Papers by Keyword: Unfired Brick

Abstract: Kaolin is one of the most vital industrial minerals whose application is reliant on its chemistry and structural makeup. This research attempts to determine the properties of unfired kaolinitic clay bricks for sustainable construction. Samples of the material were pre-treated and analyzed to obtain their physical and refractory properties, such as chemical composition, microstructure, moisture content, dry density, linear shrinkage, plastic index, and crushing strength. The results revealed that the clay comprises high percentages of silicon and alumina oxides being 75.6% and 17.0% of the total oxide composition respectively. The clay also contained some residual impurities in the form of metallic oxides i.e., oxides of iron, sodium, calcium, potassium, manganese, and lead. Characterization tests on the clay presented a specific gravity of 2.66, liquid limit of 38, plastic limit of 25.9, and plasticity index of 12.1 which classifies the clay as low-plasticity clay based on the Unified Soil Classification System. The river sand used was distributed between 0.06 – 3 mm falling within the category of medium and fine sand. The aggregate fineness modulus was obtained as 3.03%. The coefficient of uniformity was lower than 4.0 and thus classified as being uniformly graded. Stabilization of the clay with sand and lime resulted in decreased compression and flexural strength but increased durability. The results imply that kaolinitic clay can be used in an unfired form for earth construction.

Abstract: Al₂O₃-MgO unfired bricks were prepared by using brown corundum, white corundum, fused magnesia and α-A1₂O₃ micropowder as main starting materials, Al₂O₃-SiO₂ gel powder as a binder. The effects of magnesia fines addition on physical performance of Al₂O₃-MgO unfired bricks were investigated. The phase composition and microstructure were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). The results showed that with the increase of magnesia fines addition, bulk density of Al₂O₃-MgO unfired bricks after dried decreased and strength increased. After heat treatment at 1100 °C, apparent porosity (AP) slightly reduced, bulk density (BD) slightly increased. Strength had little change. After heat treatment at 1500 °C, AP first decreased and then increased, and strength change correspondingly. The hot modulus of rupture (HMOR) first increased and then decreased with increasing magnesia content. The optimum magnesia addition is at 6.0 wt. %.

Abstract: Despite their low performance quality and aesthetics, non-standard bricks are commonly used in the construction of low-rise buildings and rural houses in Indonesia. These bricks are produced traditionnally in home run plants with little adherance to appropriate mix designs. These unfired soil lime bricks enter the market within 2 weeks of production, which inflicts potential loss to the buyers due to their low performance quality. The paper discusses strength improvements of these early age bricks through 2 methods. The first method is by adding the optimal amount of mixing water to the soil and lime mix. The second method is by adding untreated coconut fibers with a 2.5 cm fiber length as additional reinforcements. The effect of 3%, 5% and 7% fiber addition to the mechanical properties of bricks were investigated. Laboratory tests showed that higher compressive strengths, compared to that of traditional unfired soil lime bricks, could be achieved through the 2 proposed methods. The bricks reinforced with higher percentage of untreated coconut fibers have better modulus of ruptures.

Abstract: A new environment-friendly wall material- the unfired brick is produced by using clay, carbide slag, fly ash and cement as the main raw materials，and certain amount of chemical excitator. The primary mixing ratio is designed on the basis of its mechanical properties and durability. When adopting water curing under normal temperature and atmosphere pressure，the compressive strength，flexural strength and frost resistance of the unfired brick are measured. The results reveal that the optimum mixing ratio for unfired brick is: Carbide slag 30%，fly ash 30%，cement 25% and clay 15%. For the unfired brick formed by vibration with the optimum mixing ratio，the min. compressive strength of each brick is more than 10 MPa, the overall properties meet the requirement as specified in standard JC 239—2001“Fly Ash Brick”.