381
4000.041
Committee of Southern California Ready Mixed Concrete Association. Chairman: Jumper, Everett
Paper
Southern California Ready Mixed Concrete Association
1963
1-16
N
Early in February 1963 a special meeting was held at the Southern California Ready Mixed Concrete Association headquarters with their Technical Committee, representatives of the Lightweight Aggregate Producers, and engineers from the building code enforcement agencies of the City and County of Los Angeles, the State of California, and the International Conference of Building Officials.The purpose of this meeting was to discuss methods of improving the control and production of lightweight concrete. Certain problems had developed in the industry on a few specific jobs and it was felt advisable to develop corrective measures to improve the quality to satisfy all basic code requirements. The properties of lightweight aggregate which must receive proper consideration include (a) gradation, (b) weight per cu ft, (3) specific gravity, (d) absorption, and (e) yield.
Since strength of concrete is one of the primary code requirements, it was suggested by the code enforcing agencies that two basic recommendations might be made to improve this property. First, it was felt that aggregate gradation was significant and that coarse aggregates might be furnished in two separate sizes and batched individually at the ready mix plant. Secondly, to insure adequate strength on the job, it was suggested that laboratory design mixes be required to have strengths greater than specified in the present code.