Recently NRMCA’s Engineering Division performed a survey where it asked the Research and Engineering Standards (RES) committee members for their five most onerous prescriptive requirements. RES members selected the following requirements (in this order):
a. Maximum w/cm when not applicable
b. Minimum cementitious content
c. Restriction on SCM dosage
d. Restrictions on aggregate characteristics like grading
e. Restriction on type and characteristics of SCM (Class F fly ash only etc.)
Next, RES Committee members were asked to provide for section construction project specifications (section 03300); 102 concrete specifications were obtained. NRMCA engineers looked at each specification and noted if each of the specifications had any of the above five prescriptive requirements. If a specification had all five requirements then it was calculated as 100% prescriptive. Over the 102 specifications the calculated average was 51% prescriptive. This means that on average each specification has 2-3 prescriptive requirements out of the five that were considered. The percent of specification having each prescriptive requirement was calculated as follows:
a. Restriction on SCM dosage – 85%
b. Maximum w/cm when not applicable – 73%
c. Minimum cementitious content – 46%
d. Restriction on type and characteristics of SCM (Class F fly ash only etc.) – 27%
e. Restrictions on aggregate characteristics like grading – 25%
A full report is being developed and will be published shortly as an article. NRMCA plans to conduct this survey every three years to track the industry's progress toward performance based specifications.
For more information, contact Karthik Obla at email@example.com.