Environment- Friendly Construction Materials

He has supported more than 100 graduate students and more than 15 postdoctoral scholars and conducted research for many agencies (eg, the Federal Highway Administration (FHWA)). The results were compared with those obtained for the reference samples prepared from traditional aggregates (the analysis of the available mineral asphalt mixtures (MAM) research results based on the traditional aggregates).

Materials and Methods 1. Material Properties

VMA-corresponds to the content of voids in the mineral mixture, expressed in %, which can be calculated by means of equation (8) [24]. The first group of similar samples is the "wet" samples, while the other - the "dry" ones.

Figure 1. Images of aggregate grains structure: (a) obtained from sanitary ceramics, (b) dolomite, (c) granodiorite, (d) basalt, (e) sand ( × 1500).

Results

Mixes prepared with only dolomite (WC-4) had the lowest voids and were 39% lower than WC-3 MAM. On the other hand, the void in the mineral mixture filled with binder should not be lower than 75% and higher than 93%.

Table 9. Aggregate graining following extraction for WC-2.

Conclusions

On the other hand, wide cracks appeared in the mixture with granodiorite, increasing the void content in MAM and decreasing the bulk density of the mixture. BS EN IDT], Bituminous mixtures - Test methods for hot mixed asphalt - Part 23: Determination of indirect tensile strength of bituminous samples; British Standard, BSI: London, UK, 2003.

The Wastes of Sanitary Ceramics as Recycling Aggregate to Special Concretes

Introduction

In the research conducted by [17], two concrete mixes were prepared in the ratio 1:2:4 (cement:sand:coarse aggregate). Prepared concretes were characterized by similar properties to those based on natural coarse aggregates.

Materials and Methods

In the samples of concrete baked at 20◦C (C10_20), as a result of the hydration process, hydrates appear, the chemical content of which is similar to C3AH6(katoite) and AH3(gibbsite). In the case of samples made of calcium aluminate cement, a total of 45 samples were examined.

Table 1. The comparison of prepared concrete mixes in 1 m 3 of concrete mix.

Excellent Carbonation Behavior of Rankinite

Prepared by Calcining the C-S-H: Potential Recycling of Waste Concrete Powders for Prefabricated

Building Products

The cubic compressive strengths of compressed C3S2 samples carbonized for 24 hours and 24 hours, respectively, are shown in Figure 1. Figures 5 and 6 show SEM-EDS images of compressed C3S2 samples before and after carbonization.

Figure 1. The compressive strength of compacted C 3 S 2 samples with different carbonation times.

Feasibility Evaluation of Preparing Asphalt Mixture with Low-Grade Aggregate, Rubber Asphalt and

Materials and Research Methodologies 1. Materials

Hot water damage test and freeze-thaw damage test were performed according to the Chinese standard methods [29]. The tensile strength ratio (TSR) parameter, which reflects resistance to freeze-thaw damage of asphalt mixture, was calculated according to Equation (2).

Table 1. Combination of raw materials types for each mixture.

Results and Discussions

It suggested that the DGR and RMA can both improve the breaking energy of asphalt mix. It clearly shows that the DGR deteriorated the high temperature deformation resistance of the asphalt mixture.

Table 3. Basic technical properties of fillers.

Laboratory and Field Investigation of the Feasibility of Crumb Rubber Waste Application to Improve the

Asphalt Pavement

• Materials and Experimental Methods 1. Materials
• Field Test Road and Evaluation
• Results and Discussion 1. Laboratory Results
• Conclusions

With the addition of ARA, ITS increased to nearly twice that of the base asphalt mix. Such results indicate that the addition of ARA improved the asphalt mix's resistance to vertical loading. This shows that adding CR can improve the elasticity of the track-resistant asphalt mixture.

The properties of the asphalt mixture used in the test road are listed in Table 8. The flow rate of the CR-modified anti-rutting mixture was slightly lower than that of the base asphalt mixture. This phenomenon indicates that the integrated modification led to the increased strength of the asphalt mixture and contributed to the asphalt pavement performance at high temperatures.

Table 1. Physical and chemical properties of bitumen.

Adhesion between Asphalt and Recycled Concrete Aggregate and Its Impact on the Properties of

Asphalt Mixture

• Introduction Research Background
• Raw Materials and Mixtures 1. Raw Materials
• Experimental Methods
• Results and Discussion

Then, the effects of the adhesive on water stability and fatigue resistance were analyzed. According to the surface energy parameters of water and ethanol (Table 3) and the CA between aggregates and asphalts (Table 6), the surface energy parameters between different solid bitumens and aggregates can be solved by Equation (8), as shown in Table 7. According to the surface energy parameters of asphalt (Table 7) and the CA between aggregates and liquid asphalts (Table 8), the adhesion strength of liquid asphalts and aggregates can be calculated by Equation (8), as shown in Table 9.

Therefore, the aqueous stability of HMA-RCA is worse than that of the traditional mixture. As the RCA content increases, the water stability of asphalt concrete is generally weakened. Therefore, when the aggregate contains more RCA, the anti-fatigue performance of the HMA-RCA will decrease.

Table 1. Technique performance of asphalts.

Effects of Cement and Emulsified Asphalt on Properties of Mastics and 100% Cold Recycled

Materials and Methods 1. Materials

The properties of the matrix asphalt and the emulsified asphalt are listed in Table 1 and Table 2, respectively. In this study, RAP was collected from the revised milling materials of Qingdao Jiaozhou Bay Highway. After the extraction, the above mentioned mineral filler and fine aggregates separated from the surface of the RAP.

After cement is added to the CRAM, it will hydrate with some of the water in the mixture and form hydration products. Combined with the solids content of the emulsified asphalt and the amount of cement, the FBR of the cement residual mastic was calculated (Table 6). The applied stress and the resulting recoverable axial stress response of the samples were measured and used to calculate the dynamic modulus and phase angle according to equations (2)-(5).

Table 3. Results of sieving for RAP

Results and Discussion 1. Properties of Mastics

With amounts of emulsified asphalt of 3.5% and 4.5%, the modulus of the mastic increased with increases in FBR. It can be seen that the B value of the mineral filler asphalt mastic was higher than that of the mineral filler residue mastic. The B value of the cement-residue mastic first decreased and then increased with increases in FBR.

Based on the above research into the rheological properties of mastic, the influence of the emulsified asphalt content on the rheological properties of CRAM was evaluated. Based on the above research into the rheological properties of cement-residual mastic, the influence of the cement content on the mechanical properties of CRAM was evaluated. This is because the hydration of cement helps to increase the elastic solid properties of the cement residue mastic.

Figure 3. Relationship between mastic modulus and FBR. (a) Mineral filler-asphalt mastic (b) Mineral filler-residue mastic (c) Cement-residue masticAs can be seen in Figure 3, the modulus of the three types of mastics were all higher than those of matrix asp

Enhancement of Dynamic Damping in Eco-Friendly Railway Concrete Sleepers Using Waste-Tyre

Crumb Rubber

• Railway Applications
• Methods
• Materials
• Experimental Results and Discussion
• Conclusions

Different proportions of crumb rubber with different particle sizes (75, 180 and 400μm) were used to analyze their effects on the compressive strength, tensile and flexural strengths, electrical resistance and damping properties of the rubber concrete. However, the dynamic test data of crumb rubber concrete is not enough for concrete sleeper design. Silica fume is used as a partial replacement of the cement content and the crumb rubber as an alternative aggregate by replacing different amounts of fine aggregates.

It is clear that the addition of crumb rubber negatively affected the performance of the concrete, while the silica fume improved it. Similarly, a significant deterioration in both split tensile and flexural strength has been observed when increasing the crumb rubber content in concrete. Surface modification of rubber crumbs and its influence on the mechanical properties of rubber cement concrete.Constr.

Figure 1. Components of railway tracks.

Effect of Modified Polyvinyl Alcohol Fibers on the Mechanical Behavior of Engineered

Cementitious Composites

Materials and Methods 1. Raw Materials

The fundamental proportions of the produced cementitious composites included cement, fly ash and quartz sand. Pre-calculated and pre-weighed PVA fibers were added and soaked under constant stirring, with the simultaneous application of the ultra-sonicator for 10 min. The study used a rotor-type viscometer to test the rheological properties of the cementitious composite slurry.

The tested shear stress range was 6–200 Pa, and the shear rate could be infinitely variable in the range of 0–1000 rpm. Once the specimen for tensile testing was prepared, aluminum LVDT (linear variable differential transformer) clamps were configured and securely attached to the tensile region of the specimen. Displacement sensors (model: SCAH series, Abek Sensors Co., Ltd., Beijing, China) were placed on both sides of the tensile test sample data and provided information to a Keithley 2700 data acquisition apparatus (Keithley 2700, Keithley Instruments, Beaverton, OR, USA).

Results and Discussion

The strength rating of the engineered cement composites produced for the study was 40 MPa (see Table 8 for parameters). The introduction of boric anhydride creates a moderately significant effect on the strength of the manufactured cement composites. It is not easy to pull the fibers to break in the stretching process, and the ductility of the manufactured cement composites has been improved.

Therefore, the first crack strength can be taken as the tensile strength of cement composites. Engineered cement composites, which are made from processed fibers, do not primarily affect the strength of the composites. This means that the ductility of manufactured cement composites can be further effectively improved.

Rheological Behavior and Microstructure Characteristics of SCC Incorporating

Results and Discussions 1. Rheology Behavior

It can be seen that the slump flow and SA of SCC decrease with the increase in MK and SF content (Shown as the red arrows in Figure 6). It can be seen that the combined use of MK and SF can achieve higher fluidity with the same dosage. In general, it can be seen that the addition of MK and SF can increase the compressive strength of SCC.

The addition of MK and SF reduced the mass loss peak of Ca(OH)2, indicating that the content of Ca(OH)2 in hydration products decreases, and is consistent with the XRD results (as shown in Figure 10). Therefore, the addition of MK and SF is beneficial for refining the pore structure of SCC. The effect of MK and SF on the rheology, workability, compressive strength and microstructure is investigated.

Effects of Pumice-Based Porous Material on

Hydration Characteristics and Persistent Shrinkage of Ultra-High Performance Concrete (UHPC)

ESEM-EDS

The micro-domain morphology and surface structure of the samples are observed by a field emission QUANTA FEG 450 ESEM. At the same time, the EDS analysis can interpret the components of the micro-zone, and the intelligent quantitative results provided by eZAF help to effectively evaluate the atomic ratio of the elements of the skin layer.

Results and Discussion 1. Fresh Behaviors

• ESEM-EDS

Fluidity of the designed UHPC with different amounts of extra water introduced by wet pumice. Among them is the positive effect that the continuous release of moisture by the wet pumice stone will continuously promote the hydration of the dehydrated. Influence of moist pumice on the sustained shrinkage strain development of the designed UHPC: (a) unsaturated pumice replacement; (b) saturated pumice replacement.

To gain a better understanding of the hydration mechanism of wet pumice in UHPC, Ca(OH)2. After the introduction of the IC pumice, the content of Ca(OH)2 is significantly lowered at the age of 28 days compared to the samples at seven days; on the other hand, that of Ca(OH)2 is increased in the control group of UHPC. Development of the mechanical properties of an Ultra-High Performance Fiber Reinforced Concrete (UHPFRC).Cem.