Utilization of Sewan River Aggregate in Sarmi Regency as a Mixture for AC-WC

The rapid development of road infrastructure increases the need for materials to be used, including the use of aggregates. This study aims to examine the use of aggregate from the Sewan River in Sarmi Regency as an asphalt mixture. In this study by conducting several tests such as checking the characteristics of course (stone), fine (sand), filler and asphalt characteristics. After that, a mixture of asphalt composition (AC-WC) was made and then the Marshall test was carried out to obtain the properties of the mixture. The results of testing the composition of the AC-WC mixture obtained the composition of the mixture for the optimum asphalt content of 7.50%, coarse aggregate 36.75%, fine aggregate 50.00%, and filler 5.75%. This shows that the aggregate characteristics of the Sewan river for the AC-WC mixture with the conventional Marshall method that meet the 2018 General Specifications of Highways are stability (Asphalt content 4.00%-11.00%), Flow (Asphalt content 4.00%-11 0.00%), VIM (asphalt content 4.00%-7.50%), VMA (asphalt content 5.75%-11.00%) and VFB (asphalt content 5.75%-11.00%). As for the Marshall Immersion test, the remaining Marshall stability value is 95.15%.

Experimental Study on the Pavement Performance of Cement-Improved Silty Fine Sand

In view of the fact that there is in shortage of superior roadbed fillers in gobi and desert areas and based on the economical and environment-friendly concept, the cement-improved silty fine sand will be used as the roadbed filler of a railway construction project, which has the engineering characteristics of difficult compaction of local silty fine sands and loose structure, within the territory of Jiuquan, Gansu Province.The test indicated that the actual silty fine sands presented relatively concentrated particle sizes in this project, the particle composition was uniform and difficult to compact. The 7d saturated unconfined compressive strength of the cement-improved silty fine sand filler was correlated with the cement content, curing age and compaction coefficient, and also showed a good linear fitting relation with the cement content. As the delay time of sample molding was lengthened, the 7d saturated unconfined compressive strength of the samples was gradually reduced, and the strength retention rate had a favorable fitting relation with the delay time of sample molding. The compaction coefficient was detected using the sand-cone method in the field compaction test, and on this basis, the “ex post detection” method was proposed to detect the compaction coefficient of this special type of fillers.

Mortars Based on a Ternary Binder from Lime, Metakaolin and Calcium Hemihydrate

Normal-weight mortars with quartz sand filler and lightweight mortars with expanded perlite filler were prepared from a lime-metakaolin-gypsum binder. Mortar test samples were cured in a humid atmosphere and also in the laboratory ambient conditions. Development of hardening processes was studied by X-ray diffraction, thermal analysis and SEM-EDS observation. Compressive strength, drying shrinkage, bulk density and thermal conductivity of the mortars were determined. The presence of gypsum binder in the mixtures enabled formation of ettringite that caused expansion and reduced drying shrinkage of mortars with 20% content of gypsum binder.

Experimental study on the adsorption of dissolved heavy metals by nano-hydroxyapatite

Bioretention system is an effective way to solve the problem of urban water environment pollution. In this paper, the difficulty of the existing biological retention system to effectively remove dissolved heavy metals was studied. By comparing the adsorption effect of acid quartz sand filler layers with nano-hydroxyapatite (N-HAP), medical stone, nano-carbon, and biochar, the conclusion is drawn from the static and cylinder dynamic experiments that N-HAP has the best effect of removing Cu2+ and Zn2+, and the effect is long lasting. The scanning electron microscopy results showed that the N-HAP particles were rough and the surface was more rod-shaped, which increased the specific surface area of the N-HAP particles, promoted the complexation and electrostatic interaction of the additives and heavy metal solutions, and facilitated the adsorption of heavy metals. The research results help to improve the technology of filler matrix modification.

Physico-Mechanical Properties of Cellulose Fiber-Cement Mortars

This paper is aimed to investigate the total sand filler replacement by two types of cellulosic fibers (bleached wood pulp - WP and recycled fibers from waste paper - RF) in cement-based mortars. Two different types of cement mortar, one with addition of finely ground limestone and other with powdered granulated slag, were mixed with fibers. The changes in consistency of fresh fiber cement mortars and development of compressive and flexural strength of mortars in dependence on hardening time up to 90 days was studied. The development of compressive and flexural strength with increasing hardening time of cellulose fiber mortars and two binders with different properties confirmed that binder mixtures containing finely ground slag and recycled cellulose fibers achieved higher values of these strength parameters. Also adhesion testing of fiber cement mortars on two substrates (ceramic fitting and aerated concrete block) after 28 days of their application showed better adhesion of cement mortars with finely ground granulated slag on the ceramic fitting surface compared to the mortars containing finely ground limestone. However, any cracks have occurred on both substrates during the maturing of mortars with slag. Based on the above facts, it can be concluded that suitable plaster mixtures for their use in the interior appear the cement recipes with both cellulose fibers (wood pulp and fibers from recycled waste paper) and with finely ground limestone.