Experimental assessments of methanol-based foaming agent in latex modified foamed binders and warm asphalt mixtures

Latex is one of the natural rubbers that is used to enhance the performance of asphalt pavement for the last few decades.The presence of latex,which is categorized as an elastomer,helps to improve pavement performance and durability.Conversely,higher viscosity of latex modified asphalt binder increases the production-temperatures of asphalt mixture,thus consuming higher energy during asphalt mixture’s production stage.In this study,the effectiveness of methanol as an energy-efficient foaming agent was assessed to reduce the viscosity and enhance the workability of the modified asphalt binder.The basic and rheological properties of the asphalt binders were determined through multiple laboratory tests including expansion ratio and half-life,rotational viscosity,softening point,torsional recovery,and dynamic shear rheometer.The properties of asphalt mixtures were assessed through the service characteristics,mechanical performance,and moisture resistance criteria.It was found that the presence of latex results in an approximately twofold higher expansion ratio and a lower half-life of the asphalt binder at about the same ratio.Through the rotational viscosity test,the application of methanol into asphalt binder decreased the viscosity and led to better workability,despite the addition of latex as an asphalt modifier.The application of methanol into asphalt binder improved the workability of mixture samples and lowered the compaction energy of the compaction process,which are the crucial criteria for a better mixing and compaction process.Methanol foamed asphalt mixtures with latex show much higher resistance to moisture damage and stiffness than control sample even though they were prepared at a lower temperature.

Effect of foaming agent,foam stabilizer and whipping time on drying process of tomato paste under different drying equipment

Laboratory experiments were conducted to determine the effect of foaming agent(egg white(EW)),foam stabilizer(carboxyl methyl cellulose(CMC))and whipping time on drying rate and quality of tomato(Lycopersicon esculentus)paste dried under air oven,microwave oven and mechanical dryer.A 43 factorial experiment in Randomized Complete Block Design(RCBD)was used to study the effect of four levels each of foaming agent(5%,10%,15%and 20%EW),foam stabilizer(0.15%,0.30%,0.45%and 0.60%CMC)and whipping time(3,5,7 and 9 min)on the drying rate and the quality of foam-mat dried tomato powder in the three drying equipment.Each trial was performed in triplicates making a total number of 576 samples that were individually tested and measured.25 g sample of the paste was dried to a moisture content of 7.60%(wb)for 8 h in mechanical dryer and oven dryer at temperatures of 55◦C and 50◦C,respectively,and 10 min in microwave oven at 540 W.Data obtained from the experiments were statistically analyzed using the analysis of variance(ANOVA)while the Duncan’s Multiple Range Test was used to compare the means.Results showed that the drying rate increased with increase in foaming agent,foam stabilizer and whipping with minimum values of 9.21 g/h obtained in mechanical dryer,9.31 g/h in air oven and 8.05 g/h in microwave oven.Increase in foaming agent,foam stabilizer and whipping time did not cause any adverse effect on vitamin C,ash,protein,fat,carbohydrate,crude fiber contents of the samples.Samples reached a stable moisture content of 7.60%(wb)in less than 8 h in mechanical dryer and air and less than 10 min in microwave oven.The results of the study showed that EW,CMC and whipping time influenced the drying rate and quality of foam-mat dried tomato powder.

Preparation of Controllable Cross-Linking Polyethylene Foaming Materials and Their Properties

In order to prepare the polyethylene materials with controlling properties,we developed two kinds of controllable cross-linking polyethylene foaming system.2,5-dimethyl-2,5-bis (tert-butyl peroxy) hexane was used as cross-linking agent and TEMPO as cross-linking inhibitor,azodicarbonamide (AC) was used as foaming agent and citric acid as foaming promoter.The density,expansion ratio,cellular structure and mechanical property of these two kinds of controllable materials were studied.Experimental results show that,properties of these two kinds of materials appear similar trend:cellular size and expansion ratio are enlarged with the amount of cross-linking inhibitor or foaming promoter increasing,while density and mechanical strength appear decreasing trend.Through comparing those two material systems’ properties,cross-linking polyethelene foaming system with citric acid as foaming promoter has better properties.

Models for Predicting the Jet Trajectory and Intensity Drop Point of Fire Monitors

Two models are defined for predicting the trajectory of a foam jet originating from a fire monitor(hydrant)and the related intensity drop point.An experimental framework is also defined and used accordingly to compare real-time data with the predictions of such models.This mixed theoretical-experimental approach is proven to be effective for the determination of otherwise unknown coefficients which take into account several important factors such as the operation pressure,the elevation angle and the nozzle diameter.It is shown that the mean absolute error is smaller than 20%.