Pervious Parking Lot Project
Another job well done using FORTA® fiber in pervious concrete:
The project involved covering over 100,000 sq ft of paving and requiring over 9,000 lbs of the 2 ¼” FERRO-GREEN® pervious macro fiber. There were many interesting facets to the project aside from the use of fiber – a specially-altered laser-guided screed to accommodate the lay down of pervious concrete, the use of a SAP – Super Absorbent Polymer – additive, a hydration stabilizer admixture, a pizza-pan surface finish, and the use of a surface-sprayed cure-and-seal to eliminate the need for plastic cure covering.
Project owner LDS Church has specified and used macro synthetic fiber reinforcement as an alternate temperature/shrinkage reinforcement in meeting house slabs and temple floors for many years. Based on that experience, LDS also desired to add toughness and durability to a new pervious concrete parking lot project at their facility on the Arizona State University PolyTechnic campus in Mesa, AZ. The project involved over 100,000 square feet of parking spaces and driving lanes, placed over 10 inches of 1 inch-gravel water-retention and recharge bed material. In all, over 1,850 cubic yards of pervious concrete were placed at 6 inches thick for the parking areas and 8 inches thick for driving lanes, and included 5 lbs./cubic yard of the FORTA® FERRO-GREEN® macro fiber reinforcement. The pervious mix contained less than 500 lbs. of total cementitious, along with HydroMax® internal curing agent and a hydration stabilizing admixture. The design void content goal was 18% to achieve sufficient pavement infiltration. Pervious concrete supplier Arizona Materials delivered mixes that were extremely consistent, with a unit weight variance of less than 1 pound per cubic foot over the course of the project. The fiber-reinforced concrete was transported on-site by a conveyor supplied by Western Concrete Pumping, and struck off using a laser-guided screed modified by Barco Inc. After screeding, the surface was cross-rolled and final-finished using a Tornado Pizza Pan™ gas-powered trowel machine manufactured by Lura Enterprises, and then spray-cured with PerviouShield™ surface treatment to eliminate the need for plastic covering. Control joints were installed by sawcutting approximately 1 in. depth at a pavement age of 4 – 7 days. The FERRO-GREEN® macro fiber dosage was specified based on considerable research performed at the University of Missouri at Kansas City, where 5.0 lbs/cu yd proved optimum in a wide variety of durability performance areas. Pervious consultant Bob Banka of Concrete Management Systems was engaged to meet the specified requirement for an on-site NRMCA Certified Pervious Craftsman, and was able to guide project participants in all related aspects, including mix design, transport, placement and finishing. The added toughness courtesy of the 2 ¼” long FERRO-GREEN® macro fiber will help provide the owner with a durable and long-lasting pervious parking area that will be a point-to project for owners and specifiers that require adequate storm-water site management on a large-scale basis.
Project: LDS Church Pervious Parking Lot
Owner: Church of Latter Day Saints
Location: Arizona State University PolyTechnic Campus, Mesa, AZ
Pervious Concrete Contractor: Bowman Concrete Inc., Queen Creek, AZ www.bowmanconcreteinc.com
Pervious Concrete Consultant: Concrete Management Systems, Medina, OH www.concretemanagementsolutions.com
Ready-Mix Supplier: Arizona Materials, Phoenix, AZ www.arizonamaterials.net
Fiber: FERRO-GREEN® macro synthetic, 2 ¼” length, 5.0 lbs/cu yd