GNBS implements national standard for ready-mixed concrete

The Guyana National Bearu of Standards (GNBS) has developed the National Standard “GYS 227 – Specification for Ready-Mixed Concrete.” The implementation of this new standard is a result of the growing construction sector in the country, it was noted that several local companies are producing ready-mixed concrete to meet the demands of the rapidly growing construction sector.
As such the GNBS has established a criterion for the production of ready-mixed concrete in Guyana. This standard defines ready-mixed concrete as concrete delivered to the site or into the purchaser’s vehicle in a plastic condition, ready for placement without further treatment.
The standard specifies the conditions for production and delivery of ready-mixed concrete, including methods for nominal mixes, specified strength mixes, and specialised mixes. It also outlines how purchasers can specify the required properties of the concrete in their orders. Additionally, the document provides guidance on the information that purchasers should provide when ordering ready-mixed concrete, the inspection facilities required from the supplier, and the necessary tests. It distinguishes routine tests conducted by the supplier from those the purchaser is responsible for.
However, the GNBS stated that standard does not cover the placement, compaction, curing, or protection of concrete after delivery, nor does it apply to materials for lean concrete or similar road base materials. Regarding materials used in ready-mix, the standard specifies that water should be clean and free from impurities that could affect the concrete mix adversely. Cement should be measured by weight or in whole bags as delivered by the manufacturer, while aggregate should be measured by weight.
Two types of mixers are specified: stationary mixers and truck mixers (or truck agitators). If a stationary mixer is used, the mixing time should be at least two (2) minutes, unless otherwise specified by the manufacturer. For truck mixers, a revolution counter must be provided, and mixing should continue for at least 100 revolutions at a rate of not less than seven revolutions per minute, as per manufacturer specification.
The standard also sets requirements for concrete delivery, focusing on discharge time and the information that must be included on the delivery ticket. It stipulates that the basis of supply should be in cubic meters, as agreed between the purchaser and the supplier.
The standard covers inspection, sampling, and testing of ready-mixed concrete to ensure confidence in the quality of the product supplied. The GNBS encourages suppliers of ready-mixed concrete to be guided by the requirements of this standard to ensure the consistent delivery of a quality product to consumers.