Liv Haselbach

A New Test Method for Porosity Measurements of Portland Cement Pervious Concrete

Pervious concrete is emerging as an alternative material for paving to help curtail nonpoint source pollution problems. The porosity of pervious concrete is an important variable needed for pavement system design and for material comparisons. This paper researches a method for measuring the porosity of pervious concrete from field-obtained cores by applying the Archimedes principle and using standard materials laboratory equipment. The error between different operators at different testing facilities was found to be around 2.2 % porosity.

Vertical Porosity Distributions in Pervious Concrete Pavement

Pervious concrete is an alternative paving material that may alleviate many of the environmental problems caused by urban runoff from developed areas. Additional research is important so that pervious concrete can be better specified and more effectively used. An important property of pervious concrete is porosity, which will affect the hydrological and strength properties of the material. This research shows that there is a vertical distribution of porosity in slabs placed with certain placement techniques. The vertical variation of porosity can affect the strength distributions within the material and the permeability of the system and its potential for clogging. These studies indicate that for slabs approximately 15 cm (6 in.) in height and placed with an approximately 10% surface compaction technique, the porosity increases significantly from top to bottom. A series of vertical porosity distribution equations have been developed to effectively model this using the percent compaction and average cored porosities.

Cyclic Heat Island Impacts on Traditional Versus Pervious Concrete Pavement Systems

As the world becomes more urbanized, concerns over the urban heat island (UHI) are more pronounced. Increased urban temperatures have a negative affect on the natural and human environment by producing increased energy usage and smog formation. Pervious concrete pavement is one technology that may help mitigate increased urban temperatures. Temperature data from an instrumented site in Iowa and heat storage phenomena for various weather patterns are presented. The site contains both pervious concrete pavement with a solar reflectance index (SRI) of 14 and traditional concrete pavement with an SRI of 37. Leadership in Energy and Environmental Design (LEED) accepted a high SRI (>29) as one method to characterize a cool surface. Heat capacities of both systems were studied along with a sensitivity analysis of the inputs. The research supports the conclusion that even though pervious concrete may have a much lower SRI than traditional concrete made with similar materials, it can be considered a cool pavement option. In addition, daytime rainfalls combined with the internal high surface area result in significantly more removal of stored heat from the system, with a more rapid mitigation of UHI impacts and reduction in the potential for thermal shock from impervious surface runoff.

Effectively Estimating In situ Porosity of Pervious Concrete from Cores

Pervious concrete is an alternative pavement material which may help reduce nonpoint source pollution problems. The porosity of pervious concrete is an important parameter used for both pavement and environmental design and is dependent on field placement techniques. It is recommended that porosity be tested on field-placed specimens. It has been noted that some of the concrete is knocked out while coring from field-placed samples which may affect the porosity. This paper researches a methodology for estimating the in situ porosity of pervious concrete from the porosities of cores taken from the field based on aggregate size, core size and porosity.

Coupled oil analysis trending and life-cycle cost analysis for vessel oil-change interval decisions

ABSTRACT Extending lube oil-drain intervals is a practical way to save money on engine operating costs. At the same time, there may be increased risk of engine damage with increased drain intervals. The risks and benefits can be difficult to weigh and, as a result, starting an oil-drain interval extension programme can be an intimidating endeavour. This paper combines oil-analysis programme data interpretation and life-cycle cost analysis (LCCA) into a methodology for weighing oil-drain interval options. LCCA has shown decreasing incremental cost savings as oil-drain intervals are further extended, indicating that highly extended drain intervals may not be necessary to reap the majority of available cost benefits. Using oil-analysis property trending with life-cycle cost savings can allow an engine operator to set an hours-based extended drain interval based on projected risks and benefits. This interval is set as the baseline under the protocol, but continual oil analysis is used as a precaution to protect against unpredictable events. This methodology helps to reduce the risk of engine damage and ensure that the most easily attainable cost savings are still captured, making the decision about how to extend oil-drain intervals more approachable.

Estimating the Modulus of Elasticity of Pervious Concrete Based on Porosity

The modulus of elasticity is an important property for evaluating the mechanistic response of any material under load, and porosity influences the rheological, mechanical, and hydraulic properties of pervious concrete. The relationship between porosity and modulus of elasticity of pervious concrete has not been well researched. In this study, pervious concrete cylinder specimens were prepared for a range of porosities and compression tests were performed to determine the moduli of elasticity. Secant moduli of elasticity at five different stress levels (i.e., 2.2, 2.8, 3.3, 3.9, and 4.4 MPa) were calculated from the load-deformation data of the compression tests. Three performance zones were proposed for estimating the modulus of elasticity based on porosity at the stress levels of 2.2 and 2.8 MPa, i.e., lower, average, and upper. These performance zones provide designers with more information based on the variability and heterogeneous distribution of porosity in a pervious concrete section for risk-based assessments. While more research is required for comprehensive characterization of pervious concrete, the modulus of elasticity equation in the lower performance zone might provide an initial performance assessment of pervious concrete until its components can be better characterized.

Modified Media Filter Drain Mix with Alternate Aggregate Grading

The media filter drain (MFD) or Ecology Embankment is a best management practice (BMP) approved to treat copper and zinc in highway runoff in many states. High levels of these metals may impact coldwater aquatic species in receiving waters. The MFD was originally based on a gradation of aggregate no longer readily available in Washington State and this research investigated substituting the original aggregate specification with a more widely available AASHTO Grading No. 8, which has slightly fewer fines. Results indicate that the MFD is effective at removing dissolved copper and zinc using the alternate aggregate specification in the MFD mix. Column experiments were used to show that the alternate MFD mix had a higher median removal rate than a suite of typical stormwater control BMPs for both dissolved zinc and copper, qualifying it as an enhanced treatment method. In addition, it was shown that the MFD mix design can be loaded with dissolved metals for at least 14 years with no loss in performance, even when subjected to larger storms. MFDs built with a wider range of aggregate gradations may be more economical in other regions based on standard aggregate gradations available.

Carbon Sequestration in Old and New Portland Cement Concrete Pavement Interiors

Measurements of carbon emissions and sequestration are important in estimating the global warming potential of the built environment. Manufacturing of portland cement contributes to a portion of anthropogenic CO2 emissions through the chemical process of calcination. CO2 can also be sequestered from the air into concrete in the reverse process commonly called carbonation. Most research studies on carbonation typically focus on the exposed surfaces where the levels might be high. There is little information on the CO2 which might be sequestered in the interior of pavements. Together, the near surface measurements and the interior levels will provide better information on carbon sequestration. Pavement samples that were from one to 85 years old were sliced and paste/mortar specimens were chipped from different depths. CO2 sequestration was estimated using a thermo-gravimetric analysis (TGA) for the carbonate levels and X-ray fluorescence analysis (XRF) for elemental analysis. The results indicate that the amount of carbon sequestration in the interior of these pavements is in the early years of life around 10% of that released during calcinations increasing to 25% or more in arid climates. Interior carbon sequestration in humid climates might exceed 35% or more over several decades, but more information is needed to validate this.

GREEN RATING INTEGRATION PLATFORM – A DECISION MAKING TOOL FOR MULTI-MODAL FACILITIES: CREDIT HARMONIZATION AND A SUSTAINABLE WATER & MATERIAL PRACTICES CASE STUDY

ABSTRACT There are multitudes of sustainability rating systems and guidelines, and it is difficult to decide which ones to use and how to use them. In addition, multi-modal projects have different ...

A Method to Estimate Carbon Dioxide Sequestration in Concrete Pavement Interiors

Ordinary Portland cement (OPC) is used in many pavements which reabsorb some of the CO2 emissions from the initial cement production over time in a process commonly referred to as carbonation. Estimating the extent of CO2 sequestration throughout pavements is crucial in understanding their true carbon footprints. Surface carbonation has been classically modeled with a front of extensive carbonation that slowly moves inward with rates on the order of millimeters per year, but provides little sequestration information beyond the front, which was usually assumed to be negligible. This work proposes an isopleth (chart with lines of similar characteristics) method for estimating average CO2 sequestration deeper within pavement samples based on quasi-steady-state equilibrium partitioning at various ages using material and chemical characteristics. Together with the surface carbonation model, the isopleths might provide more comprehensive carbon dioxide sequestration estimates. One inch (25.4 mm) deep hydrated cement samples were prepared, aged for several years with only their top surfaces exposed, and then analyzed for CO2 sequestration along their depths with thermal gravimetric analyses. The results indicate average interior CO2 sequestration levels exceeding 25 % based on moles of calcium in periods under three years, and even higher levels when samples are made with 25 % low calcium supplementary cementitious material. Similar tests on aged concrete samples would be needed to extrapolate the method to pavements.