Effects of Pumice as a Partial Replacement on the Performance of Pervious Cement Concrete
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Date
2019-12-02
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Addis Ababa University
Abstract
Pervious cement concrete pavement is an innovative pavement system, which have the ability to
drain water and absorb traffic noise generated by tyre-pavement interaction. Its use in parking
lots, walkways and low traffic zone pavements has been promising in the past. The main feature
that differentiates pervious cement concrete from any other mixes is, its large interconnected
pores measuring up to 35% of the total volume of concrete. Despite the effectiveness of these
large interconnected pores to drain water and absorb noise, their negative effect on strength is
significant. Therefore strength and permeability are of special properties that need to be
balanced.
Whether conventional dense graded concrete or pervious concrete, the structure of the aggregate
to cement matrix remains the same i.e. aggregate, hardened cement paste (hcp) and interfacial
transition zone (ITZ) are the main components. ITZ is the weakest in the solid system of
pervious concrete and is a region where crack initiation and propagation occur with less energy.
Therefore, a mechanism to increase the strength of ITZ i.e. which can be taken as the whole
concrete system shall be devised.
Little research has been conducted that characterizes the performance of grounded pumice (GP)
on pervious concrete. In this research, the performance of GP as OPC replacement is
investigated. The characterizations are done using compressive, splitting tensile strength,
permeability, hardened density and porosity tests. The experiment is designed by preparing
control mix containing 100% OPC and the experimental mix that contains 5%, 10%, 15%, 20%,
25% and 30% GP. Tests are conducted at the ages of 3,7,28 and 56 days.
Based on the experimental investigations, GP has resulted an increase in compressive and
splitting tensile strength up to 11% and 26%, respectively. It is also found that, GP can partially
replace OPC up to 15%. The optimum replacement level both for strength and permeability is
found to be 5%. The ideal porosity that reconciles hydraulic conductivity and strength is found to
be 17%. The high water demand by addition of GP has also been mitigated by proposing
consistency driven water demand for pervious concrete mixes containing GP.
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Keywords
Consistency Driven Water Demand, Grounded Pumice, hcp, Hydraulic Conductivity, ITZ, Pavement, Pervious Concrete, Pozzolanic Materials