. voids for the 92 mm thick and 6 No. 74 mm dia. voids for the 120 mm thick panels. Hollow cores are incorporated into the walls to reduce dead weight and facilitate mechanical, electrical, and plumbing services through hollows, thereby increasing sound and thermally insulating properties. The sides of all panels are tongued and grooved to facilitate positive jointing. These wall panels do not require stone or wood sills/frames to level surfaces for windows and openings. Lintels need not be cast as panels may be placed horizontally as lintels wherever required. Washbasins, cupboards, mirrors, paintings, etc. may be hung with regular plug screws.
Are robomatic panels related to civil engineering?
Yes, Robomatic Hollowcore Concrete Wall Panels are used in Civil Engineering
Use of the Robomatic wall panels & Limitations
Uses - These wall panels shall be used as non-load bearing walls/partition walls and compound/boundary walls in residential/ commercial/ industrial/ institutional buildings.
Scope of Assessment – Suitability of Robomatic wall panels for use as non-load bearing walls, compound/boundary walls in residential and commercial buildings etc.
Basis of Assessment
The assessment is based on the results & reports of
(i) Inspection of the manufacturing plant and equipment used
(ii) Assessment of quality assurance procedures implemented for the Quality Assurance Scheme followed by the Certificate holder for process control as per the Quality Assurance Plan attached to Annex I.
(iii) Reports of tests got done on 75mm, 92mm & 120mm thick wall panels from Bureau Veritas, Hyderabad by the manufacturer.
(iv) Tests got done on the samples of 75mm, 92mm & 120mm thick wall panels collected by the IO during inspection of the plant from Bureau Veritas, Hyderabad.
Scope of Inspection – The scope of inspection included the verification of production, performance and testing facilities at the factory including the competence of technical personnel and status of quality assurance in the factory
Manufacturing Machinery & Equipment
The firm has got fully mechanized Acotec Production Line of Elematic to make and Concrete Batching Plant of Schwing Stetter make, Truck mounted crane of Bharat Benz & Plafinger make, Forklifts of Godrej make, JCB Loader and Weigh Bridge. The components of these machines are given below:
I. Acotec Line
1. Concrete Feeder
2. Extruding, Cutting, and Plate feeding – Plate feeder, Plate feeder conveyor, extruder, cutter & electrification
3. Trimmer
4. Tipper and Recycling – Belt conveyor and Tipper
5. Stacking -- Pallet conveyor, stacker & stack conveyor
6. Restacking -- Stack conveyor, Crossing station, Re-stacker, Roller conveyor, Transfer tables, and Turning device
7. Cleaning and oiling – Plate conveyor and Cleaning and oiling
8. Delivery – Receiving conveyor and Chain conveyor
II. Batching Plant
1. Wet Mix Plant – capacity 30 m3/hr with 4 nos. in line bins of 16 m3 aggregate storage capacity
2. Planetary Mixer with a compacted output of 0.5 m3/ batch
3. Aggregates weighing system – with load cells suspended at 4 points of the conveyor belt
4. Pneumatically operated batching gates – 4 nos. for aggregates
5. Electrically operated Vibrator for sand/powder bin and cement/filler weigh
6. Chevron Transfer conveyor with carrier rollers
7. Cement/filler weighing system
8. Water weighing and Pump pressure-discharge system by
flow meter, water sprinkler pipeline
9. Planetary Mixer with a moisture sensor
Manufacturing Process
The manufacturing process of Robomatic wall panels is as follows:
Raw Material
Sieved manufactured Sand and 2-6mm stone aggregate shall be supplied to the plant where it shall be weighed and sieve analysis was done & silt content checked as per the quality assurance norms. Cement shall be supplied in closed bulkers directly from the manufacturers’ plant and fed into the cement silo directly using the blower.
Concrete Mixing
The concrete required shall be batched and mixed at an automatic batching and mixing plant with Planetary Pan Mixer and Moisture probes. The relatively dry aggregates shall be automatically weighed & batched into the mixer from Aggregate Bins. Two of the Aggregate bins shall be equipped with moisture probes to ascertain accurate weighing and water content calculation later in the final concrete mix. Afterward, cement and water shall be added to the mixture.
A low water-cement ratio of about 0.3 ensures that concrete is zero-slump and gains about 70% of its design strength within 12-24 hours of casting. The moisture content of the mixed concrete shall also be automatically controlled and adjusted by the software thus ensuring a consistent concrete mix at all times. The software auto-adjusts for water content based on readings of the moisture probes. After mixing, the concrete batch shall be fed to the conveying system, which brings fresh concrete to the hopper of the Robomatic Wall – a line where wall panels shall be cast, cut, trimmed, stacked, pre-cured, restacked, and strapped into bundles.
Extrusion Robomatic
Wall elements shall be formed in a continuously operating extruder. The concrete shall be compacted onto thin base molds, which support the products during the pre-curing time. Base molds shall be automatically fed to the extruder as a continuous ribbon. The base mold length shall determine the standard length of the products. There can simultaneously be a maximum of five plate lengths in the system. The extruder shall compact the concrete with extrusion screws against the packing bar and side walls. The top surface of the product shall be vibrated by a vibrating plate.
Cutting
After extruding, the products shall be cut according to the base mold length. A circular saw shall cut the fresh concrete on each base mold seam. Then the cut product together with the supporting plate shall be pulled to the stacker.
Trimming
When necessary, the fresh product shall be stopped at a specified point, where the manually adjusted circular saw cuts off the wanted trimming piece. Trimming length shall be max. 20 cm. The trimmed off concrete shall be recycled back to the extruder.
Stacking
Cut, fresh products shall be stacked into pre-curing stacks. Depending on the product thickness and weight each stack shall contain 4 to 10 products and base molds. Stacks shall be supported by steel pallets, which are automatically fed underneath each stack.
Pre-curing
The stacks shall stay 12 to 24 hours in the pre-curing indoor storage area where natural pre-curing occurs for each stack which is covered with tarpaulin to stop any evaporation and moisture loss. The storage shall be an area where natural curing occurs. Product stacks shall be moved into and out of the stock area by a forklift.
Restacking
After pre-curing the products are strong enough to stand automatic handling. Products shall be separated from the base molds. Base molds shall be returned back to circulation through a cleaning and oiling unit. The products shall be restacked to form delivery stacks with 4 - 10 products on top of each other. The stack shall be pushed against a wooden delivery pallet and turned on its side. Delivery stacks shall be strapped before transportation to delivery storage. Stacks must stay in the delivery storage where they shall be kept moist by external manual water sprinkling for at least 7 days before transporting to a construction site after 15 days on a Truck or Flat-bed Trailer. Loading of trucks shall be done with Forklift or Hydraulic Cranes.
Reusability of concrete materials
During manufacturing of Robomatic Hollowcore Wall panels, there is the possibility of wastage with concrete due to machinery tune-up at the beginning of every shift. But this should be taken as waste because, the concrete which could 9 not be manufactured into wall panels is looped to a separate line, dismantled into concrete again, and sent back to the machine for the casting of wall panels.
Due to this, there is zero percentage wastage in the plant. The plant operational personnel are trained well to handle these situations and whatsoever the reason for not casting at any instance will be reused.
The other possibility of wastage is during installation. In general, 3% of the total area of installation is allowed as wastage due to cuttings and leftover small panels due to the staggering installation of walls.
Even this 3% of wall panels are transported back to the plant and is used as coarse aggregate. The well-cured and formed panels left over at the site will be pulverized manually and mixed with the coarse aggregate in batches.
While the handling panels inside the plant area there is a small percentage of breakage of panels is observed. During quality checks, these panels are identified and sent to the raw material dump yard and pulverized manually, and mixed with the coarse aggregate of 2 – 8mm. The manufacturing Process flow chart is given in Annex II.
Durability
The durability of the wall panels is defined as the capability to resist weathering action, chemical attack, and abrasion while maintaining its desired engineering properties. It normally refers to the duration or life span of trouble-free performance. The panels are manufactured using M25 mix with a design mix of coarse aggregates 3-5mm, manufactured sand 0-2mm, cement, and an optimum mix of water as per IS 10262:2009 & IS 456: 2000.
As per the design of M25, it can withstand physical factors in general just like the regular concrete members, and physical forces like percolation and permeability of water through its medium and temperature stresses. In the same way, M25 design mix concrete can withstand chemical attacks viz., sulfate, and chloride attacks.
Installation Procedure
- Only two stacks shall be put on top of each other during stocking and transportation.
- Panel stacks shall always be lifted from under a wooden pallet with a lifting fork or belt.
- The panel stacks shall be moved by forklift or trolley to the construction site. The individual panel may easily be moved by a simple wheel. Panels can also be moved manually by inserting a short tube (500mm) into the second hollow as a handle. These shall always be transported sideways.
- Gluing agents (cement-based adhesives) as per IS 9103:1999 shall be mixed as per the manufacturer’s instructions.
- The line of the wall shall be marked on the floor and ceiling before the start of installation.
- Guiding boards shall be fixed on the floor and ceiling. The guiding support will automatically align the wall when lifting the panels straight into an upright position.
- The gluing agent shall be spread on the side of the already installed panel.
- Before the panel shall be lifted to an upright position, it should be moved so that the panel bottom is as close as possible to its correct position. After that, the panel shall be lifted to an upright position.
- This panel shall be pushed against the previous panel (and move up and down) so that tongue and groove are carefully positioned against each other and gluing agent is squeezed out. The correct thickness of the joint between two panels shall be 1 to 2 mm.
- The panel shall be positioned to the correct level by using wooden wedges at the bottom and top of the panel erected earlier. The height of the panel should be about 10 to 50 mm shorter than the free-room height.
- The top joint shall be filled with polyurethane foam. The correct thickness of the joint shall be 5 to 10 mm.
- Alternatively, when the same gluing agent as in the sides is used for the top joint, the panel shall be pushed against the ceiling so that gluing agent is squeezed out. The correct thickness of the joint shall be 1 to 2 mm. The surplus gluing agent shall be removed from joints after installation.
- The bottom joint of the panel shall be filled with mortar or concrete. The correct thickness of the joint shall be 10 to 40 mm.
- ‘Shoulders’ shall be sawed or flat steel bar for door top portion fixed to the panels next to the door. The door top piece shall be glued by using polyurethane foam or gluing agents. The joints should be as thin as possible.
- All corners shall be strengthened with nail plugs (3 per corner).
- Paper or fiber tape shall be glued to the corner joints and to the joints at a door top portion before plastering.
- Flexible joints between panels shall be built after each 5 – 6m. Polyurethane foam or mineral wool may be used as elastic joint material.
- The hollow boxes may be used for the cables and electrical boxes shall be fixed at the desired points after drilling.
- The panels need only a very thin skin coating (1-2 mm) before surface finishing. It may be easier to do with a wide trowel.
- All kinds of drilling and sawing can be easily made in the panels.
- The necessary tools required for installation shall be a hammer, saw screwdriver, level, meter rule, trowel, drill, trolley concrete cutter, steel bar, buckets, and lifting bars.
BMBA Board of Agreement of BMTPC
BMTPC Building Materials and Technology Promotion Council
CPWD Central Public Works Department
ED Executive Director of BMTPC
IO Inspecting Officer
MS Member Secretary of BBA
PAC Performance Appraisal Certificate
PACH PAC Holder
PACS Performance Appraisal Certification Scheme
SQA Scheme of Quality Assurance
TAC Technical Assessment Committee (of BMBA)