Series Of Compressive Strength Tests Research Articles

Utilization of Plastic Waste Material in Masonry Bricks Production Towards Strength, Durability and Environmental Sustainability

The level of generated plastic waste has awash over a billion metric tonnes of this waste into our environment. If an effective long-lasting solution to this impending disaster is not provided through recycling, reengineering, and conversion of this waste to resourceful materials. Then sustainability and conservation of natural non-replenishable materials will be severely threatened. The aims to avert the impending consequences of this disaster and conserve natural materials have given rise to a sustainable future in the production of low carbon embedded construction materials. Under these circumstances, this study, therefore, presents the strengths and durability of waste plastic bricks (WPB) produced from blending scrap PET plastics and foundry sand. The WPB masonry bricks were produced using ratios of 10:90, 20: 80, and 30: 70 to the combined dry mass of PET and sand. Series of compressive strength tests, modulus of rupture (MOR) tests, apparent porosity tests, water absorption tests, salt-resistance tests, ultrasonic pulse velocity, and scanning electron microscopy (SEM) tests were conducted to investigate the strength and durability of the WPB in conformance with the South African National Standard (SANS 227) for individual load-bearing masonry face brick unit. Compared to the clay bricks with 18 MPa what of strength, the test result revealed that the WPB rendered an average compressive strength of 35.2 MPa. Furthermore, the test result showed that the WPB recorded significant strength resistance under tension compared to the clay brick due to the ductility properties of scrap plastic waste. Also, the acid effects were significantly resisted on the surface WPBs due to the hydrophobic property of the PET- waste. The stiffness of the clay bricks portrayed brittle response, whereas WPBs benefited with high ductility properties, therefore, revealed a great proportionality between the dynamic modulus and ultrasonic pulse velocity (UPV) with a coefficient of determination (R2) of 90%.

Experimental and numerical analyses of lightweight foamed concrete as filler for widening embankment

In order to control the differential settlement between the existing and widened embankments, lightweight foamed concrete (LWFC) was proposed as a filler of the widened embankment to decrease its self-weight. A series of compressive strength tests, dynamic triaxial tests, dry–wet cycle tests, and water immersion tests were performed to analyze the variation of the LWFC strength with design dry density and the influence of water and adding glass fiber (GF) on the properties of the LWFC. Then two centrifugal models of the widened embankment, which was filled with the LWFC and traditional soil respectively, and their numerical models were established in this study. The results show that water adversely affects the LWFC strength. A lower density for LWFC is corresponded by greater compressive strength loss after the LWFC underwent 15 dry–wet cycles. When the LWFC with a design dry density of 300–800 kg/m3 was immersed in dead water, the compressive strength and dynamic stress threshold ratios of the LWFC decrease quickly at first and then increases slightly with increasing soaking days. While the LWFC was immersed in live water, these parameters gradually stabilize for a design dry density of no less than 600 kg/m3 and decrease for a design dry density of less than 500 kg/m3 with increasing soaking days. Mixing GF into the LWFC can significantly improve the compressive strength and dynamic stress threshold and reduce the influence of water. Furthermore, the use of the LWFC as a filler of the widened embankment can significantly decrease the settlement of the embankment surface, soil pressure on the foundation surface, and horizontal deformation of the foundation compared to the traditional soil used as filler for widening embankment.

Development of new pH-adjusted fluorogypsum-cement-fly ash blends: Preliminary investigation of strength and durability properties

This paper develops a new low-cost construction material made of pH-adjusted fluorogypsum, class C fly ash, and type II Portland cement. The proposed fluorogypsum-based blend is durable in water and has a lower weight and lower cost than ordinary concrete. A preliminary investigation of strength and durability properties of this new construction material is also presented. A series of compressive strength tests and volumetric expansion measurements were conducted on specimens after 28 days of curing. The experimental results were used to develop response surface models. These models can be used to predict accurately compressive strength and volumetric expansion as functions of the relative content, in dry weight, of different components. The response surface models were employed to determine ranges of dry components of the system with sufficient strength and limited volumetric expansion. A composition with 62% pH-adjusted fluorogypsum, 35% fly ash, and 3% Portland cement was selected based on strength and volumetric expansion properties to conduct additional experimental studies to quantify its modulus of elasticity, Poisson’s ratio, setting times, density, void contents, and curing time effects on strength and volumetric expansion. The investigation results suggest that the proposed fluorogypsum-based blend is a promising low-cost concrete-like material for use in outdoor and underwater construction applications.

Modelling of the compressive strength development of cement mortar with furnace slag and desulfurization slag from the early strength

Replacing natural resources with renewable materials is a very important research topic for sustainable development. Several recycled materials such as furnace slag (S) and desulfurization slag (D) were widely used and applied in concrete or cement mortar. The compressive strength at the 28th day was usually used as design strength for structure. Thus, an assessment of the compressive strength of cement mortar with furnace slag and desulfurization slag from the early strength is desirable to develop. In this study, desulfurization slag that could pass through a No. 4 sieve and furnace slag with a fineness of approximately 4000cm2/g were used to replace the fine aggregate (0%, 10%, 20% or 40%) and cement (0%, 10%, 20% or 40%), respectively, through a volumetric method. The cement mortar thus formulated was then put through a series of compressive strength tests in which the samples were cured at a 23–25°C room temperature and a 75°C high temperature. According to the test results, the compressive strength decreased as the replacement rate of desulfurization slag increased, but increased as that of the furnace slag increased. Using the test results when the replacement rates of D were 0%, 10% and 20%, a hyperbolic function was used to perform a multivariate non-linear regression analysis, thus establishing a compressive strength prediction model for cement mortars of other ages based on the early strength at the age of 7days. From the confirmatory analysis, when the replacement rate of desulfurization slag D=40%, the MAPE (mean absolute percentage error) value of the test sample cured at high temperature was found to be 6.13%, while that for the test sample cured at room temperature was 11.32%. Moreover, when D was 0%, 10% and 20%, the MAPE value for the test sample cured at high temperature was 3.05%–4.47%, respectively, while that for the test sample cured at room temperature was 7.83%–9.17%. Generally speaking, the results delivered by the analytical model established in this study were satisfactory under different conditions. As it is capable of performing a predictive analysis of the compressive strength of cement mortar at other ages based on the early strength at the age of 7days, this model could contribute to the safety assessment of concrete structures during the construction phase.

Controlled tropical curing method for accelerated concrete strengths

Accelerated curing and testing of concrete can be used for both quality control and quality assurance. This paper presents controlled curing and accelerated curing methods for early assessment and prediction of strength of concrete and discusses their relative merits. The controlled curing method utilises the inherent high ambient temperature of the tropics without the artificial heating needed for other accelerated curing methods. The test specimens are controlled cured for only 24 hours prior to testing.A series of compressive strength tests were conducted on concrete of varying proportions. Two types of water reducing admixtures were used individually in some mixes. A multiple linear regression technique has been adopted where appropriate to correlate the 28-day standard cured strength with the controlled cured strength, 35° cured strength, 55° cured strength and standard 2 day and 3 day strengths. The correlation results are discussed in detail. The important observations arising in this study are: the simplicity of the controlled curing method; the reliability of multiple linear regression relations; and the small effect of admixtures on the correlations between strengths.

Controlled tropical curing method for accelerated concrete strengths

Accelerated curing and testing of concrete can be used for both quality control and quality assurance. This paper presents controlled curing and accelerated curing methods for early assessment and prediction of strength of concrete and discusses their relative merits. The controlled curing method utilises the inherent high ambient temperature of the tropics without the artificial heating needed for other accelerated curing methods. The test specimens are controlled cured for only 24 hours prior to testing. A series of compressive strength tests were conducted on concrete of varying proportions. Two types of water reducing admixtures were used individually in some mixes. A multiple linear regression technique has been adopted where appropriate to correlate the 28-day standard cured strength with the controlled cured strength, 35° cured strength, 55° cured strength and standard 2 day and 3 day strengths. The correlation results are discussed in detail. The important observations arising in this study are: the simplicity of the controlled curing method; the reliability of multiple linear regression relations; and the small effect of admixtures on the correlations between strengths.

Some preliminary test data on cement–pfa–anhydrite mixes

Synopsis Cement-stabilized pfa is commonly used as a load-bearing fill for civil engineering purposes. Anhydrite is often used for similar purposes in the mining industry. A series of compressive strength tests were carried out on combinations of these three materials to determine their potential as moderate to high-strength fills. The tests were carried out on 38mm dia. by 75mm long specimens prepared by static compaction techniques. Attempts to stabilize pfa using anhydrite showed little potential for increasing the load-bearing capacity of pfa. However, a study of the combination of cement and anhydrite in the stabilization of pfa showed these two materials to be complementary in increasing the compressive strength of compacted stabilized pfa compared with using just cement or just anhydrite as the stabilizing agent. The 14, 28 and 56 day strengths of cement-bound pfa were more than doubled by the replacement of 1·4% cement by weight with 10% anhydrite by weight. The addition of higher proportions of anhydrite could decrease this enhanced strength or give only a marginal increase. Long-term tests after a curing period of one year showed no apparent deterioration in strength.