Quality Control Procedures Required for Plant Certification
Updated 04/14/2021

CSI plant certification shall not be construed as conferring or creating any claim, right, or remedy in customers/clients of the CSI member/producer, the general public, or any other third party nor creating any duty by CSI or the member/producer to customers/clients of the member/producer, the general public, or any other party.

The CSI plant certification program is not intended to and does not certify or warrant products of a CSI member/producer in any manner whatsoever.

The Cast Stone Institute has a commitment to establish a standard of quality that will be recognized and respected by the general public. Cast Stone Institute producer members must be able to attain that standard on a consistent basis.

The plant inspector should determine each of the following items. Each section will be graded according to percentage of compliance. All mandatory items must be in place and the average percentage of compliance for all sections must exceed 80% to qualify for producer membership. Continuing members should exceed 90% compliance with these items, plus 100% of the mandatory items.

Company Name:

Inspection Date:

Name of Inspector:

M - Mandatory 100%
P - Primary 90%

Successful CSI Plant Certification will take place only if the plant obtains the following:

1. 100% of all the Mandatory items.
2. 90% of the Primary items.

The following are identified and maintained:


Yes No
A. Sales/Estimating

B. Drafting

C. Production

D. Quality Control

E. Testing Technician M
  - Current Certificate of Completion   M
F. Delivery and Project Coordination


Current Member Criteria:

Each Producer Member must submit testing records to the Institute office between March 1st and March 15th, and also between September 1st and September 15th of each year in order to maintain plant certification.

This submission shall include:

1. The last 60 days of 500 CF test data for both compressive strength and absorption, tested in accordance with ASTM C1194-19 and ASTM C1195-19a.

2. A current (within the last six months) Independent Lab test, meeting the physical requirements set forth in ASTM C1364-19 for both compressive strength and absorption, tested in accordance with ASTM C1194-19 and ASTM C1195-19a.

If multiple deficiencies are found in the submitted data, the member will be placed on a quality audit list and required to submit monthly samples to the testing laboratory contracted with the Cast Stone Institute for a period of six months, and the results will be sent to the Institute office for review. The expense of this testing will be the responsibility of the Producer.

New Member Criteria:

In order to qualify Producer Membership, the following records must be submitted to the Institute office along with membership application.

1. Current Independent Lab test (within the last 6 months) indicating applicants ability to manufacture cast stone that meets the requirements set forth in ASTM C1364-19, when tested in accordance with ASTM C1194-19 and ASTM C1195-19a.

2. The last six months of 500 CF test data from in house or independent lab testing for both compressive strength and absorption requirements set forth in ASTM C1364-19 and tested in accordance with ASTM C1194-19 and ASTM C1195-19a in house or independent lab reports.

3. A current (within the last year) passing Freeze/Thaw test, tested in accordance with ASTM C666 as modified by ASTM C1364-19. Freeze/Thaw test to be performed by the lab contracted by the Cast Stone Institute.

Current Records:
(less than (1) one year old)

Yes No  
Approved Mix Design Requirements that meet or exceed ASTM C1364-19. M
Approved Shop Drawings. M
Mill/Test Reports-Reinforcing, Cement, Aggregates. M
Retain Monthly Sieve Reports for Last 24 Months. M
Scales are checked and calibrated annually by a state licensed scale company (see state certification papers). M
ASTM Certificates for All Materials:
A. Cement (Meets ASTM C150) M
B. Steel/Rebar/Other Applicable Reinforcing (Meets ASTM A615) M
C. Aggregates (Meets ASTM C33 except for gradation with monthly sieve analysis reports) M
D. Admixture (Meets ASTM C494, if mix design requires the use of a water reducing, retarding, or accelerating admixture). M
E. Color Pigments (Meets ASTM C979) M
  F. Water (Potable) P

Test Reports and Data Requirements:

Yes No  
Compressive Strength With minimum 6,500 psi by independent lab tests at least every 6 months for each production method, as per ASTM C1194-19. M
Water Absorption less than 6% absorption by independent lab tests at least every 6 months for each production method as per ASTM C1195-19a - cold water only. M
Freeze-Thaw Test Report indicating compliance with ASTM C666 as modified by ASTM C1364-19 within the last 24 months for each production method. M
Linear Shrinkage Test Report as per ASTM C426 as modified by ASTM C1364-19 within the last 24 months for each production method. Sample to be tested within 60 days of production. M
Current Industry Standards on file – ASTM C1364-19 (Standard Specification for Architectural Cast Stone), ASTM C1194-19 (Standard Test Method for Compressive Strength of Architectural Cast Stone) and ASTM C1195-19a (Standard Test Method for Absorption of Architectural Cast Stone). M
Current CSI Specification 04720 and Industry Standard TMS 404, 504, 604 (Standards for Design - Fabrication - Installation of Architectural Cast Stone). M
Product Data and SDS Sheets on hand for all admixtures, release agents and chemicals used. M
Product Delivery Records are maintained. P
Product Inspection Records are maintained. P

Quality Control Testing:

Yes No
As required by most current ASTM C1364-19, one sample from every 500 cubic feet cast will be tested to meet ASTM C1194-19 and C1195-19a in house or by independent lab and records kept for last 24 months on file. M
All new mix designs used in production of material, classified as cast stone, in accordance with ASTM C1364-19 and cast stone specification 04720, shall be tested for strength and absorption compliance prior to producing units. M

General Plant Safety Requirements:

Yes No
All CSI plants will be OSHA compliant per a letter of compliance from one of the following: M


OSHA consulting service      


Producer/Member's Insurance Company


Local Safety and Health Independent Consultant      
  Appropriate Cast Stone S.D.S. documents M

Shop Drawings:

Yes No  
All dimensions and details are shown on shop drawings. M
Units are identified with a piece Marking system. M
Finished surfaces are delineated by identifiable marks on all drawings. M
Handling/Lifting Devices, when shown (Type and Location). M


Yes No  
Samples are on file and in finishing area for all projects being manufactured. M
All samples clearly marked and readily identified. M
Samples are easily accessible and available for review of all products being manufactured, and mix designs on file. M

Raw Materials:

Yes No  
No Cross Contamination of Aggregates in bins consisting of walls and a floor. M
Bag cement is protected from elements. M
Bag cement is stored clear of the ground. M
Rotate stock of bagged cements so oldest bag is used first. P
Control Samples are kept of each raw material being used for comparison to new deliveries. M
Grade of reinforcing stamped and is verified at time of delivery. All reinforcing to be grade #40 or greater. M

Batching Procedures:

Yes No  
Approved Mix Designs are on file and posted or displayed at mixing station. M
Batching methods are by volume or weight capable of consistency of 3% ± M
Proper mixing procedures are followed, moist aggregates, cement, water and admixtures as recommended by manufacturer. P
Check water content in mix by moisture meter or other consistent procedure. A slump/flow spread test is used for verification of wet cast mix. M
Mixers are clean and have adequate lighting and are in good, safe repair. M
Mixers are completely discharged after mixing before a new batch is begun. M
Mix is transported to final mold by means that prevent contamination. M
Mixers are thoroughly cleaned between color changes, in order to prevent color inconsistencies. M


Yes No  
Molds must be constructed as not to deflect or move during casting. M
A qualified casting person checks all molds for correct dimensions prior to casting. M
Removable or Drafted sides are provided on all molds to prevent damage while de-molding. M

Vibrant - Dry Cast Stone:

Yes No  
Employees are using short stroke bench rammers of adequate size and pressure to tamp earth moist mix. M
All molds are checked dimensionally before filling with mix. M
Molds are secured in all areas to maintain dimensions. M
Tampers must be aware of mix moisture conditions at all times, useable working time 60 minutes, max. No dry or re-tempered mix shall be used. M
Tampers scratch between layers with a hand rake. M
Tampers place reinforcement after raking between layers. M
Tampers work in a straight back and forth overlapping pattern. M
Exposed sides of product appear as dense as the face of the piece. M
Bottoms of produced pieces are to be smooth even though they are not exposed. M
Finished edges are tooled, as needed, before sending stone into the curing area. M
Curing is done in a controlled environment for not less than 12 hours after casting. M

Wet Cast Stone:

Yes No
All molds are sealed and made watertight by either using silicone caulk or foam tape or other suitable sealing material. M
All surfaces of molds in contact with the stone mix must be coated with a mold release agent. P
Stone mix is to be evenly placed in the mold, internal vibrator not to be used to spread mix. M
Adequate vibration is to be used to consolidate mix in mold and to minimize air voids. M
Non-Exposed areas of produced pieces are to be finished with a float or trowel so as to have a flat finish. M
Steps are taken to contain and keep in moisture during the curing process. M

Machine Made Cast Stone:

Yes No
Molds and shoes are periodically checked for wear in order to maintain crisp edges. M
Exposed sides of finished product appear as dense as the face. M
Stone mix is to be evenly placed in the mold, internal vibrator not to be used to spread mix. M
Regular maintenance schedule is followed for all moving parts of automated equipment & repair. M
Mix design for machine-made material should be the same as that used for hand-made material. M
Curing is done in a controlled environment for not less than 12 hours after casting. M


Yes No
The product finish is to be a fine-grained, or custom texture per CSI standard color and finish specification. M
Finish area has adequate equipment and lighting for handling, finishing and palletizing finished stone. P
Trowel marks or imperfections on finished surfaces are sanded or washed away. M
Stones are identified by project number and adequately packaged to prevent damage in transit. M

Finished Product Requirements:

Yes No
All stones are checked dimensionally using approved shop tickets or drawings. M
All stones are checked against the sample for color and texture finish. M
Stone tolerances are checked according to CSI standards. M
Piece marks are both visible and permanently marked on each stone and the outside of each pallet. M
No seams, tamp marks, patches, imperfections or air voids are visible from a distance of five feet in direct sunlight on any exposed side of the stone. M
All stones are checked for soft edges, or soft tamping, ragged edges, visible cracks, or foreign matter in the face of the stones. M

General Plant Requirements:

Yes No  
Plant has sufficient heat to maintain a minimum 60 degrees. P
Plant has adequate lighting in all production and finish areas. P
Plant has sufficient storage room for at least one month’s production within the confines of plant premises. P
All stones are palletized or properly stored off the ground and are marked clearly for quick identification. M
Housekeeping is carried out throughout the plant and storage areas are kept in a neat and orderly manner free of all debris. M