Page 6 - Open-Access-February-2020

TECHNICAL PAPER

Biofuel
Cement
wind 0.19%
Production Gas Oil 4.4% solar
9.6% 0.012%
Coal
Concrete 0.065%
water
Plant service Life end of Life
treatment
Operations Nuclear
Hydro 62%
24%
Aggregate LEGEND: Transportation of
Production Materials (Road, Boat)

Figure 1: System boundary for LCA of general use cement concrete
products. Figure 2: Ontario’s electricity supply mix for 2014 [15] .

Cement production is the extraction and transportation of raw Equation 1
materials, the manufacturing of cement including blending, strength (MPa) alt. material j RCPT (C) base material
grinding, and pyroprocessing, and cement transportation. FU j = strength (MPa) base material * RCPT(C) alt.material j
Aggregate production includes the extraction, processing,
and transport of fine and coarse aggregates. Concrete plant where j corresponds to each alternative mix design, as described in
Table 1
operations include batching and mixing activities, and transport
of concrete to the site where it will be placed. End-of-life is 3. LCA – LIFe CyCLe INveNtORy
the in-place rubblizing of concrete. This system boundary is
modified to model the alternative concrete constituents as The Life Cycle Inventory (LCI) for concrete, representing the
described in Section 3. inputs and outputs throughout the product’s life cycle, was
compiled based on a baseline LCI for conventional concrete
2.2.3 Functional Unit containing GU cement and virgin aggregate (represented in this
paper by the mix 100GU). This base model was then adjusted to
The purpose of the functional unit is to provide a basis for model each alternative constituent, namely SL, FA, SF, and GUL.
the quantification of all inputs and outputs (i.e. a reference
point for which data is collected), and to allow for comparison
of LCA results based on equivalent functional performance 3.1 Processes Included in the Life Cycle of
of different materials, processes or products. Concrete Conventional Concrete
used for infrastructure is commonly specified according
to its 28-day compressive strength (MPa) and 28-day rapid 3.1.1 Cement Production Process
[4]
chloride permeability (RCP) (Coulombs (C) using the ASTM A report released by the Athena Sustainable Materials Institute
C1202 [13] ) requirements. These two properties are included contains detailed LCI data for the production of cement. The
in the functional unit, which has been studied in detail by raw material, energy use, atmospheric emissions, liquid effluent,
the authors [14] . Table 2 presents the experimental results for and water usage data presented in the Athena report was used
compressive strength and RCPT corresponding to the mix to create the Cement Production process in all of the LCA
designs shown in Table 1. Equation 1 describes the calculation models. The data for the Central Region of Canada (Manitoba
of the functional unit. and Ontario) was used for this research.

table 2: Hardened properties
MIX DESIGN ID
hARDENED pROpERTY 100Gu* Gu-25Sl Gul-25Sl Gu-8SF-25Sl Gu-10FA Gul-10FA

28 day f’c (MPa) 48.5 36.0 34.7 56.5 51.2 50.6
28 day RCPT (C) 3186 2135 1969 421 3614 4024

* Base case scenario

The IndIan ConCreTe Journal | FeBruarY 2020 11