Effect Of Superplasticizer Dosage Research Articles

Effect of Superplasticizer Dosage on Compressive Strength and Microstructure of High Volume Basic-Oxygen Slag Mortar Exposed to Sea Water Attacks

The influence of superplasticizer addition on durability reinforcement of cement mortars made with basic-oxygen blast-furnace slag fine aggregate (BOF) as completely substitute for natural sand after being exposed to sea water solution for 6 months was evaluated by determining physico-mechanical characteristics in terms of water absorption and compressive strength in addition to microstructure analysis. In this procedure, all studied mixtures were doped with 1% and 2% superplasticizer. After the initial curing of samples in tap water for 28 days, they were subjected to sea water solution for 6 months using water to binder ratios of 0.35 and 0.45. The new hydration phases and microstructure of hardened specimens were identified by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The results showed that cement mortars with slag fine aggregate blended with 2% SP offered better water absorption, compressive strength and microstructure than their counterparts with natural sand against sea water attacks. Therefore, they can be used in offshore structure applications.

The effect of superplasticizer dosage on fresh properties of self- compacting lightweight concrete produced with coarse pumice aggregate

The use of superplasticizer in the manufacture of self-compacting concrete is graduallymore common. Each type of superplasticizer available in the market has differentcompositions, causing differences in dosage requirement. Also, superplasticizer affectthe fresh and hardened properties of concrete. In this experimental study the effect ofdifferent dosage of superplasticizer (SP) on fresh properties of self-compactinglightweight concrete (SCLC) containing coarse aggregate pumice were studied by usingfive different percentages for (SP) (1%, 1.3%, 1.5%, 1.7% and 2%) of the binderweight. (SCLCs) were produced with constant binder content of 550 kg/m 3 and at awater-to-binder ratio of 0.26. 20% of portland cement was replaced with fly ash byweight. The workability of SCLCs was quantitatively evaluated by slump flow time anddiameter, V-funnel flow time, and L-box height ratio. Moreover, compressive strengthof hardened SCLCs was measured at 28 days by using compression machine andRebound hammer test. The results show that with the increase of (SP) dosage in theconcrete mixture, the flowability increased. However, there is an optimum value of (SP).The increase of (SP) dosage is accompanied by decreasing of T 500 slump flow and V-funnel time until it reaches the optimum level. Nevertheless, excessive use of (SP) leadto increase of slump flow diameter.

Effect of Superplasticizer Dosage on Workability and Strength Characteristics of Concrete

The use of chemical admixtures in concrete is a common solution to achieve full compaction particularly where reinforcement congestion and shortage of skilled workers. The past researchers have been underscored the use of chemical admixtures imparts the desirable properties to concrete in both fresh and hardened state. This paper has been made an attempt to study the influence of superplasticizer dose of 400ml, 600ml, 800ml, 1000ml and 1200ml/100 kg of cement on performance of Concrete. The experimental tests for fresh and hardened properties of concrete for three mixes of 30 MPa grade are studied and the results are compared with normal concrete. The tests considered for study are, slump test, slump loss, flow table and compressive strength test The results show that for the constant water cement ratio, increase of superplasticizer dose in properties of concrete leads to gain of good workability. Moreover, there is also increase in compressive strength than that of normal concrete mix.

Rheology and Setting Time of Cement Paste

Experimental results about effect of superplasticizer dosage, fly ash content and water to cement ratio on rheology and setting time are presented. 16 samples are evaluated using a Brookfield laboratory rheometer and a standard vicat needle apparatus. Spread of the samples is also measured using mini slump cone (d1=60mm, d2=35, h=60mm) and an empirical relationship between spread and yield stress is put forward.

Effect of Superplasticizer Dosage on Mechanical Properties, Permeability, and Freeze-Thaw Durability of High-Strength Concretes With and Without Silica Fume

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