Compaction Energy Research Articles

Design of the strong and durable of flexible pavement on road segment with the heavy traffic and overloads

The arterial road sections are generally heavy vehicles that tend to exceed the standard load so that the existing pavement surface is not able to survive according to the design life despite using modified asphalt. This has been proven by the occurrence of a heavy damage in a relatively short time on most primary arterial roads in Indonesia. In this paper, the method of implementation and criteria for the construction of pavement layers with a certain thickness has been prepared according to the planning standard for the volume of excessive vehicle loads and taking into account extreme weather conditions in Indonesia. There are three (3) main things in this paper that become an important factor in determining the structure of a solid and durable; they are the sand as layer controlling deflection (stabilizer), the weight of the Vibratory roller more than 25 tons to achieve maximum of compaction energy for base course, and a single-layer of AC-Base as a surface layer as anticipation of rutting and bleeding. Single overlays in each layer are rigidly constraining overall construction, while the sand layer can neutralize deflection due to overload and force due to the vertical force of subgrade, so that these three factors are energy deposits in the pavement construction that will work when an increase in load exceeds the standard.

Coupled three-dimensional discrete element–finite difference simulation of dynamic compaction

Discrete element method has been widely adopted to simulate processes that are challenging to continuum-based approaches. However, its computational efficiency can be greatly compromised when large number of particles are required to model regions of less interest to researchers. Due to this, the application of DEM to boundary value problems has been limited. This paper introduces a three-dimensional discrete element–finite difference coupling method, in which the discrete–continuum interactions are modeled in local coordinate systems where the force and displacement compatibilities between the coupled subdomains are considered. The method is validated using a model dynamic compaction test on sand. The comparison between the numerical and physical test results shows that the coupling method can effectively simulate the dynamic compaction process. The responses of the DEM model show that dynamic stress propagation (compaction mechanism) and tamper penetration (bearing capacity mechanism) play very different roles in soil deformations. Under impact loading, the soil undergoes a transient weakening process induced by dynamic stress propagation, which makes the soil easier to densify under bearing capacity mechanism. The distribution of tamping energy between the two mechanisms can influence the compaction efficiency, and allocating higher compaction energy to bearing capacity mechanism could improve the efficiency of dynamic compaction.

Effects of Freeze–thaw Cycles and Porosity/cement index on Durability, Strength and Capillary Rise of a Stabilized Silty Soil Under Optimal Compaction Conditions

Recent studies present the effects of freeze–thaw cycles (F–T) and porosity/cement ratio (η/Civ) on the strength and durability of chemically stabilized soils. However, the effects of η/Civ on strength and durability have not yet been studied for optimal conditions of compaction of silt-cement mixtures. Thus, this paper discusses the mechanical properties and durability of a chemically stabilized silt that undergoes freeze–thaw (F–T) cycles with rapid hardening Portland cement when molded in three compaction energies under optimal conditions (i.e. maximum dry density and optimum moisture content) using cement contents of 3–9% by weight. The results show a decrease in the split tensile and unconfined compressive strength of the mixtures when submitted to several F–T cycles, and an increase in the accumulated mass of loss (ALM) influenced directly by the η/Civ index. Freezing–thawing action may have weakened the effect of cement hydration products on filling in soil pores and bonding soil particles causing microcracks. The results also show that it is possible to establish a constant split tensile/compressive ratio of 0.16 regardless of the number of F–T cycles, the η/Civ index, and ALM. Nevertheless, the η/Civ index directly influenced the ALM, qu, qt, and also water absorbed by the capillary rise of all the samples. Finally, it was found mixtures that comply (in terms of durability at low temperatures and strength), requirements to be used in geotechnical constructions.

Effect of Reclaimed Asphalt Pavement Heating Temperature on the Compactability of Recycled Hot Mix Asphalt.

The compactability of an asphalt mixture is related to the heating temperature of the materials, but the heating temperature of reclaimed asphalt pavement (RAP) is limited by the production process of hot-in-plant recycled mixtures. To choose a reasonable heating temperature for RAP according to the compactability, the compaction energy ratio (CER) obtained from the Superpave gyratory compactor compaction curve was developed. The CERs of fourteen kinds of asphalt mixtures made with different RAPs were compared, all of which were different in type, content, and heating temperature. The results indicated that CER is an effective energy index to evaluate the workability of a bituminous mixture, and it considers both the accumulated energy after each gyration and the number of gyrations. It was also found that increasing the heating temperature of the RAP cannot always improve the workability of the recycled mixture, because the higher heating temperature caused more hard-aged bitumen to be blended with soft virgin bitumen during the mixing process. At the same RAP heating temperature, increasing the RAP content made it more difficult to compact the mixture, especially for RAPs with styrene–butadiene–styrene (SBS) modified bitumen, and the recycled mixtures with SBS-modified bitumen were more difficult to compact than those with nonmodified bitumen.

Evaluating the electrical resistivity of microbial-induced calcite precipitate-treated lateritic soil

Organisms or chemicals introduced into soils for soil improvement tend to make such soil reactive and this may affect the parameters that are used to determine the engineering and other properties of the soil. In this study, the electrical resistivity of Bacillus pumilus microbial-induced calcite precipitate-treated lateritic soil at different compactive effort was evaluated; lateritic soil was treated with stepped densities of B. pumilus suspensions of 0/ml, 1.5 × 108/ml, 6.0 × 108/ml, 12 × 108/ml, 18 × 108/ml and 24 × 108/ml, respectively, and compacted with three compaction energies, namely British Standard Light (BSL), West African Standard (WAS) and British Standard Heavy. The treated soil samples were cured for 7, 28 and 56 days to also see the effect of the curing period on the resistivity of the treated lateritic soil. The resistivity test result shows an increase in resistivity value with an increase in B. pumilus suspension density and also with an increase in compactive energy. Though there is a marginal increase between BSL and WAS compactive effort. The peak resistivity value was obtained at 2.4 × 109 cells/ml of B. pumilus suspension density for all compactive effort considered. The effect of curing days indicates that beyond 28 days there is only a marginal increase in resistivity value because there is little or no increase in the resistivity values obtained.

Properties of self-leveling mortars incorporating a high-volume of sugar cane bagasse ash as partial Portland cement replacement

Self-leveling mortar (SLM) is a special mortar that can flow and fill under its own weight without the need for any compaction energy. To meet these characteristics and to ensure their stability (no segregation and exudation) these mortars require, in addition to proper mixing design and the use of water reducing assets, a large quantity of fines or viscosity modifying additives, which raises the cost for the production. The use of industrial by products such as sugar-cane bagasse ash (SCBA) is an interesting alternative because they are lower cost materials and act as viscosity modifying agent, providing improvements in the rheological, physical and mechanical properties for SLM. Thus, the influence of SCBA on the rheological, physical and mechanical properties of cement-based and limestone filler (LF) mortars will be investigate in this research. The mortars were produced with a water/binder (cement + LF + SCBA) volumetric ratio of 0.85 and 15%, 20%, 25% and 30% Portland cement (PC) replacement by SCBA. An experimental study was conducted to evaluate the effects of SCBA incorporation on the properties of fresh (viscosity, flowability and filling ability) and hardened mortars (flexural strength, compressive strength, dynamic modulus of elasticity, bond strength and water absorption by capillarity). The results show that the rheological, physical and mechanical behavior of mortars was improved, especially for contents of up to 25% replacement of PC by SCBA. For higher contents, the performance of SLM was reduced.

Studi Karakteristik Campuran Tambalan Cepat Mantap (TCM)

Patching road pothole can be done using Permanent Cold Patching (PCP). This research main aim was to analyze the characteristic of the PCP. PCP Super Cold Mix Asphalt was used for the experiment. The mixtures were compacted Marshall hummer in lab using, and plate compactor on site. It was obtained that: compaction temperature variation significantly affected the characteristic of the mixture. Compaction at 100°C and 150°C, met stability, porosity and VMA specification, but not for the VFB. It required more compaction energy. The stability of cold compacted mixture at the age of 1 hour gave 844.74 kg (min. 500 kg). Towards this value, at the age of 48 hours; 96 hours; 192 hours; 384 hours, respectively gave increase of stability of 102%; 140%; 183%; 187% and then constant. Cold compaction on site gave less performance with porosity values in a range of 4.585-8.22% (spec. 4% -10%), therefore the VFB is less than minimum 65% of VMA; the stability obtained was 1422.72 kg (>min 500kg) or 58% stability of the samples compacted in lab at the same 16 days of age where stability had become maximum (constant). Cantabro test result of the cold mix gave 100% weight loss (the sample disintegrated), meanwhile the hot mix only lost 7.56% from 16% max loss.

Experimental study on electro-thermal and compaction properties of electrically conductive roller-compacted concrete overwintering layer in high RCC dams

To solve the thermal crack problem of overwintering layer of roller-compacted concrete (RCC) dams. A new type of intelligent hydraulic concrete, namely electrically conductive roller-compacted concrete (ERCC), was designed. ERCC layer could provide a new way to control the temperature distribution and reduce the cracking likelihood of RCC dams by its electro-thermal properties, closely related to the variation of resistivity of ERCC. Thus, the relationships between design factors and the resistivity were investigated to obtain the real resistivity of ERCC layer of RCC dams. Then the temperature increase of ERCC layer with the size of 3000 × 700 × 200 mm was measured under 30 V direct current voltage. The temperature rises 14 ~ 16 ℃ within 235 min. It means that the electro-thermal properties of ERCC are enough to resist cold waves in winter. On the other hand, the mechanical and compaction properties of ERCC were investigated through experiments to evaluate whether the roller compaction method can overcome the poor fluidity and improve the construction quality of ERCC. So the density and strength of roller compacted device formed ERCC were compared with those of vibration formed ERCC, which shows the superiority of rolling construction method. According to unit compaction energy and parameters of the roller machines, the onsite compaction passes NS are calculated, which provides guidance for the construction of overwintering layer. In summary, selecting ERCC as the overwintering material instead of traditional thermal insulation materials could provide a more flexible and intelligent temperature control way for RCC dams in the severe cold areas, signifying ERCC is a promising material in hydraulic engineering.

Incorporation of recycled concrete aggregate (RCA) fractions in semi-dense asphalt (SDA) pavements: Volumetrics, durability and mechanical properties

Recycled Concrete Aggregates (RCA) form a significant part of construction and demolition waste and its recycling is crucial for long-term construction sustainability. This study examined the incorporation of various fractions of RCA in Semi-Dense Asphalt (SDA) mixtures. The control SDA aggregates were replaced by RCA in selected fractions of 2/4 mm (coarse) and 0.125/2 mm (sand) at 100% and 50% each, and the filler at 100% of the fraction. The replacement was performed by mass with only one fraction being replaced for any single mixture. The mixtures were evaluated by their volumetrics, indirect tensile strength (ITS), water sensitivity (EN 12697-12), fracture energy and rutting resistance (EN 12697-22), in order to assess the effects of each RCA fraction on the mixture properties. The results showed that RCA coarse aggregates absorb significant amounts of binder and require more energy for compaction, which is not the case for the RCA sand or filler. The ITS results showed increased peak load for the RCA replacement samples but also increased brittleness in terms of resistance to crack initiation and propagation. RCA sand incorporation decreased the fracture energy at a higher rate than the coarse per total amount replaced. The ITSR% was similar to the control for lower amounts of RCA replacement, but significantly lower with higher replacement. The rutting resistance improved with RCA sand and especially coarse aggregate replacement. The study shows some limitations for use of RCA in asphalt mixtures, but also the potential for using them when the replacement rate is limited and replacement by volume is recommended. The RCA filler performance was very similar to the virgin filler, which makes its use in asphalt mixtures especially promising.

MICROSTRUCTURAL INVESTIGATION AND STRENGTH PROPERTIES OF CLAY STABILIZED WITH CEMENT, RICE HUSK ASH AND PROMOTER

A clay soil, classified as Clay of High plasticity (CH) according to Unified Soil Classification System (USCS) was stabilized with cement, Rice Husk Ash (RHA) and promoter. The mineralogy of the clay soil and the morphology of the clay and clay specimens admixed with varied composition of cement, RHA and promoter were evaluated in order to determine effect of the RHA on promoter stabilization of cement based clay soil. The promoter used in this study consists of calcium chloride and sodium hydroxide in the ratio of 1:1. The clay was remolded at standard Proctor compaction energy and the specimens were mixed with 0, 1.0, 2.0 and 3.0% cement, admixed with 1.0, 2.0, 3.0% RHA each, and 0.3, 0.6, 1.0% promoter each. The molded specimens were cured for 1, 7, 14, 28, 60 and 90days before testing for Unconfined Compressive Strength (UCS) and consequently the modulus of elasticity. The UCS of specimens without cement increased from 20 kN/m2 for the natural clay soil to 95 kN/m2 on addition of 3% RHA and 1.0% promoter after 28 days of curing, representing 475% increase in the UCS. This increase was confirmed by morphology of the clay soil mixed with RHA and promoter only, which showed presence of calcium silicate hydrate. Addition of 3.0% cement with 3 and 1.0% RHA and promoter respectively, increased the UCS from 220 to 375kN/m2 after 28 days of curing, which was also confirmed by the morphology of the specimens. The highest elastic modulus of 48.3 MPa was observed at specimens containing 3% cement, 3% RHA and 1.0% promoter.

High performance prediction of soil compaction parameters using multi expression programming

Previous prediction models for soil compaction parameters were developed using limited data of specific soils and their accuracy also needs to be improved. This study presents the development of a new prediction model for the soil compaction parameters (i.e. optimum water content and maximum dry density) using the multi expression programming (MEP). Numerous soil compaction tests with a wide range of soil classifications and compaction energies are first collected to form a large database. Then, the optimal setting of the MEP code parameters is investigated and determined. The explicit formulations for the two key compaction parameters are finally proposed. The validity and the sensitivity analysis of the model are conducted. The results show that the proposed model enables to predict the soil compaction parameters for all kinds of soils in the database with high accuracy. The monotonicity analysis of the predicted compaction parameters with each input property (four physical properties of soil and one compaction energy) verifies the correctness and the validity of proposed model, showing consistency with the monotonicity concerning the actual data in the database. From the sensitivity analysis about the relevance of each input property on the predicted compaction parameters, it is indicated that the plastic limit and the fines content have more significant influences on the prediction results, while the effect of the liquid limit is the least pronounced.

Interaction Between a Lateritic Soil and a Non-woven Geotextile in Different Moisture Conditions

This work evaluates the increase in stiffness provided by the variation of moisture content (matrix suction) and the grain size structure at the interface between a cohesive tropical soil (lateritic clay) and a nonwoven geotextile. For this purpose, monotonic pullout tests with soil suction monitoring were performed on small-sized equipment under three scenarios (O Optimum, D Dry and DP Dry Post-Compaction) and two vertical pressures (14 and 28 kPa). The Dry Post-Compaction tests were conducted with the same matrix suction of the Dry tests. The monotonic pullout tests evaluated the soil-geosynthetic interaction under constant displacement to calculate the apparent confined stiffness of the geosynthetic (Jc). The Wide Width Tensile tests were conducted to assess the unconfined stiffness of the nonwoven geotextile (Jn). The Dry scenario, compacted with higher compaction energy than the others and, consequently, altering its grain size structure, presented the best performance. This indicates that other parameters besides the suction may be influencing the interaction between the soil and the non-woven geotextile. Even under small vertical pressures, the apparent confined stiffness improves considerably compared to the unconfined stiffness. This indicates that the use of the unconfined stiffness obtained by index tests may be a conservative measure in paving projects.

Size-dependent biochar breaking under compaction: Implications on clogging and pathogen removal in biofilters

Breaking of biochar during compaction of amended soil in roadside biofilters or landfill cover can affect infiltration and pollutant removal capacity. It is unknown how the initial biochar size affects the biochar breaking, clogging potential, and contaminant removal capacity of the biochar-amended soil. We compacted a mixture of coarse sand and biochar with sizes smaller than, similar to, or larger than the sand in columns and applied stormwater contaminated with E. coli. Packing columns with biochar pre-coated with a dye and analyzing the dye concentration in the broken biochar particles eluted from the columns, we proved that biochar predominantly breaks under compaction by disintegration or splitting, not by abrasion. Increases in biochar size decrease the likelihood of biochar breaking. We attribute this result to the effective dissipation of compaction energy through a greater number of contact points between a large biochar particle and the adjacent particles. Most of the broken biochar particles are deposited in the pore spaces of the background geomedia, resulting in an exponential decrease in hydraulic conductivity of amended sand with an increase in suspended sediment loading. The clogging rate was higher in the columns with small biochar. The columns with small biochar also exhibited high E. coli removal capacity, partly because of an increase in bacterial straining at reduced pore size after compaction. These results are useful in selecting appropriate biochar size for its application in soils and roadside biofilters for stormwater treatment.

Application of diluted methanol to allow the production of latex modified asphalt mixture with lower energy consumption

The modification of asphalt mixtures using latex has gained popularity in the asphalt industry as it improves the durability of road pavement. However, the elastomeric properties of latex stiffen the binder, resulting in more energy consumption during the asphalt mixture production. It would consequently cause a higher emission of greenhouse gases, which is undesirable for the human health and environment. This study aims to assess the applicability of diluted methanol as a foaming agent in asphalt mixture incorporating latex produced at a lower temperature. In this study, two designated amounts of diluted methanol (1% and 3% of the weight of asphalt binder) were successively injected with 6% latex into pre-heated asphalt binder at 135 °C in the preparation of foamed binders, while the control and latex modified asphalt mixtures were prepared at 160 °C. Tests of rotational viscosity, expansion rate, and torsional recovery were conducted to study the rheological properties of the mixtures. Service characteristics were evaluated through the indices of workability, compaction energy, and coatability. Moreover, mixture performance tests were carried out to identify the tolerance of the mixtures towards moisture damage, shear force, and permanent deformation. Through the rotational viscosity test, diluted methanol was found to reduce the viscosity of the asphalt binders, which is vital in the production processes at intermediate temperatures. The enhancement in viscosity using 3% diluted methanol had facilitated in higher workability, lower compaction energy, and better aggregate coating, which are the crucial criteria for a better mixing and compaction process. Whereby, a superior foaming quality was exhibited from the 3% diluted methanol application through the assessments of expansion ratio, half-life and foaming index. The moisture and shear resistances of the diluted methanol foamed asphalt mixtures are comparable to the control mixtures even though they were prepared at a lower temperature. Finally, the 3% diluted methanol foamed asphalt mixture promoted a better rutting resistance due to its ability to recover to the initial form which was demonstrated through its torsional recovery.

Compaction delay and its effect on the geotechnical properties of lime treated semi-arid soils

Quality construction control requires ensuring that compacted fills are properly placed without any significant delay between mixing and compaction of the wet soil mixture. When chemical treatment is resorted to meet the shortcomings in the use of locally available materials, the delay in compaction (time elapsed between mixing and compaction of the wet soil mixture) plays a significant role as it dictates the final in-site density values achieved. In this study, the effect of delay in compaction on the density and moisture content relationships was evaluated for the delay periods of 1hr, 4hr, 24 hr and 7 days. The study was even extended to lime treated soils (at 2% and 4% by dry weight of soil). The time lag which occurs immediately after the onset of wet mixing and compaction often results in variation in geotechnical properties. Accordingly, an attempt was also made to study the effect of delay in compaction on the hydraulic conductivity, compressibility and unconfined compressive strength (UCS) behaviour of plastic clays sourced from the semi-arid region. In order to understand the variations in microstructure, MIP tests (Mercury Intrusion Porosimetry) were conducted at higher delay periods when treated with lime. From the results, it was observed that delay in compaction led to an increase in the hydraulic conductivity and compressibility of both soils. Furthermore, the UCS of both the soils showed a decreasing trend with the increase in the delay period. The agglomeration of clay particles leads to the formation of clods at higher delay periods which resist the compaction energy resulting in reduced density values which in-turn affect the geotechnical properties.

COMPACTION CHARACTERISTICS OF A FINE-GRAINED SOIL POTENTIAL FOR LANDFILL LINER APPLICATION

Increasing population growth and urbanization results in increased demand for waste disposal processes and facilities that can protect public health and the environment. In the Philippines, there is a great demand to construct sanitary landfills (SLF) with only 387 local government units (LGUs) or equivalent to 23.86% compliant to date with Republic Act 9003 which mandates all LGUs to use the sanitary landfill. The compaction characteristics of a locally abundant fine-grained soil at different compaction energy levels were investigated as part of a broader study in the suitability of the soil as a landfill liner material. Compaction is essential in the preparation of a well-compacted soil liner in a sanitary landfill to avoid or minimize the migration of leachate and thereby reduce the risk of groundwater pollution. The physical properties are determined through a series of laboratory tests which covers the grain-size distribution, specific gravity, Atterberg limits, soil classification, XRD and SEM-EDX. Correlations to estimate the compaction characteristics at any rational compaction energy (E) are developed. The maximum dry unit weight values at different compactive efforts were used to determine void ratios which were then utilized to compute for the saturated hydraulic conductivity using numerical model for hydraulic conductivity for the same soil type. The resulting hydraulic conductivity ranges from 2.30 x 10-7 to 1.20 x 10-7 cm/sec well above the required value in the Philippines as per RA 9003 and its IRR for the intended Category I and II SLFs application

Influence of Energy on Compaction Characteristics of High Expansive Soils

Each soil type has different behavior with regard to determination of maximum dry density and optimum moisture content and therefore any soil type has its own compaction requirements for experimental purposes and for control the compaction in the field. The general purpose of this study is to a better understanding of the compaction characteristics of high expansive soils, with emphasis on the relationships of moisture content and dry density of high expansive soils at a range of compaction energy levels. To achieve this purpose, high expansive soils samples were subjected to Atterberg limit and a set of laboratory compaction tests to find compaction characteristics namely; maximum dry unit weight and optimum water content of high expansive soils at different compaction energy (compaction effort) for different number of hammer blows per each layer range from 10 to 50, which varied the energy per unit volume from 356 KN/m3 to 1188 KN/m3.Rather than single peak compaction curves, the most achieved compaction curves are an irregular one and half peak compaction curves. According to the comparison results of different compaction energy, it was concluded that the maximum dry unit weight of high expansive soil was not highly affected by gradually increase of applied energy. The results showed that, the maximum dry density of tested expansive soils sample increased from 1.48g/cm3 to 1.6g/cm3 with increase of compaction energy from 356 KN/m3 to 1188 KN/m3.

Physical characterization of bio-composite CEB stabilized with Argan nut shell and cement

Compressed earth blocks (CEB) are a well-established constructional material in the world’s less developed countries. The most common weakness of earthen construction is their high rate of deterioration under water.The aim purpose of this work is to upgrade the behavior of stabilized blocks of earth blocks against water attacks by studying experimentally the properties of the composite that is made from CEB and vegetable wastes in Morocco: Argan nut shell powder (ANS). The water absorption behavior has been estimated for the new bio-composite. The tested natural load contents are: 0%, 2%, 4% and 6%. To examine the effect of chemical stabilization on the new material, dosages of 0%, 5% and 6% of cement was also tested.This work highlights the procedure of soil-stabilization and the contributions of soil’s structure during stabilization. It investigated the quasi-static process of conventional block compaction (slow-applied pressure) and established the effects obtained from the alteration of the components (ANS and cement) and the compaction energy (2 MPa and 4 MPa) on the dry density of CEBs.

Correlation of compaction characteristics of standard and reduced Proctor tests

Analysis of reduced Proctor test and standard Proctor test results collected from literature indicates that it is possible to replace standard Proctor with reduced Proctor due to the advantages that the reduced Proctor test requires 40% less compaction energy, requires no modifications to the standard Proctor compaction apparatus unlike other small compaction tests, and the soil particle size requirements remain the same as those for the standard Proctor test. Correlations were also developed for compaction characteristics obtained by the modified Proctor test and the reduced Proctor test in order to estimate compaction characteristics at the modified Proctor energy level by just performing the reduced Proctor test. The optimum moisture content was found to correlate well with liquid limit. In addition, for the reduced Proctor test, maximum dry density was found to have a very good correlation with optimum moisture content.

Comparison of Reduced Modified Proctor vs Modified Proctor

The compaction characteristics between reduced modified Proctor and modified Proctor tests have been compared. The results show that maximum dry unit weight values are comparable for both the tests but optimum moisture content values differ slightly more. For both the tests: optimum moisture content was found to correlate best with liquid limit, and the relationship for maximum dry unit weight with optimum moisture content was found to be almost the same. Since reduced modified Proctor requires less time and 40% less compaction energy as compared to modified Proctor test, it can be considered as a suitable alternative to the modified Proctor test.