COMBINED INFLUENCE OF GRAVEL AND CRUSHED BURNT BRICKS ON THE PROPERTIES OF CONCRETE

The quest for alternative materials in concrete production is ongoing as the demand for concrete using conventional material increases. This study investigates the properties of concrete produced with Crushed Burnt Bricks (CBB) as replacement for Unwashed Gravel (UG). Concrete mixes of 1:2:4 (cement, sand and gravel) mix ratio were produced using UG/CBB combination in varying proportion of 100:0, 75:25, 50:50, 25:75, 0:100 which were represented as sample A, B, C, D and E. The water-to-binder (w/b) ratio of 0.4, 0.5, 0.55 and 0.6 were used for each sample. Sample A without CBB (i.e. 100% UG) served as control. Slump test was carried out on the fresh concrete while compressive strength test was carried out on the hardened concrete specimens using 150 mm cubes at the curing in ages of 7, 14 and 28 days, respectively. The slump values of fresh concrete increases with increase in w/b and CBB contents. At 28 days, the compressive strength values were 26.7 N/mm2 for concrete produced with sample B at w/b of 0.4 and 28.2 N/mm2 for concrete produced with sample A (control). It was concluded that the optimum level of substitution of 25% CBB for gravel is viable for concrete production from a structural point of view

A Response Surface Approach for Determining Optimal Mix Parameters for Normal Strength Concrete

The study evaluates the influence of water/ cement ratios and aggregates contents on the engineering properties of normal weight concrete. Response Surface Methodology (RSM) using historical design was adopted to design and develop predictive models and perform the optimization of concrete prepared with cement, fine aggregate (FA), coarse aggregate (CA) contents at different water/ cement ratio f0Q /C) by volume. Concrete mixes were prepared using fixed content of ordinary Portland cement and the different mixtures. The density and compressive strength of hardened concrete specimens were determined at the curing 28 days. The response surface analysis showed that W / C and aggregate contents have significant effects on density and compressive strength of concrete. The regression model yielded good correlations with the experimental data. The optimized density and 28-day compressive strength values of 2522.973 kg/m3 and 29.977 N/mm2 were achieved for the concrete mix containing 1.5-part ofF A, 3-part of CA and 0.60 W /C, respectively. The optimal concrete mix parameters determined using RSM provides the basis for selecting appropriate safe concrete component ratios

Strength Characteristics of M40 Grade Concrete using Waste PET as Replacement for Sand

The wide variety of industrial and domestic applications of plastic products has fuelled a global trend in their use. The vast amount of plastic items that are discarded after use, on the other hand, pollutes the environment. In light of this, the current study  investigated the use of Polyethylene Terephthalate (PET) as substitute for natural sand in concrete production. Locally sourced river sand was replaced with industrially ground waste PET in proportions of 4 to 20% at a step of 4% by the weight of natural sand whereas other concrete constituents (cement, granite, water-cement ratio and superplasticizer) were kept constant. A Grade M40 concrete with a mix proportion of 1:1:2:0.35 (cement: sand: granite: water-to-cement ratio) was used for all concrete mixes.  Concrete without PET represents the control. Fresh (Slump) and hardened (compressive, split tensile and flexural) properties of the produced concrete were assessed using standard testing methods. The results showed that the slump of concrete decreased by 1.8% and 12.5% with an increase in PET content from 0 to 20%. The 28-day compressive strength of concrete containing PET was lower than the control. However, concrete with 4% PET compared considerably well with control with the compressive strength value exceeding the target strength of 40 N/mm2 while concretes containing PET beyond 4% had compressive strength below the target strength. The split tensile strength of concrete containing 4% PET was higher than that of the control but exhibited lower flexural strength than the control at the age of 28 days. It was concluded that the reuse of PET as a substitute for natural sand as an alternative waste disposal solution for eco-friendly concrete development and attainment of a pollution-free environment is viable

Potential use of biomass ash as a sustainable alternative for fly ash in concrete production: A review

The broad utilization of concrete results in significant carbon dioxide emissions (CO2) and depletion of natural resources due to substantial increase in cement production. Fly ash, the waste product of coal combustion, has been used extensively as a cementitious additive in concrete to reduce the impact of cement production on the environment and also conserve the natural resources. However, the shortage in the supply of coal resulting from and stringent environmental regulations has led to a decline in fly ash production. Organic materials which are derived from plants and animals are regarded as biomass and the byproduct of biomass combustion are known as biomass ash. Several materials including biomass ash have been proposed as a sustainable alternative to fly ash in the production of concrete. Biomass ash as a supplementary cementitious material have been found to offer more advantages to traditional mineral additives improve the characteristics of concrete, decrease its environmental impact, and. In contrast, the use of biomass ash as mineral additives in concrete is largely unexplored in most developing countries, including Nigeria. This could be related to a lack of understanding of the region's biomass ash potential for such applications. The quality of concrete containing biomass ash can be greatly improved depending on the method used for its treatment, which is expected to increase interest in its use in the construction industry. Thus, there is the need for improvement in the quality of biomass ash to achieve high level of its incorporation for enhanced characteristics of cement mortar and concrete