Concrete Demolition Research Articles

Time Optimization Analysis Of Drainage Projects (Case Study: Surya Indah II Complex Drainage Construction)

The rapid development of the world of construction means that competition in the construction services business must be able to compete. Therefore, careful consideration is required to choose a method so that a construction project can run effectively and efficiently with results that meet the objectives, one of which is the Surya Indah II Complex Drainage Construction. In a development project, considerable processing is required, taking into account the increasing size of the project and the complexity of the dependencies between one part of the work and another in a project to achieve the desired results. Proper scheduling along with adequate resource allocation contributes to project success. This is comparable to the Surya Indah II Complex Drainage Development Project in Banjarbaru City, which has a contract value of 1,480,920,041 billion. This project was supposed to be completed in 180 calendar days; however, it was delayed due to a variety of issues, including bad weather, a shortage of labor, and tardy mobilization. According to the data analyzed in this study, the CPM (critical path method) approach has a critical route. The total project period using the CPM approach is 170 days, calculated based on the longest critical route. Work networks studied using the critical path include mobilization work, tree trunk cutting, concrete demolition, asphalt cutting, box culverts, and other tasks. Using the CPM approach, you can cut the job duration by 2.8% of the contract value. The solution to speed up the duration obtained using the CPM method is to add workers, add productivity tools, add working hours to activities that are on the critical path, and add the Earned Value method for optimal results.

Investigation of Physical-Mechanical Properties and Microstructure of Mortars with Perlite and Thermal-Treated Materials.

This study aimed to obtain and characterize a mortar with perlite aggregate and thermal-treated materials that could substitute for Portland cement. First, the thermally treated materials were obtained by calcinating old Portland cement (OC-tt) and concrete demolition waste (CC-tt) at 550 °C, for 3 h. Second, plastic mortars with a perlite: cement volume ratio of 3:1 were prepared and tested for water absorption, mechanical strength, and thermal conductivity. The microstructure was also analyzed. Portland cement (R) was partially substituted with 10%, 30%, and 50% OC-tt. Thermal-treated materials negatively influenced the compressive and flexural strengths at 7 and 28 days. With an increase in the substitution percentage to 50%, the decrease in the compressive strength was 40% for OC-tt and 62.5% for CC-tt. The presence of 10% OC-tt/CC-tt positively influenced the water absorption. The thermal conductivity of the tested mortars was in the range of 0.37-0.48 W/m·K. SEM analysis shows the expanded perlite pores remained unbroken.

Masonry walls from reclaimed concrete demolition waste

The construction sector is the largest consumer of non-renewable resources and the most significant contributor to CO2 emissions. Reusing entire components or reclaiming their constituent parts, instead of recycling structural elements at the material level, is preserving the embodied energy of the structural elements. This contributes to energy conservation and addresses the mounting issue of construction waste in landfills. In order to develop a new avenue for reusing concrete, this study uses concrete demolition waste to construct masonry wallets, employing a construction technique reminiscent of traditional stone masonry with mortar. Importantly, this methodology is not confined to buildings initially designed for reuse, making it applicable to any reinforced concrete structure earmarked for demolition. Mechanical tests were conducted on the masonry wallets, including simple and diagonal compression tests. The results indicate that the strengths achieved are comparable to those of clay hollow brick masonry, opening up diverse applications, especially in the construction of residential buildings. Numerical analysis started with digital twinning of small-scale masonry wallets as a first step to future micro-modelling, FEM simulation, and calibration to best conform with the experimental test results. Through a comprehensive analysis encompassing embodied carbon footprint, mechanical properties, and economic considerations at the load-bearing wall level, this study highlights this reuse approach’s key advantages and drawbacks, providing insights into its feasibility within the framework of modern construction practices.

Pervious Concrete Made with Recycled Coarse Aggregate and Reinforced with Date Palm Leaves Fibers

This study considers 12 pervious concrete mixes incorporating 100% recycled coarse aggregate from old concrete demolition waste and containing various amounts of natural fine aggregate and date palm leaves fibers. First, the properties of the recycled aggregate in terms of their particle size distribution, abrasion resistance, crushing values, specific gravity and water absorption are obtained. Next, the pervious concrete density, compressive strength, tensile strength, permeability and porosity are determined by experimental testing following the relevant standards. The results are analyzed and compared to determine the influence of using recycled coarse aggregate in the mixtures and the impact of the amount of natural sand and volume fraction of the fibers on the mechanical properties, permeability and porosity of the concrete. Findings of the study showed that the use of recycled coarse aggregate in pervious concrete without fine aggregate reduced the compressive strength by 36% and tensile strength by 57%. Replacing 11.7% of the recycled coarse aggregate with natural sand and adding date palm leaves fibers in an amount equivalent to 0.64% volumetric content to such concrete helped increase the compressive strength by 16.2% and tensile strength by 3.2% above the corresponding strengths of the control mix. There is a clear relationship between permeability and porosity due to their correlation with the density of pervious concrete, and the effect of porosity on tensile strength is more influential than it is on the compressive strength. An equation that can predict the tensile strength of pervious concrete from the compressive strength is proposed, as a function of the natural fine aggregate fraction of the coarse aggregate and volumetric content of natural fibers. Results of the research confirm the feasibility of using recycled aggregate in pervious concrete mixes and the positive impact of natural fibers on the mechanical properties.

Viability of using limestone concrete waste from CDW to produce ternary cements type LC3

This paper analyzes manufacture of a new eco-cement (reduced CO2 footprint and LC3 clinker content) by replacing natural limestone with fine limestone concrete demolition waste (CDWH). The ternary cement’s content was partially replaced by a binary pozzolanic admixture (10%, 20%, and 30% proportions; 1:1 by weight) composed of CDWH and commercial metakaolin (MK). Results show the ternary eco-cement meets current standards’ chemical and physical requirements. The pozzolanic synergy of the additives —CDWH and MK— is comparable to silica fume, as reflected in the new mortars’ intrinsic properties (capillary water absorption and electrical resistivity), microporosity, and physical and mechanical characteristics, achieving maximum performance at 20% replacement. Kinetically, in ternary eco-cements, the formation of monocarboaluminate and hemicarboaluminate phases, the non-conversion of ettringite to monosulfoaluminate, and the reduction of the Ca/Si ratio in CSH gels all benefit kinetically as the replacement content increases. Use of limestone concrete demolition waste in manufacture of LC3 eco-cements is a viable option.

The Structural Behavior of Reinforced Concrete Beams Made with Locally Produced Recycled Aggregate in the UAE

In this study, the feasibility of utilizing locally produced coarse recycled aggregate (RA) from demolition waste in the UAE for structural applications was investigated. A comprehensive literature review on the subject showed that the shear and flexural responses of reinforced beams utilizing aggregate from concrete demolition waste are greatly dependent on the aggregate replacement ratio and the quality of the recycled aggregate. The experimental program in this study consisted of three phases. Phase I focused on the evaluation of the physical and mechanical characteristics of the RA, Phase II addressed the mix design and fresh and hard properties of the concrete, and Phase III dealt with the flexural and shear behavior of structural members. The research involved twelve 150 mm × 300 mm reinforced concrete beams with a length of 1500 mm or 2000 mm that were made with 0% (control), 50%, or 100% recycled coarse aggregate, replacing natural coarse aggregate (NA). Two target concrete compressive strengths, 25 and 35 MPa, were considered in the investigation. The results showed that the recycled aggregates had lower crushing and LA abrasion values by 40% and 18–28%, respectively, whereas the absorption capacity was 40–300% higher compared to the natural aggregate. In addition, the mechanical properties of the concrete made with different replacement ratios (R%) of RA were either similar or slightly less than those of the control mix. The shear beam tests with fc′ = 25 MPa showed that the 50%- and 100%-replacement-ratio beams demonstrated closely matched normalized shear strength values that exceeded their corresponding NA beam by 12.5%, while the shear beam tests with fc′ = 35 MPa showed that the NA beam exhibited normalized shear strength surpassing the 50% RA and 100% RA beams by 12.5% and 17.5%, respectively. In the flexural beam tests, the flexural strength exhibited minimal disparities for the beams that shared the same RA% but differed in their compressive strength targets, and overall, the variation in the RA% had a marginal impact on the flexural strength of the beams. Further, an increase in the RA% corresponded to an increase in the shear ductility index, which was in contrast with the findings on the flexural ductility index. Furthermore, predictions of flexural strength using the ACI318-19 code and shear strength using the strut-and-tie model yielded comparable results to the experimental ones.

Comparative Study of Concrete Using Recycled Fine Aggregate

Abstract: Waste handling and management is the major problem faced by countries in the modern era. Concrete demolition waste has been one of the sources of creating environmental pollution. There have been many strength and durability studies taking place to analyze the concrete made with fine aggregate which has been recycled from old concrete structures and proved high strength compared to the concrete made with new materials. Those research works are limited in analyzing finer divisions of the concrete made with the aggregates which have been recycled. This paper concentrates on the applications of recycled Fine Aggregate (RFA) as a partial replacement instead of the fine aggregates available naturally to prepare the concrete. With a view to the above needs, the present study is aimed to determine the strength properties of RFA concrete depending on the various content of RFA and to compare them to the strength properties of concrete made with natural fine aggregates (NFA). Fine aggregates of high FM of 2.6 were used for recycled and natural concrete. After performing the compressive strength test with partial replacements of 30%, 40%, 50%,60%,70% and 80%of RFA with NFA, it was found that concrete made with the following replacements RFA has less strength than concrete made with NFA but with not much difference. So, RFA can be used as a replacement for NFA in concrete production. In addition, partial replacement of RFA can be used in structures of less importance such as temporary walls, the base of roads, light traffic roads, pavements in college campuses etc.

Recycled Concrete Aggregated for the use in Roller Compacted Concrete: A Literature Review

The using of recycled aggregates from construction and demolition waste (CDW) can preserve natural aggregate resources, reduce the demand for landfill, and contribute to a sustainable built environment. Concrete demolition waste has been proven to be an excellent source of aggregates for new concrete production. At a technical, economic, and environmental level, roller compacted concrete (RCC) applications benefit various civil construction projects. Roller Compacted Concrete (RCC) is a homogenous mixture that is best described as a zero-slump concrete placed with compacting equipment, uses in storage areas, dams, and most often as a basis for rigid pavements. The mix must be sufficiently dry to support the weight of vibratory machinery while still being sufficiently moist to enough paste binder dispersion throughout the mass for efficient compaction. Limited studies into the use of RCC with fine recycled aggregate not from pavements are figured. This study aims to see how well-recycled concrete aggregates (RCA) perform in RCC mixtures. Also how well waste concrete could be used as a fine and coarse aggregate substitute in roller-compacted concrete pavement mixes, to create a good concrete mix in both wet and firm phases. The test results of mechanical properties showed 10% RCA is similar to those in the reference mix in the compressive strength, a 100% RCA ratio reduces compressive strength by almost 30%. Comparing Reference mix and Recycled concrete by 30% replacement, the compressive strength drops by just 6% when the RCA ratio is 30%.

Processing of laboratory concrete demolition waste using ball mill

The demand for natural aggregates in the twenty-first century is at an all-time high due to rapid urbanisation and infrastructure development. Finding alternative aggregate materials is a challenge for achieving construction sustainability. Both the depletion of natural resources and the improper disposal of construction and demolition (C&D) waste can be ameliorated by the widespread use of recycled aggregates in construction. Due to the attached mortar, aggregates from C&D waste must be processed before using them in concrete. Various combinations of ball mill processing parameters were used to produce relatively higher-quality aggregates. Water absorption was used as the primary criterion for determining the quality of processed aggregates. The water absorption capacity of recycled coarse aggregate was found to be decreased from 5.8% to 1.5% as a result of effectively removing the attached mortar by employing ball mill processing. Specific gravity, impact, and crushing values are also improved after processing, as discussed and illustrated in this paper.

Elaboration of a Self-Compacting mortar based on concrete demolition waste incorporating blast furnace slag

The high consumption of natural sand in the manufacture of mortar and concrete has inevitably led to serious ecological impacts. On the other hand, the steel industry is always accompanied by the production of unused by-products such as granulated blast furnace slag. This research aims to use a fine fraction of construction and demolition (C&D) waste as a substitute for natural sand and, ground granulated blast furnace slag (GGBFS) as a substitute for cement for the manufacture of self-compacting mortars. 15 mortars are formulated where 0, 25, 50, 75 and 100% natural sand (NS) are replaced by recycled concrete sand (RCS) and 0, 20 and 40% ordinary cement are replaced by GGBFS. The obtained results show that it is possible to manufacture self-compacting mortars with RCS, with an optimum of 50%. The use of this type of sand affects negatively the porosity and capillarity water absorption of mortars; this can be compensated by the use of GGBFS as a cement substitute. A 20% slag substitution rate can also improve the long-term compressive strength.

Durability, life cycle cost and life cycle assessment of binary mixtures with fly ash, rice husk ash and concrete demolition waste

Abstract This study analyses, by means of lifespan cost and lifespan assessment, the production of binary concrete admixtures compound by artificial pozzolan and concrete demolition waste. Ten formulations were developed, differentiating them in terms of mixtures, binder and aggregate content, in order to verify their potential use in concrete columns. The replacements were 25% of Portland cement for fly ash and rice husk ash, 15% and 30% of natural coarse aggregates for concrete demolition waste. The results revealed that the mixtures with pozzolan and demolition waste showed higher resistance to chloride penetration. The lowest concrete cost was achieved in the highest compressive strength (35 MPa) and the concrete admixture containing 15% replacement of the natural coarse aggregate by the recycled concrete aggregate and 25% substitution of cement by rice husk ash can be classified as the most environmentally sustainable one, especially in carbon dioxide emissions, among the mixtures studied.

Recycling of Concrete Demolition Waste Powder as a Sustainable Material in Portland Cement Pastes Modified with Nano-silica

In recent years, researchers dedicated themselves to explore the possibility of introducingconcrete waste powder (CWP) into Portland cement as a sustainable material for Portland cement to reduce as possible the environmental pollution with this concrete demolition wastes. To optimize the effect of CWP on cement-based materials, this paper usesnano-silica (NS) to improve the hydration and mechanical properties of cement-based materials with CWP. Results indicated that after adding NS into CWP cement pastes, the setting time of cement pastes was significantly reduced, while the early rate of hydration and hydration heat increased. Besides, the mechanical strengths of the cement pastes increased as CWP replaced at the expense of the cement only up till 15 weights %, and then decreased. The addition of nanosilica (NS) can compensate the mechanical strength loss caused by CWP as supplementary cementing materials. The higher ratios of CWP than 15 weight % increased the pore volume or porosity. In contrast, NS in CWP blended cement significantly decreased the porosity, and increased the proportion of harmless pores. Hence, NS reduced the porosity, which in turn improved and enhanced the bulk density and mechanical properties. The optimum amount of NS is 2.5 weight % which resulted in the best results. The heat of hydration of the different cement batches in the two groups adversely affected with the incorporation of CWP, but little improved with NS. The obtained results were confirmed by the ultrasonic pulse velocity (USPV) test, where the cement batch PP15 (Group I) and PS2.5 (Group II) achieved the highest conformance.

Ecotoxicological implications of leachates from concrete demolition debris on oligochaetes: survival and oxidative stress status

Urbanization and population growth demand the construction of structures to facilitate the need for space, and old infrastructures must make space for new ones leading to demolition and concrete debris. In addition to demolition, aging and weather are factors leading to concrete deterioration and, thus, a new challenge as an environmental pollutant. Studies on how concrete debris and leachate affect biota in the environment are limited. The present study aimed to understand the effects of leachate from various sizes of concrete debris on the three oligochaete species Enchytraeus crypticus, Tubifex, and Lumbriculus variegatus. Acute toxicity testing was carried out to determine the adverse effects over time. The oligochaetes’ survival was monitored as well as the activity of the biotransformation enzyme glutathione S-transferase and the antioxidative enzyme catalase as indicators of the oxidative stress status. Leachate from the smallest concrete particle size (<1 mm) was found to be the most toxic as it caused, on average, 6-fold increased oligochaete mortality compared to the larger pieces (2–5 cm) after 96 h of exposure, potentially due to the larger surface area facilitating the release of toxicants. Substrate buffered the toxic effect of the leachate with 42 ± 12% fewer mortalities and reduced adverse effects on the enzymes. Of the three oligochaetes, E. crypticus was the most resilient to the concrete leachate. The study is the first to investigate the effects of concrete leachate on oligochaetes.

Experimental Study of Concrete Making Using Recycled Coarse Aggregate

Concrete is a form of construction in the form of a composite material consisting of a mixture of fine aggregate, coarse aggregate, cement, and water. However, in certain cases, the concrete application is often a problem, especially the lack of a minimal amount of coarse aggregate material, increasing material prices. Recycled concrete aggregate (RCA) is an embodiment of concrete composed of recycled materials. Recycled material is obtained from fragments or remnants of the demolition of unused concrete. The method used to make concrete from the constituent materials using concrete waste as coarse aggregate per the rules of science is experimental. The tests are the aggregate moisture content test, the mud content test, the coarse aggregate abrasion test, the slump test, and the concrete compressive strength test at 28 days of treatment. The compressive strength results showed that the normal concrete sample could reach FC 18.53 MPa. The concrete sample using recycled coarse aggregate reached FC 23.79 MPa, so using recycled materials for manufacturing concrete can achieve the planned target

Performance of Concrete made with Natural Aggregate and Multi-cycle Recycled Concrete Aggregate

The research concentrated on the use of concrete demolition waste (CDW) to achieve long sustainability, as coarse aggregate in the production of Recycled aggregate concrete (RAC). Concrete demolition waste (RCA) is used to replace natural coarse aggregates (NCA) in M-25 grade concrete production, preserving natural resources and reducing the amount of demolition waste that must be landfilled. The effect of substituting 25%, 50%, and 100% NCA with three cycles of RCA on the mechanical characteristics with an endurance of hardened concrete was studied and compared to control concrete. The results of this study show that it is possible to use the RCA coming from CDW in order to the production of concrete. The performance of concretes with 0% and 25% replacement of NCA by RCA was nearly identical to that of concrete without replacement, but the strength of concrete was reduced with 50% and 75% replacement.

Experimental Investigation of Recycled Fine Aggregate from Demolition Waste in Concrete

In this study, locally produced recycled fine aggregate from concrete demolition waste was investigated for potential replacement of sand in new concrete mixes. Tests for the waste material included visual examination, chemical composition, grain size distribution, specific gravity, and fineness modulus. Tests on the incorporated recycled fine aggregate in new concrete mixes involved tests of the hardened plain concrete product. In total, eight concrete mixes were considered, of which four had low cement content with 30 MPa target strength, and the other four had high cement content with 55 MPa target strength. For each cement content, the four concrete mixes incorporated fine aggregate replacement ratios of 0% (control), 25%, 50%, and 100%. The hardened concrete tests involved cubes, cylinders, and prisms. The tests addressed compressive strength, tensile strength, and modulus of rupture in accordance with the relevant ASTM standards. In all cases, the average of two tested samples at the age of 28 days was considered. Results of the study showed that the recycled fine aggregate has some cementitious properties, which is capable of hardening when mixed with water and left to dry, even without adding cement from exterior sources. All tested concrete specimens made with recycled fine aggregate exhibited compressive and tensile strengths at least equal to 75% that of the control specimens that contained natural fine aggregate. However, for concrete mixes utilizing low cement content that can yield a compressive strength around 30 MPa with natural aggregate, replacement of 25% or 100% of the natural fine aggregate by weight with locally produced recycled fine aggregate from crushed old concrete can match and often exceeds the compressive and tensile strength of concrete made with virgin aggregate.

Eco-friendly cementless concrete from hazardous iron ore tailing and waste of cellulose-pulp, concrete demolition, and lime production

Eco-friendly cementless concrete from hazardous iron ore tailing and waste of cellulose-pulp, concrete demolition, and lime production

Modeling carbonation depth of recycled aggregate concrete using novel automatic regression technique

Waste from concrete demolition is a sustainability concern that can be mitigated when used as recycled aggregate in concrete instead of virgin natural aggregates. However, the durability of recycled aggregate concrete (RAC), including concrete carbonation, needs to be investigated before the widespread applications of RAs in construction. Developing artificial intelligence-based predictive models for estimating the carbonation depth of RAC using the available data can reduce the need for experimental studies to generate reliable models for the service life assessment of concrete structures. In this study, artificial bee colony expression programming (ABCEP), as a novel branch of automatic regression technique, was used to predict the carbonation depth of RAC from a large dataset consisting of 655 data samples. Several ABCEP architectures were developed, different analyses were conducted, and a comparison study between the best ABCEP model and previous models published in the literature was conducted. The findings show that the best structure of the ABCEP model could estimate the carbonation depth of RAC with a reasonable root mean square error of 3.33 mm. The exposure time was the most influential parameter affecting the carbonation depth of RAC. Furthermore, the ABCEP model could outperform the previous models, despite the larger unknown dataset used to test its performance.

The effect of the use of recycled coarse aggregate on the performance of self-compacting concrete (SCC) and its application

The demand for self-compacting concrete is very high because this concrete has high flowability and has resistance to segregation. Natural aggregates are of high value, while concrete demolition materials are abundant and of low value. So that the recycled coarse aggregate can be used as concrete material, this study analyzes the characteristics of Self Compacting Concrete (SCC) using recycled coarse aggregate from construction waste. Tests for aggregate wear, aggregate hardness, compressive strength of concrete and tensile strength of concrete were carried out. The wear test refers to the standard AASHTO T-96-74, ASTM C-131-55 and SNI 2417-2008. This test uses recycled coarse aggregate that has been washed so that the sludge content is clean; after that, it was baked with the used aggregate, the aggregate that passed the 12.5 mm sieve and was retained in the 9.5 mm sieve. The test object is pressurized 40 tons at a speed of 4 tons/minute. Concrete Compressive Strength Test refers to SNI 03-1974-2011, using a scale with an accuracy of 0.3 % of the weight of the concrete, a concrete press machine and a capping machine. While the split tensile strength test of concrete refers to SNI 03-2491-2014, carried out on days 7, 21 and 28 with a cylindrical test object. Variations of recycled aggregates start from 0 %, 25 %, 50 %, 75 %, and 100 %. The design's compressive strength is 25 MPa. The results showed that the recycled aggregates had good gradation, high absorption and low specific gravity compared to natural aggregates. The recycled coarse aggregate reduces the compressive strength of the concrete and causes a decrease in a slump, thereby reducing the split tensile strength of the concrete

Global warming potential of recycled aggregate concrete with supplementary cementitious materials

Significant materials research has focused on the reduction of concrete demolition waste via reuse in recycled aggregate concrete (RAC) and the reduction in cement emissions through the use of blended binders incorporating supplementary cementitious materials (SCMs). This work is largely predicated on the assumption that the environmental impact of concrete will be reduced as a result of the inclusion of waste materials. That is, research focusing on the development of RAC mix designs has largely been conducted without parallel life-cycle assessment (LCA) to quantify the true environmental impact. Here, a LCA is conducted to quantify the global warming potential (GWP) of 590 mix designs derived from 42 studies that incorporate both recycled aggregate and a range of SCM types. The assessment considers both a volumetric functional unit and a combined volumetric and strength functional unit, the analysis also considers the absorption of atmospheric carbon via concrete carbonation both during and after service. For each type of SCM the range of predicted GWP is defined, and it is shown that substantial reductions in CO2 equivalent emissions arise from SCM addition. Further, the use of recycled aggregate is shown to be most environmentally beneficial in lower strength concretes in which it is possible to achieve the same mechanical properties as natural aggregate concrete controls.