Recovery of Excavated Materials as an Alternative Solution to Earth Building Materials

The tunnel excavation works generate huge quantities of earth. These excavated materials are primarily stored in landfills. This paper proposes an alternative solution for valorizing excavated earth in earthen constructions. Firstly, the excavated earth was characterized using differential and gravimetric thermal analysis (DTA / TGA), infrared spectra (FTIR), and X-ray diffraction. Hence, sand, fine particles, and water extracted from excavated earth are used to elaborate mortars’ stabilized with cement, lime, and slag. Short hemp fibers were also used to diminish shrinkage cracks. The quantity of stabilizers was fixed to 5% by weight of the excavated earth while the water/solid ratio was maintained constant and equal to 0.45. Five different mortar formulations were performed using excavated earth and were cured for 28 days in a controlled environment before testing. Compressive and three-point flexural tests were carried out to determine specimens’ mechanical properties. The characterization results show that the excavated earth are mainly composed of dolomite, calcite, quartz, and clay. While, the mechanical results show that the stabilized excavated earth with cement additive presents higher mechanical properties relative to the other additives.

Freeze-Thaw Behavior of Stabilized Clayey Soil with Red Mud and Cement

The clayey soils in areas with seasonal frost are exposed to at least one freeze-thaw cycle every year and worsen their engineering properties. To prevent the engineering properties of clayey soils, it is necessary to improve the freeze-thaw resistance of them. In this study, the clayey soil was stabilized by using red mud and cement additive materials. Prepared samples of clayey soil and stabilized clayey soil were subjected to the unconfined compressive test. To investigate the effects of red mud and cement additive materials on the freeze-thaw resistance of clayey soil, the natural and stabilized expansive soil samples were exposed to the freeze-thaw cycles under laboratory conditions. The obtained results showed that the red mud and cement additive materials increased the freeze-thaw resistance of clayey soil. Consequently, it was concluded that red mud and cement additive materials can be successfully used to improve the freeze-thaw resistance of clayey soils.

Features of using cement suspension in concrete mixture recycling technology

Introduction. Recycling technologies may solve the problem of landfill waste. The problem of hydraulic active cement waste using not fully resolved in concrete mixtures recycling technologies. Using hydraulic active cement waste as an addition directly influences the technological and mechanical characteristics of new concrete mixtures. That requires additional research. Materials and methods. The cement waste obtained after recycling was simulated by pre-hydrated cement suspension produce at V/C equal to 0.7 for 6 hours of hydration. Different compositions of cement mixtures were investigated. The difference of which was amount of introduced pre-hydrated cement additive, both in the presence and without plasticizer. Technological properties, namely the normal consistency and setting time of cement compositions were investigated by standard methods of GOST 30744-2001. Mechanical properties, namely the compressive strength at the age of 28 days, were determined by destructive method on a hydraulic press PSU-10. Results. The introduction of a pre-hydrated suspension causes an increase in normal consistency, a reduction in the setting time and a decrease in strength with an increase in its quantity. The use of such a suspension in conjunction with a superplasticizer can level out the increase in normal density, as well as increase the strength of the samples. Timing of setting remained similar to the results of the test without the plasticizer. Conclusions. The results of the study show influences of cement waste obtained after recycling on the technological and mechanical characteristics of new mixtures. These influences are important and must be taken into account in the design of new concretes and mortars.

BETON BERMUTU DAN RAMAH LINGKUNGAN DENGAN MEMANFAATKAN LIMBAH ABU BAN BEKAS

The need for housing is increasing day by day. This is a factor in the visit to the need for concrete as a housing construction material. The more concrete that is produced, the more cement is needed for the construction. Concrete is a composite material (mixture) of several materials, the main ingredient of which consists of a mixture of cement, fine aggregate, coarse aggregate and water. Utilization of waste tire ash in the concrete mix is one of the alternative uses so that ic can ultimately increase the efficiency of cement savings which takes a long time to increase in high prices. With reference to this, this study uses used waste as a cement additive with a mixture composition of 0%, 3%, 6% and 9%. The test specimens were made using a cylinder with a diameter of 15 cm and a height of 40 cm with 48 specimens produced. The results of the compressive strength test of normal concrete (25.45 MPa), while the concrete with a mixture of 3% used tire ash (28.15 MPa), 6% used tire ash mixture (23.46 MPa) and 9% used tire ash mixture (18.60 MPa). From this research, it can be said that compressive strength of concrete using 3% ash produces the greatest compressive strength of 28.15 MPa.

PEMANFAATAN ABU KERTAS DAN SERBUK CANGKANG LOKAN PADA CAMPURAN BETON NORMAL DENGAN MENGGUNAKAN SIKACIM CONCRETE ADDITIVE

This research uses paper ash, lokan shell powder, and sikacim concrete additivefor normal concrete mix. Paper ash is used as a cement additive, while lokan shell powder is used as a partial substitute for sand. To overcome the lack of water in the concrete mixture, Sikacim concrete additive is used. The purpose of this study was to determine the compressive strength of concrete resulting from the use of paper ash as an additive and lokan shell powder as a substitute for sand by adding sikacim concrete additive.The test object used a cube mold of 15 cm x 15 cm x 15 cm with a concrete compressive strength of K-250 design at the age of 28 days of testing. Variations of the specimens used paper ash 0.25% by weight of cement, and lokan shell powder 0%, 10%, 20%, 30% by weight of sand, and 0.7% additive from the volume of water. Based on the results of the compressive strength test of concrete, the compressive strength of concrete is obtained, for normal concrete it is 276.6 kg/cm2, from the use of 0.25% paper ash, 0% lokan shell and 0.7% additive of 362.6 kg/cm2, from the use of 0.25% paper ash, 10% lokan shell and 0.7% additive of 365.3 kg/cm2, from the use of 0.25% paper ash, 20% lokan shell and 0.7% additive of 300.53 kg /cm2, from the use of 0.25% paper ash, 30% lokan shell and 0.7% additive of 250.16 kg/cm2.

WETTING AND DRYING CYCLES EFFECT ON DURABILITY OF GYPSUM SOILS TREATED WITH CALCIUM CHLORIDE OR CEMENT ADDITIVES

The study consists of two stages: the first one is to improve the gypsum soil with cement or calcium chloride and the second stage is to expose these soil specimens to series of wetting and drying cycles .Three soil specimens were taken and marked as (A,B and C) with gypsum content (47, 32 and 23)% respectively .The results show that cement additive increases the cohesion of soil specimens to 50% and collapse potential decreases with 65% and soil specimens improved with calcium chloride increase the cohesion up to more than 70% and collapse potential decreased about 70%. In the first cycle for wetting and drying cycles for soil specimens improved with cement the cohesion decreases about 25% and stays with the same ratio of the decreasing along the other cycle up to twelfth cycle. Collapse potential remains with the same value and is not affected by cycling of wetting and drying. In the first cycle for soil specimens treated with calcium chloride there is no effect in the first cycle whereas in the fourth cycle the cohesion increased by 60% and in the eighth cycle the cohesion decreased 8% and remains stable until the twelfth cycle. Collapse potential increases from one cycle to another by (30-50) % for all soil specimens.