Equipment World

September 2016

Equipment World Digital Magazine

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CONCRETE CONTROL EquipmentWorld.com | September 2016 57 C oncrete mixtures for paving present unique challenges, primarily because most pavement designs require the mix to stand up, particularly at the edges and back of the paver. Thus, it's critical for the mix to have the correct proportions of the three main components: ce- ment, water and aggregate. The aggregate is the biggest part of a concrete mixture's volume and weight. It's also the cheapest portion of the mixture, and the least uniform component. While cement and water are critical and need to be moni- tored, the aggregate poses the road science | by Chris Hill | ChrisHill@randallreilly.com Uniformity makes or breaks quality concrete pavement mixes, and it all begins with managing the aggregate. Concrete plant checklist Source: Integrated Materials and Construction Practices for Concrete Pavement, Federal Highway Administration Publication No. HIF-07-004 • Check foundations of stockpiles for proper separation and adequate drainage. • Check bins for adequate partitions to prevent intermingling of aggregates. • Check scales with test weights throughout range to be used. • Check scales for seals by approved agency. • Check water meter for accuracy. • Check for leakage of lines. • Check capacity of boilers and chillers if their use is anticipated. • Check admixture dispensers for accuracy. • Check mixers for hardened concrete around blades. • Inspect concrete hauling units for cleanliness. • Check to ensure that all concrete- making materials have been certifi ed and approved for use. • Observe stockpiling operations. Verify that segregation and contamination will not occur. • Observe the charging of the bins. Verify that segregation and contami- nation will not occur. • Review aggregate moisture tests. • Observe batching operations at start and periodically during production. • Check scales for zeroing. • Check to ensure proper batch weights are set on the scales. Arizona DOT A portable Portland cement concrete batch plant positioned alongside Arizona Loop 303 northwest of Phoenix.

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