A survey of the mechanical properties of concrete for structural purposes prepared on construction sites

Abstract

This paper aims to study the concrete dosage conditions for structural purposes in construction sitesl, and the impacts of non-compliance of structural concrete for structural safety, having as study case the city of Angicos / RN. Were analyzed the dynamic elasticity modulus, static elasticity modulus and the compressive strength of concrete samples. Was conducted to collect the survey data, a field research aiming to gather information about dosage of concrete used in the works, as well as the collection of cylindrical specimens of 150 mm diameter by 300 mm of height, prepared according to practice of those professionals. The study indicated a clear necessity to reflection on the subject, since there is no concern, or even, a lack of knowledge by the interviewed professionals regarding the care and procedures necessary for the production of concrete with satisfactory quality, once at least 50% of evaluated construction sites presented compressive strength lower than 20 MPa, minimal strength to structural concrete, as recommended by ABNT-NBR 6118:2014.

Assessment of Compressive Strength Variations of Concrete Poured in-Site of Residential Buildings in Isoko District, Delta State, Nigeria

“…It was observed in the result (Table 3) that the buildings that satisfactorily met the compressive strength requirement, were those that the managers utilized lower water- cement ratios and fairly conventional concrete mix ratios. This confirmed a previous report by Ribeiro et al (2016) which stated that water-cement ratios considerably affect the compressive strength of in-situ concretes. The poor quality concrete produced in building 8, despite its better mix ratio, could be attributed to the volume of water and the production method used during the concrete production.…”

“…Some parts of building structures that are largely utilize concrete include: foundation footings, floors, basement walls, columns, beams, slabs, etc. The quantity of fine and coarse aggregates, the volume and cement grade, the production process, the curing methods, the water-cement ratio and the admixtures added, amongst other factors, significantly affect the physic-mechanical properties of the concrete (Okumu et al, 2016;Ribeiro et al, 2016;Akpokodje et al, 2021). Although concrete strength is dependent on the water volume present in the fresh concrete, excessive water affects the quality of concrete gel produced (C-S-H) and predisposes the concrete so produced to failures (mostly in the form of shrinkage and cracking).…”

“…Several researchers (Namyong et al, 2004;Okazaki et al, 2012;Ribeiro et al, 2016) had studied the compressive strength of in-situ concrete used for various building constructions across the world. However, current literature search revealed little information on the compressive strength of concrete used for residential building construction in Delta State, Nigeria.…”

Estudo Do Comportamento Eletroquímico Do Concreto Auto Adensável E Do Concreto Convencional Submetidos a Ciclos De Secagem E Molhagem Exposto Ao Ataque De Cloretos

“…O vasto uso do concreto como material de construção civil imputa ao meio técnico a preocupação crescente em relação às condições de qualidade do material e aos requisitos de desempenho e segurança estrutural (RIBEIRO et al, 2016). Projetar uma infraestrutura otimizada com melhorias do uso dos recursos, escolha de materiais e processos construtivos atendendo as normas e especificações se torna cada vez mais importante onde desastres anteriores mostram que as falhas na infraestrutura geralmente excede significativamente os danos físicos a esses sistemas (GARDONI E MURPHY, 2018).…”

Determination of Elastic and Dissipative Properties of Concrete Under Dynamic Deformation

“…Для идентификации физико-механических свойств материала могут быть использованы эксперименты по измерению скорости распространения упругих волн либо по регистрации затухающих свободных колебаний [25][26][27][28][29][30][31][32]. Одним из основных недостатков этих подходов является идеализация динамического вибрационного (или волнового) деформационного процесса при математической интерпретации экспериментальных измерений.…”