Porous poly(urethane urea) microparticles for immobilization of maltogenic α amylase from Bacillus stearothermophilus

Maltogenic α amylase from Bacillus stearothermophilus (BsMa) was immobilized by covalent attachment and physical adsorption onto porous poly(urethane urea) (PUU) microparticles obtained from poly(vinyl alcohol) (PVA) and 4,4’-methylenebis(cyclohexyl diisocyanate) (H12DI) by onepot synthesis. The influence of PUU synthesis parameters such as PVA and H12DI molar ratio, synthesis time and temperature on porosity, surface area, structure of microparticles and catalytic activity and stability of immobilized BsMa was investigated. The highest efficiency of the immobilization of BsMa onto the PUU carrier was 97% and the highest residual stability of the immobilized enzyme reached 95% after 28 days of storage at 4°C. The optimal activity temperature of immobilized BsMa was at 80°C and it was higher than that of native enzyme. Effects of ionic strength and repetitive batch processing cycles on the activity of immobilized BsMa were also studied. Immobilization of BsMa onto PUU carriers has a great potential for biotechnology and food industries.

Characteristics of AC-WC Mixture Using Waste Tires Added Material

The problem of the quality of the asphalt mixture, especially on the surface layer, is a matter that really needs to be considered because a poor asphalt mixture will cause the surface layer on the road to be damaged quickly or not in accordance with the expected service period. This research was conducted to test the AC-WC mixture with added waste tires. The research methodology uses the Conventional Marshall method to obtain the characteristics of the AC-WC mixture and Marshall Immersion to obtain the Marshall Residual Stability value. The results show that the characteristics of the AC-WC mixture meet the 2018 Highways Specifications. The results of the Marshall Immersion test with an optimum 4% used tire content obtained a Marshall Stability value of 94.64% and the effect of adding used tire rubber will make the cavities in the mixture smaller thus the mixture can be resistant to water.

Research on Road Performance of Asphalt Mixture With Iron Waste Ore

In order to study the road performance of asphalt mixture with different kinds of iron waste ore , stripping waste rock rich in iron trioxide and stripping waste rock rich in iron oxide are used as aggregate to make the mixture.Through the test comparison, it is confirmed that the dynamic stability performance of asphalt concrete mixture mixed with iron trioxide mining and stripping waste rock is the best, namely its high temperature stability is best; followed by the one mixed with waste rock rich in iron trioxide. The residue stability of asphalt concrete mixed with mining and stripping waste rock increases obviously. It can found from the experiments that the residual stability can be up to 94.96% which kinds of asphalt mixture with waste rock rich in iron trioxide. Asphalt mixture mixed with stripping waste rock has a better anti-sliding performance than the common one, among which the one mixed with aggregates rich in iron trioxide is the best. Through tectonic depth, it is reflected that it also has a better performance on drainage noise reduction. In conclusion, using mining and stripping waste rock instead of mining gravel has a good economic efficiency,but also solved the problem of mining and stripping waste rock accumulation.

Study on water stability of asphalt binder with medium weathered igneous rock

Aiming at the problems of weak acidity of medium weathered igneous rock around Nairobi, Kenya, poor adhesion with asphalt and poor water stability of asphalt binder, the article studied the use of anti-stripping agent, cement, hydrated Lime and other technical measures to improve the water stability of asphalt binder with medium weathered igneous rock. The results showed that the 48h Marshall residual stability of the benchmark asphalt binder without any measures was 78.5%, which did not meet the standard requirements. The Marshall residual stability of medium weathered igneous rock can be significantly improved by adding anti stripping agent, cement and hydrated Lime. After freeze-thaw cycles, the splitting tensile strength of the asphalt binder with medium weathered igneous rock decreased obviously, and the TSR values of the asphalt binder with anti-spalling measures from small to large were K-4, K-3, K-2, K-6 and K-5. The water stability of the medium weathered igneous rock asphalt binder mixed with anti-stripping agent alone had relatively poor durability, and the medium weathered igneous rock asphalt binder mixed with cement and anti-stripping agent had the strongest ability to resist deformation when immersed in water.

Development and Evaluation of Solvent-Based Cold Patching Asphalt Mixture Based on Multiscale

In order to prepare a kind of high-performance asphalt pavement pit repair material and extend the service life of the road, this paper starts from the microscopic view of the raw materials, uses infrared spectrum, four component analysis method, lying drop method, column wick technology principle, etc. to select the raw materials and determine the initial amount of the cold patching asphalt mixture, and optimizes the formula through the orthogonal test design and adhesion, cohesion, initial stage strength, later strength, residual stability, and other performance indexes, and determines the final formula of cold patching asphalt mixture as follows: the design porosity is 15 ± 0.5%, compatibilizer is 2.5%, linear SBS modifier is 5%, tackifier is 4%, antistripping agent is 3.5%, and the dosage of diluent D should be determined according to the ambient temperature. The results show that the performance of the self-made cold patching asphalt mixture is good verified by adhesion grade, strength, high temperature stability, water stability, and other road performance.

Preparation and Performance Evaluation of Cold Mix Asphalt Mixture

Cold mix asphalt mixture has a low strength and poor water stability, hence to solve this challenge, a cold mix asphaltic liquid was prepared in this study based on microscopic properties. LB-10 gradation was adopted and basalt fiber was selected as a reinforcing agent. The optimum asphaltaggregate ratio was determined by the Marshall test, and mix proportion was also designed. The laboratory tests were used to systematically evaluate road performance of the cold mix asphalt mixture. From the test results, it was shown that the initial strength, molding strength, immersion Marshall strength, residual stability, freeze-thaw splitting ratio, residual rate and dynamic stability of self-made cold mix asphalt mixture were 2.42 kN, 4.87 kN, 6.79 kN, 92.8%, 82.05%, 99.5% and 632 times/mm respectively. The initial strength, molding strength and residual stability of mixture became 90.9%, 88.7%, and 96.2%, respectively of their former values after one-month storage, showing good workability. By analyzing its research data and comparing with its existing products, the developed cold mix asphalt mixture can not only meet the requirements for road performances of the cold mix asphalt mixture in terms of strength, workability and high temperature stability, but greatly improves the water stability, storage stability and cohesive performance of the mixture.

Effects of Aggregate Abrasrion Values to Marshall Properties of Asphalt Concrete AC- WC

Asphalt Concrete AC-WC is one of the most common pavement types used in Indonesia, consisting of a mixture of hard asphalt, filler and a continuous graded aggregate, which is mixed, pave and compacted at a certain temperature. The mixture of ashpalt concrete requires a mixing process that uses materials as the specifications. Aggregate abrasion becomes an important part that will be examined based on aggregate hardness each of quarry. Source of material are from Selayang, Sibiru-biru and Armed. Reference for properties value that use in this study is specification from Public Works Department in 2005. From the Experimental, abrasion of material from Selayang 13.51%, Sibiru-biru 17.08% and Armed 35.64%. Optimum Asphalt content was 5.2%, 5.7% and 6.2%. From the research, the results of abrasion testing in this study, the coarse aggregate derived from the three quarry can be used as an aggregate mixture on (AC-WC), with abrasion value < 40%, and mixed properties (stability, flow, VMA , VIM, VFA, MQ) meet the standard specifications of the Department of Public Works April 2005. Increase value of abrasion will decrease performance of asphalt concrete. One of indicator is stability value, in this study the maximum stability value is 1005.31 kg at abrasion value of 13.51%. Increase value of abrasion also decrease the durability, maximum residual stability is 915.73 kg and durability is 91.09%.

Comprehensive Evaluation of Asphalt-Mixture Performance Based on Principal Component Analysis

Making the test specimen of asphalt mixture, testing the parameters of specimen, such as bulk specific gravity, percentage of voids in aggregate, percent bitumen volume in asphalt mixtures, asphalt saturation,percent voids in coarse mineral aggregate, marshall stability, dynamic stability, marshall residual stability ratio, freeze-thaw splitting strength ratio. Based on the method of principal component analysis, the items of principal component and the contribution rate will be calculated. With the cumulative contribution rate of 90% for the standard, the principal components will be selected. Taking the contribution rate as the weighting, the comprehensive score will be calculated. The research shows that using the method of principal component analysis to comprehensively evaluate asphalt-mixture performance is workable.