Rubber Powder Content Research Articles

Research on the factors affecting the compressive strength of rubber powder modified cement-stabilized crushed stone based on orthogonal experiments

Based on an orthogonal experimental design, this study introduces rubber powder particle size alongside rubber powder content, aggregate gradation, and cement content as factors. A total of 16 mix proportions were formulated. For each mixture, compaction tests and unconfined compressive strength (UCS) tests were conducted. Using Statistical Product and Service Solutions (SPSS) software, a multifactor variance analysis was performed to determine the influence levels of the four factors on maximum dry density and compressive strength. The optimal mix proportion was selected based on compressive strength. The results indicate that aggregate gradation and rubber powder content significantly affect the maximum dry density of the mixture, with aggregate gradation having the greatest impact. Rubber powder content has the most substantial effect on compressive strength, while rubber particle size has the least influence. The optimal formulation is 7% cement content, 30-mesh rubber powder, 0.5% rubber powder content, and a skeletal dense gradation close to the median.

Improving the scour-resistance performance of for offshore wind turbines: Experimental and computational fluid dynamics studies on macro and micro characteristics

To enhance the resistance to local scour around offshore wind turbine monopiles, 15 mixtures were designed based on Response Surface Methodology (RSM). Cement content, sodium silicate content, and rubber powder content were selected as independent variables. After determining their flowability, the compressive strength and shear strength were measured after curing in pure water and artificial seawater for 3 days, 7 days, 14 days, and 28 days. Experimental results indicate significant improvement in the mechanical properties of the modified soil, including increased Unconfined Compressive Strength (UCS), internal friction angle, and cohesion. The optimal mix ratio is identified as CSR40–10–15, consisting of 40 % cement, 10 % sodium silicate, and 15 % rubber powder. The strength variation mechanism is elucidated from both macroscopic and microscopic perspectives. Finally, numerical simulations using Computational Fluid Dynamics (CFD) software validate the scour resistance performance based on the optimal mix ratio of flowable solidified soil, offering a new approach for local scour protection around offshore wind turbine monopile.

Mechanical Properties of Cement Concrete with Waste Rubber Powder

To investigate the mechanical properties of cement concrete incorporating waste rubber powder, the response surface methodology was employed. The Box–Behnken central composite design was applied to analyze the three primary factors influencing the road performance of cement concrete containing waste rubber powder: the water–cement ratio, sand ratio, and waste rubber powder content. The study determined the impact of these factors on the flexural strength of waste rubber powder cement concrete at both 7 and 28 days. Additionally, the effects of the water–cement ratio, sand ratio, and waste rubber powder content on the performance of cement concrete were analyzed. To investigate the impact of waste rubber powder on cement concrete, various mechanical property tests were conducted, including compressive, flexural, dynamic elastic modulus, and impact performance tests. Furthermore, the study explored the influence of waste rubber powder on the noise reduction capacity of cement concrete using both the rubber ball impact method and ultrasonic method. Lastly, the durability of cement concrete with added rubber powder was assessed through shrinkage tests, frost resistance tests, and chloride ion penetration tests.

Fracture behavior of environmentally friendly high-strength concrete using recycled rubber powder and steel fibers: Experiment and modeling

Ultra-high-performance concrete (UHPC) is becoming increasingly popular for its exceptional mechanical properties but suffers from high cost and limited ductility. To overcome these limitations, this study explores the development of cost-effective and ductile Environmentally friendly High-strength Concrete (E-HSC) by incorporating recycled steel fiber (RSF) and rubber powder into UHPC. Fracture properties and crack propagation behavior were examined through three-point bending fracture tests on notched beams with varying rubber powder (0 %, 5 %, 20 %, 35 % and 50 %) and recycled steel fiber (1 %, 2 % and 3 %) content. Digital Image Correlation method was Used to Measure Crack mouth opening displacement and Fracture process zone in the Fracture Process of E-HSC of the E-HSC were analyzed using the digital image correlation method. Results revealed that E-HSC with 5 % rubber powder exhibited superior fracture energy and double-K fracture toughness. The use of rubber powder and RSF enhances the ductility of concrete, with the characteristic length consistently increasing as the content of rubber powder and RSF increases. Additionally, a softening constitutive model was proposed to evaluate the fracture performance of E-HSC based on rubber powder and recycled steel fiber content. This research provides experimental data and theoretical insights for developing resilient E-HSC suitable for applications in significant structures.

Influence of preparation parameters on rheological properties and relation analysis of waste rubber modified bitumen mastic

Waste rubber modified bitumen has gained significant attention as a sustainable and innovative material in the field of pavement engineering. This study aims to evaluate the performance of rubber modified bitumen mastic by considering its rheological properties, specifically focusing on preparation parameters, i.e., rubber content, mesh number, and filler to bitumen ratio. From the experimental results, the rheological properties of rubber modified bitumen mastic were significantly influenced by preparation parameters. Increasing the rubber powder content in bitumen mastic results in higher viscosity. Increasing the rubber content improves high-temperature rutting resistance to a certain extent, however, excessive rubber powder content would result in weakened high-temperature performance improvement. The rutting factor decreases gradually with an increase in the rubber mesh number. A ratio of filler to bitumen of 0.95 exhibits the best resistance to rutting at high temperatures. Higher rubber content and larger mesh number correspond to stronger low-temperature crack resistance in bitumen mastic. As the ratio of filler to bitumen increases, the low-temperature deformation capacity gradually decreases, resulting in weaker low-temperature crack resistance. Based on the grey relation analysis, the ratio of filler to bitumen has the greatest impact on the high and low-temperature rheological properties of bitumen mastic, followed by the rubber content. The rubber mesh number has a relatively lower impact. It is crucial to control the ratio of filler to bitumen to avoid excessive values. When possible, a higher rubber powder content should be used while meeting process requirements. These findings provide valuable insights into the design and optimization of rubber modified bitumen mastic, which can contribute to the development of sustainable and high-performance bitumen mixtures, promoting the use of recycled rubber in pavement engineering.

Enhancing clayey soil performance with lime and waste rubber tyre powder: Mechanical, microstructural, and statistical analysis

Nowadays, for soil stabilisation and cleaner production of geo-composites, the possibility of utilizing waste rubber is in vogue. The present paper deals with experimentally investigating the mechanical and micro-structural characteristics of weak Indian clayey soil partially substituted with lime (0–3.5%) and waste rubber tyre powder (0–15%). It was observed that, with increasing lime and rubber powder content, the plasticity index of the soil decreases. The shear strength and compaction testing results reveal that adding lime and rubber tyre powder (RTP) enhances the geotechnical performance of clayey soil up to an optimum dosage value. Also, the tri-axial shear testing was performed to obtain stress-strain curves for all considered soil mixes. For modified clayey soil containing 3% lime and 12.5% rubber powder, the cohesion values and bearing capacities improved phenomenally by 36.1% and 88.6% respectively, when compared to clayey soil. Further for this mix, SEM analysis reveals a compacted microstructure which improves dry-density and California's bearing ratio among all modified mixes. The novel co-relations upon regression analysis are found able to predict plasticity index, dry density, bearing capacity and shear strength with higher confidence levels. Overall, the cost-benefit analysis worked out to obtain the optimum cost of construction of footings and flexible pavement shows cost deductions up to 19% and 39% respectively while utilizing modified clay soil mixes containing 3% lime and 12.5% rubber powder in subgrade, ultimately making production stronger, cheaper and environment friendly.

Optimum Design of Mixture Proportion and Microscopic Analysis of Cement-Stabilized Macadam by Rubber Powder and Fiber

Abstract Based on the orthogonal test method, the mixture proportion design of cement-stabilized macadam (CSM) modified with rubber powder and fiber is studied. With strength and dry-shrinkage as key indices, the influence of length of polyvinyl alcohol (PVA) fiber, fiber content, particle size of rubber powder, and rubber powder content on the performance of CSM is analyzed, and the optimum mixing proportion is determined. Based on this, the modification mechanism of CSM by rubber powder and fiber is further studied from a micro perspective. The results show that the 7-day unconfined compressive strength of CSM gradually increases with the increase of fiber length. With the increase of fiber content, the compressive strength shows a trend of first increasing and then decreasing. The 7-day unconfined compressive strength of CSM gradually increases with the increase of rubber powder mesh size and linearly decreases with the increase of rubber powder content. The 28-day average dry-shrinkage coefficient of CSM shows a trend of first decreasing and then increasing with the increase of fiber length and fiber content, and gradually increasing with the increase of rubber powder mesh number and rubber powder content. Considering the strength and shrinkage characteristics, the optimum mixing parameters are 40 mesh rubber powder, 0.5 % rubber powder, 18-mm fiber length, and 1.2-kg/m3 fiber content. Scanning electron microscopy results show that there is a gap between the rubber powder and the cement matrix, and the interface between the two is discontinuous, with weak bonding, resulting in a decrease in the compressive strength of CSM. PVA fiber can improve the toughness of CSM. It has good adhesion with cement matrix. It forms a three-dimensional network support structure in the CSM mixture and can restrain water loss in the cement matrix, thus greatly improving the cracking resistance of CSM.

Dynamic uniaxial compression mechanical properties of self-compacting rubber concrete subjected to different strain rates

Rubber concrete is a kind of light green building material, which is prepared by mixing rubber powder or rubber crumb into ordinary concrete in a certain proportion and then introducing rubber concrete through vibration-free technology to prepare self-compacting rubber concrete. Uniaxial compression tests were carried out on self-compacting rubber concrete with two particle sizes at different strain rates, and the effects of strain rate and rubber content on the dynamic mechanical properties of self-compacting rubber concrete were studied. The microstructure of self-compacting rubber concrete before and after damage was analyzed. Compared with ordinary concrete, the self-compacting rubber concrete is capable of maintaining good integrity during damage, when the rubber powder content exceeds 10% and the rubber crumb content exceeds 15%. The results indicate that as the strain rate increases, both the peak stress and the elastic modulus increase, indicating the strain rate enhancement effect, while the strain rate effect of the peak strain is not evident. Moreover, the model equations of peak stress and elastic modulus strain rate effect were established, the dynamic damage constitutive model was proposed, the damage evolution was analyzed, and the stress intervals were assigned to the various stages of damage evolution.

Laboratory proportion design and performance evaluation of Fiber-Reinforced rubber asphalt chip seal based on multiple properties enhancement

Chip seal is an effective preventive maintenance technology for the pavement distress repair and pavement service life extension. Adding fiber or rubber powder alone has been shown to improve chip seal performance. However, the full potential of chip seal could not be attained by utilizing only fiber or rubber powder singularly. In this study, a fiber-reinforced rubber asphalt chip seal was prepared and evaluated based on multiple properties enhancement. Analysis of Variance (ANOVA) was conducted to assess the level of significant influence of rubber powder content and shearing time on the results of the penetration, softening point, ductility, and elastic recovery tests. The optimal process parameters for rubber asphalt were further analyzed and determined based on the ANOVA results. Bending beam rheometer (BBR) and rotational viscosity tests were executed to evaluate the low-temperature crack resistance and workability of the rubber asphalt. Cover, sweep, 45-degree skew shear and texture depth tests were performed to identify the optimum proportion of fiber-reinforced rubber asphalt chip seal. Tensile, temperature stability, water stability and three-point bending tests were conducted to evaluate chip seal performance. Cost analysis for mature preventive maintenance technology was carried out to evaluate equivalent annual costs. The results show that essential parameters for preparing rubber asphalt were the rubber powder content of 22.5% and the shearing time of 60 min. Moreover, the optimum proportion of fiber-reinforced rubber asphalt chip seal was determined to be 9.55 kg/m2 of aggregates, 2.3 kg/m2 of rubber asphalt, and 80 g/m2 of fiber. This study also confirmed that the fiber-reinforced rubber asphalt chip seal outperformed the rubber asphalt chip seal in terms of crack resistance, skid resistance, bonding performance, temperature stability, water stability and fatigue resistance. Combined with cost analysis, it was found that the fiber-reinforced rubber asphalt chip seal was a type of cost-effective preventive maintenance technology.

Compression-shear performance of steel fiber reinforced rubber concrete

Rubber powder can be produced from waste tires through processing and its inclusion in concrete, either with steel fiber or alone, has been shown to improve impact and shear toughness and reduce environmental pollution. However, the mechanical behaviors and failure criteria of steel fiber reinforced rubber concrete (SFRRC) under combined compression-shear loading, which is essential for structural application, is lacking. This study investigates the compression-shear properties of SFRRC, considering steel fiber and rubber powder content, and compressive stress ratio. The effects of these parameters on shear strength, shear peak displacement, and shear toughness were analyzed. Results indicate that as the compressive stress ratio increases, SFRRC's failure pattern changes from tensile failure to compression-shear failure when k ≥ 0.4, exhibiting ductile failure. The equivalent initial energy density increases with rubber powder content, while equivalent shear residual toughness increases after the peak value, but shear strength and peak displacement decrease. With the addition of steel fiber, initial shear strength, peak displacement, and equivalent residual strength increase. A calculation criterion for compression-shear strength was proposed, with theoretical values matching well with experimental values.

Axial compressive behavior of environmentally friendly high-strength concrete: Effects of recycled tire steel fiber and rubber powder

Ultra-high-performance concrete (UHPC) has ultrahigh strength and excellent durability but its widespread application is limited by its high cost and carbon emission. In this study, an environmentally friendly high-strength concrete (E-HSC) with low CO2-e emission was developed with the utilization of recycled tire steel fiber and rubber powder. The axial compressive behavior of E-HSC was investigated with recycled rubber powder partially replacing fine aggregates (0%, 5%, 20%, 35%, and 50%) and varying recycled steel fiber content (1%, 2%, 3%). The physical and mechanical properties of E-HSC were analyzed and compared with normal UHPC and high-performance rubberized concrete. The results show that the compressive behavior of E-HSC is determined by the mechanical properties and interaction among the rubber, cement matrix, and recycled steel fiber. Under the condition of rubber powder content (≤5%/≤ 35%), the compressive strength of E-HSC can still achieve the standard of ultra-high/high-performance concrete (≥120 MPa/≥ 50 MPa), of which ductility and toughness index were enhanced. A new constitutive model was proposed to describe the stress-strain behavior of E-HSC by considering the contents of recycled steel fiber and rubber powder. This study provides test data and design theory for the development of E-HSC.

Effects of waste rubber powder and resin content on the free shrinkage of polymer concrete

In this study, the effects of waste rubber powder (WRP) and resin content on the free shrinkage of vinyl resin polymer concrete (PC) were investigated for use in corrosive environments, such as wet flue gas desulfurization (WFGD). The mechanical properties, free shrinkage performance, microstructure, and pore structure of PC were examined with varying levels of WRP (0%, 2.5%, 5.0%, and 7.5% of binder volume) and resin content (23.1%, 24.7%, and 26.2% of total volume). The results indicated that increasing the proportion of resin in the PC material led to an enhancement in the strength of the samples. However, it was observed that high resin contents resulted in a significant increase in shrinkage. Specifically, when the resin content was elevated, the volume of the resin increased by 3% and shrinkage increased by more than 14%. Conversely, the inclusion of WRP had a negative effect on the mechanical strength but significantly reduced the shrinkage rate and exothermic peak during the curing process by over 50%. The primary factors found to be responsible for the reduction in shrinkage of PC is that the inclusion of WRP resulted in the formation of an appropriate air void system and the stress relaxation owing to the retardation of resin curing. Overall, the study revealed that WRP is a promising and sustainable filler for shrinkage reduction in PC, particularly in corrosive environments.

Bond performance and bond-slip constitutive model for rebar embedded in rubber powder-modified polypropylene fiber reinforced concrete

The bond performance and bond-slip constitutive model for rebar embedded in polypropylene fiber concrete modified by rubber powder (RPFC) are studied in this paper. 99 specimens are casted for pull-out test in order to investigate the failure mode and full bond-slip process, which are designed on the parameters of rubber powder content (0, 5%, 10% and 15%), polypropylene fiber content (0, 0.5%, 1% and 1.5%) and W/C. In order to quantitatively study the bond stresses distribution along the anchorage length, three types rebar including full cross-section, half cross-section, and inside-grooved are adopted. On the basis of the results of bond stresses distribution along the anchorage length, anchorage position function is accomplished. In this paper, the crack propagation of RPFC and plain concrete and full-field rebar strain are monitored by digital image correlation (DIC) technique. According to the experimental conclusions, a refine bond-slip constitutive model for RPFC is developed in consideration of anchorage position function. The bond-slip correlation between RPFC and the rebar could be precisely depicted by the proposed model.

Foamed crumb rubber asphalt binder: Preparation, rheological properties and adhesion characteristics

In this study, the rheological properties and adhesion characteristics of foamed CRA binder were studied. Firstly, the optimum foaming conditions of foamed CRA binder with different crumb rubber powder (CRP) content and foaming agent were studied. Secondly, stress creep recovery (MSCR) test, temperature scanning and frequency scanning tests were carried out by using dynamic shear rheometer (DSR), and the high temperature performance, temperature sensitivity and viscoelastic characteristics of each asphalt binder sample before and after aging were studied. Finally, the surface free energy theory was used to evaluate the adhesion characteristics of each sample. The results showed that the commonly used foaming agent cetyl trimethyl ammonium bromide has no effect on the foaming of CRA binder. With the increase of CRP content, the foaming temperature became higher, and it was difficult to foam successfully when the rubber powder content was higher than 15%. Increasing the content of CRP in a certain range can improve the high temperature performance and adhesion of foamed CRA binder and reduce its temperature sensitivity. With the aging process of the sample, the high temperature performance of foamed CRA binder increased, and the temperature sensitivity and adhesion characteristics decreased. The surface free energy of foamed CRA binder is mainly composed of dispersion component, and the polarity component is relatively small. The surface free energy of foamed CRA binder increased with the increase of CRP content. In addition, foaming agent B (water-in-oil emulsifier) would reduce the temperature sensitivity and high-temperature performance of foamed CRA binder, but it had no obvious effect on adhesion.

Mechanical Properties of Self-Compacting Rubberized Concrete with Different Rubber Types under Triaxial Compression

Different rubber aggregates lead to changes in the effect of stress conditions on the mechanical behavior of concrete, and studies on the triaxial properties of self-compacting rubber concrete (SCRC) are rare. In this study, 35 cylindrical specimens taking lateral stress and rubber type as variables were prepared to study the fresh properties and mechanical behaviors of SCRC under triaxial compression, where the rubber contains two types, i.e., 380 μm rubber powder and 1–4 mm rubber particles, and four contents, i.e., 10%, 20% and 30%. The test results demonstrated that SCRC exhibited a typical oblique shear failure mode under triaxial compression and had a more moderate descending branch compared with self-compacting concrete (SCC). The presence of lateral stress can significantly improve the compression properties, including initial elastic modulus, peak stress and peak strain, with an improvement range of 3%–73% for peak stress. While rubber aggregates mainly targeted the deformation abilities and toughness for improvement, and the peak strain improvement ranges were 0.1–3.1 times and 0.1–1.0 times for SCRC containing rubber powder and SCRC containing rubber particles, respectively, relative to SCC. At a high lateral stress of at least 12 MPa, the loss of strength due to the addition of rubber can be controlled within 10%, in which case the content of rubber powder and rubber particles was recommended to be at most 20% and 30%, respectively. Based on the Mohr-Coulomb theory, the failure criteria of SCRC with different rubber types were established. For analysis and design purposes, an empirical model was proposed to predict the stress-strain behavior under triaxial compression, considering the influence of different rubber content and lateral stress. The results obtained in this study can provide a valuable reference for the design and application of self-compacting rubberized concrete in practical projects, especially those involving three-way compression states and requiring high-quality deformation and energy dissipation.

Thermal and Mechanical Properties of Concrete Incorporating Silica Fume and Waste Rubber Powder.

Using waste rubber tires for concrete production will reduce the demand for natural aggregate and help to reduce environmental pollution. The main challenge of using waste rubber tires in concrete is the deterioration of mechanical properties, due to poor bonding between rubber and cement matrix. This research aims to evaluate the mechanical and thermal properties of rubberised concrete produced by using different proportions of rubber powder and silica fume. Ordinary Portland cement was partially replaced with silica fume by amounts of 5%, 10%, 15% and 20%, while sand was replaced by 10%, 20% and 30% with waste rubber powder. Tests were carried out in order to determine workability, density, compressive strength, splitting tensile strength, elastic modulus, thermal properties, water absorption and shrinkage of rubberised concrete. The compressive strength and splitting tensile strength of concrete produced using waste rubber powder were reduced by 10-52% and 9-57%, respectively. However, the reduction in modulus of elasticity was 2-36%, less severe than compressive and splitting tensile strengths. An optimum silica fume content of 15% was observed based on the results of mechanical properties. The average shrinkage of concrete containing 15% silica fume increased from -0.051% to -0.085% at 28 days, as the content of waste rubber powder increased from 10% to 30%. While the thermal conductivity of rubberised concrete was reduced by 9-35% compared to the control sample. Linear equations were found to correlate the density, splitting tensile strength, modulus of elasticity and thermal conductivity of concrete with silica fume and waste rubber powder.

Evolution mechanism of compression deformation of carbon black reinforced epoxy resin composites

AbstractIn this paper, the double‐element composites were developed, which contained the epoxy resin as matrix phase and carbon black rubber powder as toughening materials. Quasi‐static compression tests on epoxy resin and different mass fractions carbon black rubber powder‐epoxy resin composites were performed in room temperature to test their compression properties. The energy absorption performance and the energy absorption efficiency of the composites were calculated according to the compression curve. The fracture characteristics of the micro appearance of the compressed material specimen were observed by scanning electron microscope. The deformation mode of the composite was analyzed. By systematically analyzing the effects of carbon black rubber powder content on the mechanical properties of carbon black rubber powder‐epoxy resin, it was found that carbon black rubber powder as a reinforced material could effectively improve the brittleness of epoxy resin, the yield strength and the adsorption properties and efficiency of composites. With the mass fraction of carbon black rubber powder increasing, the energy absorption performance of carbon black rubber powder‐epoxy resin first increases and then decreases. The most significant performance observed was at a mass fraction of 5 % in carbon black rubber powder‐epoxy resin composites.

Fracture behavior of polypropylene fiber reinforced concrete modified by rubber powder exposed to elevated temperatures

• Elevated temperature tests conducted on RPFC notched beams. • Effect of different temperature on the fracture behavior of RPFC was studied. • The damage evolution within the fracture process zone was monitored by AE and DIC. • Fracture energy and fracture toughness first increase and then reduce with increasing temperature. In this paper, the deterioration of fracture properties of rubber powder modified polypropylene fiber concrete (RPFC) after elevated temperatures is discussed. Three-point bending tests were conducted on 75 notched beams to discuss the effects of rubber powder content (0%, 5%, 10%, 15%), polypropylene fibers content (0%, 1%), and ambient temperature (25℃, 100℃, 200℃, 400℃, 600℃) on the fracture properties of RPFC. In addition, digital image correlation (DIC) techniques were used to measure crack development in RPFC notched beams. The fracture patterns, micro-crack initiation and extension and macro-crack development in the fracture process were identified using acoustic emission (AE) techniques. The results show that incorporating rubber powder into polypropylene fiber concrete can delay the crack propagation process, improve the deformation ability and make the fracture path more tortuous. With the rubber powder content increase from 5% to 15%, the initiation fracture toughness of RPFC notched beam decreased, the unstable fracture toughness and the fracture energy increased. When the ambient temperature rises from 25 ℃ to 600 ℃, the fracture energy and fracture toughness of RPFC increases first and then decreases, the crack mouth opening displacement increases, and ductility increases significantly. AE analysis further shows that the growth rate of accumulate counts decrease significantly with the rubber powder content in RPFC, indicating the rate of damage development has slowed down in some extent.

Study on Performance of Retarded Composite Semi-Rigid Base Mixed with Rubber Powder.

In order to solve the problem of poor crack resistance and frost resistance of semi-rigid base, rubber powder and retarder were added to a semi-rigid base mixture. First, 61 mixing ratios were determined. Then, through the unconfined compressive strength, splitting strength, and other tests, the mechanical, crack, and frost resistance properties of the retarded composite semi-rigid base coarse mixture with rubber powder were studied. Finally, the macro and micro properties of the two kinds of admixture composite semi-rigid base coarse mixtures were studied by means of SEM and industrial CT. The results show that rubber powder and retarder can effectively improve the cracking and freezing resistance of the mixture. After five freeze–thaw cycle tests, the strength of the retarded composite semi-rigid base material mixed with rubber powder decreased slightly compared with the mixture without additives. It can be seen that rubber powder improved the frost resistance of the mixture. When the content of rubber powder was 1.5%, the BDR value of the mixture increased by 8.8%. With the increase of unconfined compressive strength, splitting strength, and flexural tensile strength at 28 d and 90 d, it was found that the retarder improved the middle and late strength of the mixture. When the content of retarder was 0.09%, the increase of unconfined compressive strength at 28 d reached 3.9%. The addition of rubber powder and retarder improved the distribution of internal pores, the proportion of large pores decreased, and the proportion of small pores increased. The retarder changed the morphology of hydration products, formed a dense network supporting structure, further refined the pores, and reduced the porosity of the mixture. The proportion of pores with a volume greater than 100 mm3 in the total pore volume decreased by 26.01%, and the proportion of medium pores increased by 13.07%, thereby improving the mechanical properties of the mixture.

Research on the dynamic impact performance of polyurethane cement-based composite

The polyurethane cement-based composite (PUCC) has excellent mechanical properties and deformability, which has broad application prospects in civil engineering. However, the research on dynamic impact properties of PUCC is limited. Therefore, in this paper, 11 groups of PUCC specimens were prepared by using different content of basalt aggregate (BA), rubber powder (RP), and polyethylene fiber (PE). Then, the Split Hopkinson Pressure Bar (SHPB) was used to study the dynamic impact tests on PUCC specimens. The stress–strain curves, dynamic stress, dynamic increase factor (DIF), and compressive toughness of PUCC specimens under various strain rates were obtained. The results show that the PUCC has excellent dynamic impact resistance, and its dynamic stress can reach 2 to 3 times of ordinary concrete. The dynamic mechanical properties of the specimens decreased significantly when the BA was added. The dynamic stress, DIF, and compressive toughness decreased by 25%, 13%, and 50%, respectively. Different from BA, the dynamic stress, DIF, and compressive toughness were increased when the PE was added. The incorporation of RP would slightly reduce the dynamic peak stress. However, the DIF and compression toughness were significantly improved. When the content of RP was 40 wt%, the dynamic stress was reduced by 2.5%, while DIF and compressive toughness are increased by 45.7% and 18.7% respectively.