Optimization of Preparation of Foamed Concrete Based on Orthogonal Experiment and Range Analysis

For the purpose of reducing the energy consumption and construction cost of buildings, the preparation process of geopolymer based foamed concrete, which is a novel material of the wall and roof of building, had been studied in detail. Water glass and sodium hydroxide were used as the alkali activator to excite the mixture consists of slag, fly ash and Kaolin to form the geopolymer matrix, and finally the foams generated using the physical foaming method were filled into the geopolymer matrix to produce geopolymer-based foamed concrete blocks. In the preparation process, firstly one of the four parameters of foam content, water-binder ratio, water glass content, and water glass modulus had been changed separately to study the influence of a single factor on the compressive strength, dry density, thermal conductivity and specific strength of foamed concrete blocks. The experimental results show that the above four factors have different degrees of influence on the concerned performances. Next, some representative combinations of these factors were constructed by orthogonal experiment method, and the influence degree of each combination on the concerned performances was determined by means of range analysis. According to the results of analysis, the most important influencing factor in terms of thermal conductivity was the water-binder ratio, followed by foam content, water glass modulus and water glass content. When the foam content is 1.58%, the water-binder ratio is 0.45, the water glass content is 30%, and the water glass modulus is 1.2, the thermal conductivity of the prepared geopolymer foam concrete reaches 0.044 W/(m·K), which satisfies the expected requirements for heating in severe cold areas.

Use of polyethylene terephthalate as an Anti-stripping agent in GLASSPHALT

This study evaluates the use of polyethylene terephthalate (PET) in Glassphalt aimed at increased bonding effect of bitumen, reduced stripping and increased in stability and strength. Control mix were prepared with bitumen content of 5.0, 5.5, 6, 6.5 and 7% to determine the optimum bitumen content (OBC). Optimum glass content (OGC) was obtained from samples prepared with glass content of 5, 10, 15, 20, and 25% replacement by weight of fine aggregates. The OBC and OGC were used prepare samples with PET content of 2, 4, 6, 8, and 10% by weight of the OBC. The optimum PET content had a higher stability value of 5.8kN and higher air void of 3.8% when compared to the control mix. Stripping value tests showed that PET modified glassphalt had 0% stripping after a period of 48 hours. Waste PET of 6.6% in 16% glassphalt is recommended for use as an anti-stripping agent.

INFLUENCE OF WOOD SAW DUST AND WASTE GLASS ADMIXTURE ON SELECTED PROPERTIES OF FIRED CLAY BRICKS FOR MASONRY

This study investigated the effect of mahogany wood sawdust (WSD) and waste glass (WG) addition on the properties and cost of producing fired clay bricks for construction of houses. Materials used were clay, WSD and WG. Brick samples were produced in batches and labeled as samples A (with no additives), B, C, D, E, F, G and H. Each sample of B, C, D, E, F, G and H contained 5% fixed amount of WSD, and 10, 15, 20, 25, 30, 35 and 40% of WG respectively. Brick samples produced were tested for apparent porosity, bulk density, compressive and flexural strengths, thermal conductivity and wear. Results obtained showed that as waste glass content increased in the samples, bulk density and compressive strength increased due to enhancement of densification and compaction within the samples. Thermal conductivity also increased as waste glass increased due to reduction in porosity and reduced inter-particle distance. The value of flexural strength increased with WG content but at 35% and 40%, the value reduced. This is as a result of an increase in brittleness as waste glass content increased which increased stress concentration in the samples, hence leading to a reduction in flexural strength. Also, it was observed that the increase in the content of the waste glass led to a reduction in the value of apparent porosity and wear depth due to improved cohesion between particles in the bricks. Comparing results obtained with existing standards and considering the cost of production, 5% WSD and 25% WG addition, with apparent porosity of 26.3%, compressive strength of 17.5 MPa, thermal conductivity of 0.32 W/mk and wear depth of 1.72 mm is recommended for construction purposes.

EFFECT OF MIX PROPORTIONS ON THE PROPERTIES OF CLSM CONTAINING RECYCLED GLASS

This research examined the effect of mix proportions namely, water to cementitious (w/c) ratio and glass content, on the flowability and compressive strength of controlled low-strength (CLSM) mixtures. A total of 20 mixes containing different proportions of cement, sand, class C fly ash, coarser glass, finer glass and water were prepared and tested. Results showed that both flowability and strength are dependent on w/c ratio and type and percent of glass content. Strength of mixes containing high volume of coarser glass was found more sensitive towards w/c ratio. Further strength was found to improve with increase in finer portion of the glass powder. Density was also found to correlate well with the moisture content of CLSM specimens. Specimens with lower moisture content produced denser CLSM structure. The results of this study would be useful in establishing mix proportions for CLSM incorporating recycled glass, fly ash, sand and cement for commercial applications

Recovery of Stabilizer Glass in Innovative MBT Installation—An Analasys of New Technological Procedure

The data published by the European Container Glass Federation shows that the EU28 average collection rate for recycling of glass containers has grown to a rate of 76%. However the stabilizer produced at mechanical-biological treatment (MBT) installations at landfills still contains large amounts of recyclable glass. An industrial-scale study has been undertaken in order to assess the possibility of recovering this glass from the stabilizer. A new pilot installation was built at the MBT plant in Marszów, Poland. Tests were conducted on stabilizer samples produced at the plant (13 samples) and others collected from several MBT plants based in Poland (six samples). Processing the stabilizer on the designed line made it possible to recover on average 68.4 ± 7.0% of the glass contained in it from Marszów samples and 58.4 ± 14.2% in the case of samples acquired from other MBT installations. It is demonstrated that the concentrate quality largely depends on the stabilizer’s moisture content. A concentrate with glass content from 98.0% to 99.5% was obtained for samples of low-moisture stabilizers (for 14 out of 19 samples). The product was accepted by glass recycling plants due to its low level of contamination with other materials and its appropriate particle size.